Autolab is a course management service that enables auto-graded programming assignments. A Tar slip vulnerability was found in the MOSS cheat checker functionality of Autolab. To exploit this vulnerability an authenticated attacker with instructor permissions needs to upload a specially crafted Tar file. Both "Base File Tar" and "Additional file archive" can be fed with Tar files that contain paths outside their target directories (e.g., `../../../../tmp/tarslipped2.sh`). When the MOSS cheat checker is started the files inside of the archives are expanded to the attacker-chosen locations. This issue may lead to arbitrary file write within the scope of the running process. This issue has been addressed in version 2.11.0. Users are advised to upgrade.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.