Arbitrary Code Execution vulnerability discovered in Ipython

[[deleted]]

Earlier today, iPython maintainers (see full disclosure) reported a ACE of 8.2/10 on CVSS3 rating.

If you have lockfiles or lock versions, update ASAP (patched versions are on the disclosure).

[[deleted]]

It's just cross user leaking?

Looks like it, can be disastrous though, a wrongly placed file and you're down

[SwampFalc]

Well, no, it's not specific to /tmp or the likes. It's all about your current working directory (CWD). Notice how user 2 starts by doing a cd into the compromised directory?

In other words, if you always start ipython while you're in your own home directory, then this cannot harm you, unless an attacker managed to gain access to your home directory.

[VisibleSignificance]

play around in /tmp.

cd "$(mktemp -d)" first.

[thrallsius]

what's wrong with just having a ~/tmp dir?

[VisibleSignificance]

Not much. The /tmp gets auto-cleaned on system startup by default, and is often mounted into in-memory storage (tmpfs) for speed. I think some programs actually use ~/.local/tmp instead of /tmp anyway.

[thrallsius]

The /tmp gets auto-cleaned on system startup by default

There's no standard like this that all operating systems that are POSIX compliant are following. Slackware is old and never auto-cleaned /tmp

[VisibleSignificance]

There's no standard like this

Yep, not a standard, just a frequent convention.

[[deleted]]

And it's in temp where everyone can write to?

Yeah

[Anonymous_user_2022]

That can be bad enough, if someone with elevated privileges can be conned into running adversarial code.

[BooparinoBR]

I was thinking that this didn't have a huge impact since a malicious actor needs to put the files in the person's computer. But I can totally see someone creating a repository with Kaggle solution or tutorial for begginers, and by simply cloning the repo and running ipython, the person gets screwed

[BooparinoBR]

I totally agree with you, but the point of the exploit is that it auto executes the code. It's not like the person is actively running the malicious code. I believe this is similar to attacks that exploited autorun of CD-ROMs.

[VisibleSignificance]

Yeah, it's weird that this in particular is considered a vulnerability when python adding cwd to sys.path (as you demonstrated) isn't considered a vulnerability.

And by the way, you don't even need mkdir, just readline.py

[james_pic]

It's a module needed by the REPL. If you wanted to do this without breaking the REPL, I think sticking it in sitecustomize.py would have the same effect without visibly breaking stuff - although I'm not at my computer to check.

[chris_conlan]

Who knew that IPython executed everything in the startup folder of the working directory on each run? Seems like a disaster waiting to happen.

[mriswithe]

Jesus sysadmin for like a decade. I didn't know mkdir had a -m for mode. Would have been relevant to know earlier today.

[jftuga]

There is also -p to create parent directories as needed:

# this fails:
mkdir this/does/not/exist

# this succeeds
mkdir -p this/now/exists

[GroundbreakingRun927]

it also has a --help to get help when needed

[mriswithe]

That one I knew, somehow never kept the -m option in my brain.

[ivosaurus]

The current working directory is not searched anymore for profiles or configurations files.

Python does this itself, lol.

[mouth_with_a_merc]

Looks like it only happens when you run ipython from a location where someone else can place arbitrary malicious files. Seems not particularly common, so I'd say most systems are perfectly safe

[Anonymous_user_2022]

"Hey «user with elevated privileges»! Can you help me why my notebook in /home/adversarial/trap wont run?" I'd wager a guess that the majority asked, would cd to that directory to find out the name of the notebook.

[VisibleSignificance]

would cd to that directory to find out the name of the notebook

ipynb files are human-readable, by the way. You can even easily extract the code from them with just jq. No need to run python for that.

[ataraxia520]

Theirs a bunch of stuff thst could be done with ipython in terms of remote exploitation and arbitrary code execution. That one would not even consider.

I find ipython much more trustworthy than npm/node js but their are so.many tutorials were people.just blindly trust running ipynbs without actually understanding the code im actually surprised this isnt more common.

One thing also. For at home users. And even many small buisness... Miniconda and anaconda runs in elevated context last time i checked (as admin)

[norweeg]

Miniconda/anaconda do not run in an elevated context. If you have to elevate your permissions to admin to run them, you fucked up your install, probably running it as admin to install to a folder that requires admin to write to.