Ten-Year-Old Sudo Vulnerability Gives Root Privileges on Host

A major security hole in the Sudo utility could be abused by unprivileged users to gain root privileges on the vulnerable host, Qualys reports.

Designed to allow users to run programs with the security privileges of another user (by default superuser, hence the name, which is derived from ‘superuser do’), Sudo is present in major Unix- and Linux-based operating systems out there.

Tracked as CVE-2021-3156, the recently identified vulnerability, which Qualys refers to as “Baron Samedit,” was introduced in July 2011, and can be exploited to gain root privileges using a default Sudo configuration.

This means that an attacker able to compromise a low-privileged account on the machine could abuse the vulnerability to gain root access.

All legacy versions of Sudo, from 1.8.2 to 1.8.31p2, as well as the utility’s stable releases from 1.9.0 to 1.9.5p1 are affected, in their default configuration.

Qualys’ security researchers said they came up with exploit variants to obtain full root privileges on Linux distributions such as Debian 10 (Sudo 1.8.27), Fedora 33 (Sudo 1.9.2), and Ubuntu 20.04 (Sudo 1.8.31), but noted that other operating systems and distributions that rely on Sudo might be affected as well.

The bug was reported to the Sudo team a couple of weeks ago, and patches were rolled out today. Sudo v1.9.5p2 resolves the vulnerability.

“Given the breadth of the attack surface for this vulnerability, Qualys recommends users apply patches for this vulnerability immediately,” the security researchers note.

Qualys, which provides an in-depth technical analysis of the vulnerability, has published a proof-of-concept video to demonstrate how the issue can be exploited.

Last year, a buffer overflow in the pwfeedback option in Sudo was also found to provide attackers with elevated privileges on an affected machine. Several years ago, another privilege escalation bug was addressed in the popular utility.

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