Malicious code planted in xz Utils has been circulating for more than a month.

The malicious changes were submitted by JiaT75, one of the two main xz Utils developers with years of contributions to the project.

“Given the activity over several weeks, the committer is either directly involved or there was some quite severe compromise of their system,” an official with distributor OpenWall wrote in an advisory. “Unfortunately the latter looks like the less likely explanation, given they communicated on various lists about the ‘fixes’” provided in recent updates. Those updates and fixes can be found here, here, here, and here.

On Thursday, someone using the developer’s name took to a developer site for Ubuntu to ask that the backdoored version 5.6.1 be incorporated into production versions because it fixed bugs that caused a tool known as Valgrind to malfunction.

“This could break build scripts and test pipelines that expect specific output from Valgrind in order to pass,” the person warned, from an account that was created the same day.

One of maintainers for Fedora said Friday that the same developer approached them in recent weeks to ask that Fedora 40, a beta release, incorporate one of the backdoored utility versions.

“We even worked with him to fix the valgrind issue (which it turns out now was caused by the backdoor he had added),” the Ubuntu maintainer said.

He has been part of the xz project for two years, adding all sorts of binary test files, and with this level of sophistication, we would be suspicious of even older versions of xz until proven otherwise.

    • Dark ArcEnglish
      6•9 months ago

      There is a difference from finding something you can take advantage of and putting it there though, no? This sounds like the former.

      But still, it’s a good point, thanks.

      • @[email protected]English
        2•9 months ago

        Ah sorry, english is not my native language so I’m not sure I fully got what you meant, your point was that they stopped inserting backdoors and instead concentrated on getting access by finding vulnerabilities ?

        • Dark ArcEnglish
          3•9 months ago

          Basically two points, they stopped inserting backdoors and their backdoors seem to have only ever been to show them what’s going on (so this just doesn’t look like them to me).

          I didn’t really comment on “what they do now” as much. I think they do continue to spy, finding preexisting vulnerabilities is definitely one way to spy. I wouldn’t be surprised if they report the worst ones in NATO systems to be repaired and keep the others for themselves.

          They also tap into weak points like Google and Apple’s notification services where things aren’t end to end encrypted to gather information. I believe this was revealed recently.

          Snowden I recall saying the modern NSA is more interested in metadata than what’s actually in the message as well.

          In general, I think they still do some shady stuff, but I don’t think they do shady stuff that risks compromising a system. This exploit is quite literally a system compromise as (if I understand it correctly) it allows bypassing sshd authentication.