Arbitrary File Write via Archive Extraction (Zip Slip) Affecting github.com/mholt/archiver/cmd/arc package, versions >=3.0.0 <3.3.2

github.com/mholt/archiver/cmd/arc is a cross-platform, multi-format archive utility and Go library.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) via the Unarchive functions.

It is exploited using a specially crafted zip archive, that holds path traversal filenames. When exploited, a filename in a malicious archive is concatenated to the target extraction directory, which results in the final path ending up outside of the target folder. For instance, a zip may hold a file with a "../../file.exe" location and thus break out of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

+2018-04-15 22:04:29 ..... 19 19 good.txt

+2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys

• Fix Commit
• GitHub PR
• GitHub PR 2
• Zip Slip Advisory
• Zip Slip Advisory