An open-source security audit program funded by the U.S. Department of Homeland Security has flagged a critical vulnerability in the X Window System which is used in Unix and Linux systems. Coverity, the San Franciso-based company managing the project under a $1.25 million grant, described the flaw as the "biggest security vulnerability" found in the X Window System code since 2000.
The X Window System, also called X11 or X, provides the toolkit and protocol to build GUIs for Unix and Unix-like operating systems.
Coverity Chief Technical Officer Ben Chelf said the flaw resulted from a missing parenthesis on a small piece of the program that checked the ID of the user. It could be exploited to allow local users to execute code with root privileges, giving them the ability to overwrite system files or initiate denial-of-service attacks.
The flaw was pinpointed during automated code scanning that formed part of the "Vulnerability Discovery and Remediation Open Source Hardening Project," a broad federal initiative to perform daily security audits of approximately 40 open-source software packages, including Linux, Apache, MySQL and Sendmail. The project will also pore over the code bases for FreeBSD, Mozilla, PostgreSQL and the GTK (GIMP Tool Kit) library.
The flaw, which affects X11R6.9.0 and X11R7.0.0, was fixed within a week of its discovery, and Chelf said Coverity has implemented a system to analyze the X Window System on a continuous basis to help prevent new defects from entering the project.