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.

  • @TheKMAPEnglish
    11•3 months ago

    Have those audits you allude to ever caught anything before it went live? Cuz this backdoor has been around for a month and RedHat is affected, too. Plus this was the single owner of a package who is implicitly trusted, it’s not like it was a random contributor whose PRs would get reviewed.

    The code being open source helps people track it down once they try to debug an issue (performance issue and crashes because in their setup the memory layout was not what the backdoor was expecting), that’s true. But what actually triggered the investigation was the bug. After that it’s just a matter of time to trace it back to the backdoor. You understimate reverse engineers. Or maybe I’m just spoiled.

    How long until US bans code from developers with ties to CN/RU?

    • Teppic
      5•3 months ago

      How long until US bans code from developers with ties to CN/RU?

      That won’t happen because it would effectively mean banning all FOS which isn’t remotely practical.

      • @TheKMAPEnglish
        2•3 months ago

        How do you propose we meaningfully fix this issue? Hoping random people catch stuff doesn’t count.

        • Cosmic ClericEnglish
          2•3 months ago

          An open source project that does nothing but security audits on other open source projects?

        • Teppic
          1•3 months ago

          In time it may become a trade-off between new (with associated features and speed) Vs tried and tested/secure.
          To us now this sounds perverse, but remember that NASA generally use very old hardware because they can be more certain the various bugs & features have been found and documented. In NASA’s case this is for reliability. I’ll concede ‘brute force’ does add another dimension when applying this logic to security.

          This may also become an AI arms race. Finding exploits is likely something AI could become very good at - but a better AI seeking to obfuscate?