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GHSA-wfm5-v35h-vwf4
No affected components available
Summary
When resolving a program, Python/Windows look for the current working directory, and after that the PATH environment (see big warning in https://docs.python.org/3/library/subprocess.html#popen-constructor). GitPython defaults to use the git command, if a user runs GitPython from a repo has a git.exe or git executable, that program will be run instead of the one in the user's PATH.
Details
This is more of a problem on how Python interacts with Windows systems, Linux and any other OS aren't affected by this. But probably people using GitPython usually run it from the CWD of a repo.
The execution of the git command happens in
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/cmd.py#L277
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/cmd.py#L983-L996
And there are other commands executed that should probably be aware of this problem.
PoC
On a Windows system, create a git.exe or git executable in any directory, and import or run GitPython from that directory
python -c "import git"
The git executable from the current directory will be run.
Impact
An attacker can trick a user to download a repository with a malicious git executable, if the user runs/imports GitPython from that directory, it allows the attacker to run any arbitrary commands.
Possible solutions
- Default to an absolute path for the git program on Windows, like
C:\\Program Files\\Git\\cmd\\git.EXE(default git path installation). - Require users to set the
GIT_PYTHON_GIT_EXECUTABLEenvironment variable on Windows systems. - Make this problem prominent in the documentation and advise users to never run GitPython from an untrusted repo, or set the
GIT_PYTHON_GIT_EXECUTABLEenv var to an absolute path. - Resolve the executable manually by only looking into the
PATHenvironment variable (suggested by @Byron)
[!NOTE] This vulnerability was reported via email, and it was decided to publish it here and make it public, so the community is aware of it, and a fix can be provided.
The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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