CVE-2024-3094
Xz: malicious code in distributed source
What happened?
Malicious code was discovered in the upstream tarballs of xz, starting with version 5.6.0. Through a series of complex obfuscations, the liblzma build process extracts a prebuilt object file from a disguised test file existing in the source code, which is then used to modify specific functions in the liblzma code. This results in a modified liblzma library that can be used by any software linked against this library, intercepting and modifying the data interaction with this library.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| xz | affected: 5.6.0; affected: 5.6.1 | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
| xzRed Hat | Default status: unaffected | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2024-3094
- https://access.redhat.com/security/cve/CVE-2024-3094
- https://bugzilla.redhat.com/show_bug.cgi?id=2272210
- https://www.openwall.com/lists/oss-security/2024/03/29/4
- https://www.redhat.com/en/blog/urgent-security-alert-fedora-41-and-rawhide-users
- https://www.binarly.io/blog/persistent-risk-xz-utils-backdoor-still-lurking-in-docker-images
- https://ariadne.space/2024/04/02/the-xz-utils-backdoor-is-a-symptom-of-a-larger-problem/
- https://arstechnica.com/security/2024/03/backdoor-found-in-widely-used-linux-utility-breaks-encrypted-ssh-connections/
- https://aws.amazon.com/security/security-bulletins/AWS-2024-002/
- https://blog.netbsd.org/tnf/entry/statement_on_backdoor_in_xz
- https://boehs.org/node/everything-i-know-about-the-xz-backdoor
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1068024
- https://bugs.gentoo.org/928134
- https://bugzilla.suse.com/show_bug.cgi?id=1222124
- https://discourse.nixos.org/t/cve-2024-3094-malicious-code-in-xz-5-6-0-and-5-6-1-tarballs/42405
- https://gist.github.com/thesamesam/223949d5a074ebc3dce9ee78baad9e27
- https://github.com/advisories/GHSA-rxwq-x6h5-x525
- https://github.com/amlweems/xzbot
- https://github.com/karcherm/xz-malware
- https://gynvael.coldwind.pl/?lang=en&id=782
- https://lists.debian.org/debian-security-announce/2024/msg00057.html
- https://lists.freebsd.org/archives/freebsd-security/2024-March/000248.html
- https://lwn.net/Articles/967180/
- https://news.ycombinator.com/item?id=39865810
- https://news.ycombinator.com/item?id=39877267
- https://news.ycombinator.com/item?id=39895344
- https://openssf.org/blog/2024/03/30/xz-backdoor-cve-2024-3094/
- https://research.swtch.com/xz-script
- https://research.swtch.com/xz-timeline
- https://security-tracker.debian.org/tracker/CVE-2024-3094