tar-fs Hardlink Tarball Extraction Arbitrary File Overwrite Vulnerability [CVE-2018-20835]

CVE Number – CVE-2018-20835

A vulnerability in tar-fs could allow a local attacker to overwrite arbitrary files on a targeted system.The vulnerability exists because the affected software improperly validates user-supplied input. An attacker could exploit this vulnerability by extracting a tarball that contains a hard link to a file on the targeted system. A successful exploit could allow the attacker to overwrite arbitrary files on the targeted system.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.The vendor has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement could reduce the likelihood of a successful exploit.

Safeguards

• Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to access local systems.Administrators are advised to allow only privileged users to access administration or management systems.Administrators are advised to monitor critical systems.

Vendor Announcements

• The vendor has released a git commit at the following link: commit 06672828e6fa29ac8551b1b6f36c852a9a3c58a2

Fixed Software

• The vendor has released software updates at the following link: tar-fs releases