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Everything I know about the XZ backdoor

  • Everything I know about the XZ backdoor

    This has been the most exciting security event in years. The xz compression library was compromised, in a very specific and careful way, involving years of a “long game”, seemingly to allow remote code execution via crafted public key material, to the OpenSSH sshd: “It is a RCE backdoor, where sshd is used as the first step: It listens for connections, and when so patched, invokes the malignant liblzma, which in turn executes a stage 2 that finally executes the payload which is provided to sshd in a part of the encrypted public key given to it as the credential (which doesn’t need to be authentic to be harmful).” (gentoo bug 928134) More info: I hope this drives less use of complex transitive dependency chains in security critical software like OpenSSH. Careful “vendoring” of libraries, and an overall reduction of library code (djb-style!) would help avoid this kind of attack…. if it’s ever really possible to avoid this kind of state-level attack sophistication. I have to send my sympathies to Lasse Collin, the original maintainer of xz-utils, who it appears was conned into passing control to an attacker intent on subverting the lib in order to plant the backdoor. Not a fun spot to be in.

    (tags: oss open-source security openssh ssh xz backdoors rce lzma transitive-dependencies)



    DOOM is now running IN SPACE, onboard the ESA OPS-SAT satellite. “How We Got Here — A vision brewing for 13 years: 2011: Georges [Labreche] stumbles on what would become his favorite SMBC comic, thank you Zach! 2020: Georges joins the OPS-SAT-1 mission control team as a Spacecraft Operations Engineer at the European Space Agency (ESA). Visions of running DOOM on a space computer intensifies. 2023: The reality of a 2024 end-of-mission by atmospheric re-entry starts to hit hard. The spacecraft’s impending doom (see what I did there?) is a wake-up call to get serious about running DOOM in space before it’s too late. 2024: Georges has been asking around for help with compiling and deploying DOOM for the spacecraft’s ARM32 onboard computer but isn’t making progress. One night, instead of sleeping, he is trapped doomscrolling (ha!) on Instagram and stumbles on a reel from ├ôlafur [Waage]’s “Doom on GitHub Actions” talk at NDC TechTown 2023: Playing Video Games One Frame at a Time. After sliding into the DM, the rest is history.”

    (tags: esa ops-sat-1 doom space hacks via:freqout)