Even "cat readme.txt" is not safe

aarkadiyt about 5 hours ago 25 commentsRead Article on blog.calif.io

⚡ Community Insights

Discussion Sentiment

22% Positive

Analyzed from 840 words in the discussion.

Discussion (25 Comments)Read Original on HackerNews

Drunk_Engineer•25 minutes ago

An almost identical security issue in iterm2 reported 6 years ago:

https://blog.mozilla.org/security/2019/10/09/iterm2-critical...

valleyer•2 minutes ago

Wait, so... cat -v not considered harmful, then?

KerrickStaley•about 3 hours ago

> At the time of writing, the fix has not yet reached stable releases.

Why was this disclosed before the hole was patched in the stable release?

It's only been 18 days since the bug was reported to upstream, which is much shorter than typical vulnerability disclosure deadlines. The upstream commit (https://github.com/gnachman/iTerm2/commit/a9e745993c2e2cbb30...) has way less information than this blog post, so I think releasing this blog post now materially increases the chance that this will be exploited in the wild.

Update: The author was able to develop an exploit by prompting an LLM with just the upstream commit, but I still think this blog post raises the visibility of the vulnerability.

ezoe•about 2 hours ago

I guess traditional moratorium period for vulnerability publication is going to be fade away as we rely on AI to find it.

If publicly accessible AI model with very cheap fee can find it, it's very natural to assume the attackers had found it already by the same method.

saddist0•about 1 hour ago

It’s a wrong way to look at things. Just because CIA can know your location (if they want to), would you share live location to everyone on the internet?

LLM is a tool, but people still need to know — what where how.

lxgr•42 minutes ago

Not sure if that's a great example. If there's a catastrophic vulnerability in a widely used tool, I'd sure like to know about it even if the patch is taking some time!

The problem with this is that the credible information "there's a bug in widely used tool x" will soon (if not already) be enough to trigger massive token expenditure of various others that will then also discover the bug, so this will often effectively amount to disclosure.

I guess the only winning move is to also start using AI to rapidly fix the bugs and have fast release cycles... Which of course has a host of other problems.

chromacity•about 1 hour ago

This is cool work, but it's also somewhat unsurprising: this is a recurring problem with fancy, richly-featured terminal apps. I think we had at least ten publicly reported vulns of this type in the past 15 years. We also had vulnerabilities in tools such as less, in text editors such as vim, etc. And notably, many of these are logic bugs - i.e., they are not alleviated by a rewrite to Rust.

I don't know what to do with this. I think there's this problematic tension between the expectation that on one hand, basic OS-level tools should remain simple and predictable; but on the other hand, that of course we want to have pretty colors, animations, and endless customization in the terminal.

And of course, we're now adding AI agents into the mix, so that evil text file might just need to say "disregard previous instructions and...".

SrslyJosh•7 minutes ago

> We'd like to acknowledge OpenAI for partnering with us on this project

Thanks, saved me some reading time.

Bender•about 4 hours ago

What happens if instead of 'cat readme.txt' one does 'strings -a --unicode=hex readme.txt'? Does iTerm still monkey with it?

    alias cat
    cat='strings -a --unicode=hex'

halJordan•about 3 hours ago

The whole "cat can hide unprintable characters" is such an old demo. I get this is a novel spin on which unprintable characters were doing but yeah, this was also my thought

Bender•about 3 hours ago

I'm just used to aliasing cat to strings after working around a lot of red-team penetration testers. They would prank each other and me all the time. Had to also watch out for this one [1].

[1] - https://thejh.net/misc/website-terminal-copy-paste

jdshaffer•about 1 hour ago

Is it a problem with "cat" or a terminal problem?

If I wrote my own version of cat in C, simply reading and displaying a single TXT character at a time, wouldn't I see the same behavior?

rezonant•about 1 hour ago

As the article shows, it is a bug in iTerm2. cat is just one program that could trigger it, the key thing is outputting attacker controlled text to the terminal when the attacker can control what files are present (ie unzipping a folder that includes a specific executable file at a well chosen location that gets triggered to run when the readme is output to the terminal)

readthenotes1•about 1 hour ago

Give this one MS-DOS shell headline would be " why I never am using Microsoft again" or something dramatic like that.

It is a problem in iterm, Apple's overlay, not in the cat program. Program. At least from Reading the article. That's what I got

rezonant•36 minutes ago

It's actually a third party terminal emulator: https://iterm2.com/

CodesInChaos•about 2 hours ago

I never understood why outputting unescaped data is viewed differently from generating unenclosed html.

Like why doesn't `println` in a modern language like rust auto-escape output to a terminal, and require a special `TerminalStr` to output a raw string.

im3w1l•about 2 hours ago

I think the problem is that 1) You want to be able to write arbitrary bytes, including shell escape sequences into files. 2) You don't want to accidentally write terminal escape sequences to stdout. 3) Stdout is modeled as a file.

Consider cat. It's short for concatenate. It concatenates the files based to it as arguments and writes them to stdout, that may or may not be redirected to a file. If it didn't pass along terminal escapes, it would fail at its job of accurate concatenation.

Now I don't mean to dismiss your idea, I do think you are on the right track. The question is just how to do this cleanly given the very entrenched assumptions that lead us where we are.

lxgr•about 1 hour ago

> that may or may not be redirected to a file

This is usually knowable.

It's a different question whether cat should be doing that, though – it's an extremely low level tool. What's wrong with `less`? (Other than the fact that some Docker images seem to not include it, which is pretty annoying and raises the question as to whether `docker exec` should be filtering escape sequences...)

im3w1l•7 minutes ago

Sometimes you don't want to open stuff in a pager.

TZubiri•about 2 hours ago

More like iTerm2 is not safe

ButlerianJihad•about 2 hours ago

A long, long time ago, it was literally possible to stuff the command buffer of a “dumb terminal” using ESC sequences and spoof keyboard input. So yeah, don’t count on ’cat’ being safe if your terminal isn’t!

tasty_freeze•40 minutes ago

I did this in 1985 on SOROC terminals we had in my first job out of college. However, it depended on the dip switch settings that were under a little door on top of the keyboard.

anthk•16 minutes ago

It is under 9front. There are not terminals, you wan windows with shells on it.

einpoklum•about 1 hour ago

Even click-baity titles are not safe.

holoduke•about 2 hours ago

With LLM tool use potentially every cat action could be a prompt injection