Security News > 2024 > April > XZ Utils Supply Chain Attack: A Threat Actor Spent Two Years to Implement a Linux Backdoor

A threat actor quietly spent the last two years integrating themself in the core team of maintainers of XZ Utils, a free software command-line data compressor widely used in Linux systems.

The CVE-2024-3094 backdoor found in XZ Utils was implemented to interfere with authentication in SSHD, the OpenSSH server software that handles SSH connections.

How the XZ backdoor was implemented cautiously for more than years.

Finally, several persons responsible for different Linux distributions have been contacted by the attacker to include the backdoored versions of XZ Utils in their own distributions.

Richard WM Jones from RedHat wrote about it on a forum: "Very annoying - the apparent author of the backdoor was in communication with me over several weeks trying to get xz 5.6.x added to Fedora 40 & 41 because of it's 'great new features'. We even worked with him to fix the valgrind issue. We had to race last night to fix the problem after an inadvertent break of the embargo. He has been part of the xz project for 2 years, adding all sorts of binary test files, and to be honest with this level of sophistication I would be suspicious of even older versions of xz until proven otherwise".

Figure A. The backdoor is composed of several parts that have been included over multiple commits on the XZ Utils GitHub, described in depth by Freund.

News URL

https://www.techrepublic.com/article/xz-backdoor-linux/