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GHSA-78m5-jpmf-ch7v
No affected components available
Summary
Unsafe extracting using shutil.unpack_archive() from a remotely retrieved tarball may lead to writing the extracted file to an unintended destination.
Details
Extracting files using shutil.unpack_archive() from a potentially malicious tarball without validating that the destination file path is within the intended destination directory can cause files outside the destination directory to be overwritten.
The vulnerable code snippet is between L153..158.
response = requests.get(url, stream=True)
with open(zippath, "wb") as f:
f.write(response.raw.read())
shutil.unpack_archive(zippath, unzippedpath)
It seems that a remotely retrieved tarball which could be with the extension .tar.gz happens to be unpacked using shutil.unpack_archive() with no destination verification/limitation of the extracted files.
PoC
The PoC provided showcases the risk of extracting the non-harmless text file sim4n6.txt to a parent location rather than the current folder.
> tar --list -f archive.tar
tar: Removing leading `../../../' from member names
../../../sim4n6.txt
> python3
Python 3.10.6 (main, Nov 2 2022, 18:53:38) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import shutil
>>> shutil.unpack_archive("archive.tar")
>>> exit()
> file ../../../sim4n6.txt
../../../sim4n6.txt: ASCII text
A Potential Attack Scenario
- An attacker may craft a malicious tarball with a filename path, such as
../../../../../../../../etc/passwd, and then serve the archive remotely, thus, providing a possibility to overwrite the system files.
Mitigation
Potential mitigation could be to:
- Use a safer module, like
zipfile. - Validate the location of the extracted files and discard those with malicious paths such as a relative path
..or absolute ones.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. 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 vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
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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