Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting adm-zip package, versions <0.4.11

Overview

adm-zip is a JavaScript implementation for zip data compression for NodeJS.

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

Details

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

Remediation

Upgrade adm-zip to version 0.4.11 or higher.

References

• GitHub Commit

• GitHub Commit

• Hackerone Report

• Zip Slip Advisory

• Zip Slip Advisory