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.
Vulnerabilities are caught and fixed faster in open source projects than closed ones.
The researchers found that open-source programmers fixed Linux issues in an average of only 25 days. In addition, Linux’s developers have been improving their speed in patching security holes from 32 days in 2019 to just 15 in 2021.
Its competition didn’t do nearly as well. For instance, Apple, 69 days; Google, 44 days; and Mozilla, 46 days.
Coming in at the bottom was Microsoft, 83 days, and Oracle with 109 days.
By Project Zero’s count, others, which included primarily open-source organizations and companies such as Apache, Canonical, Github, and Kubernetes, came in with a respectable 44 days.
