this post was submitted on 01 Apr 2024
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Hey, I've been hearing a LOT about the xz backdoor. Crazy story, but rather than reading 10 different articles about it from 3 days ago when the story was quite new, does anybody know a high quality write-up that has all the juicy details and facts? I really like in-depth guides that cover every aspect of the story.

Thanks in advance guys!

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[–] [email protected] 54 points 8 months ago* (last edited 8 months ago) (1 children)
[–] [email protected] 7 points 8 months ago (1 children)

That's way more steps than I thought

I wonder if something so complex makes it easier to potentially detect than something slightly simpler.

Btw what does the .o file do, is that the one running inside ssh through system d?

[–] [email protected] 4 points 8 months ago (2 children)

I am by far an expert, but imo it seems it needed to be complex to achieve its goals, and to get that level of change in without notice required breaking it down and sneaking pieces in over time.

Happy to be corrected of course if this is a wrong interpretation

[–] [email protected] 9 points 8 months ago (1 children)

You're correct. Right now many experts are scrambling all those small pieces together as to how this could happen in the first place, as a lot of it was public too: the social pressure on maintainers, random software changes that now seem suspicious, and the absence of a real identity of the perpetrators. Every expert who's onto this seems to be a real person, with a real identity and a real face to the name.

Prior to the first commits, there must have been months if not years of planning too.

But just the fact that some of the code those perpetrators wrote took +0.5 seconds more for something that would normally only take 0.2-0.3 seconds is what gave them away.

0.5 seconds of CPU time vs. years of planning.

It's an intriguing story.

They tried so hard, they got so far, but in the end, it didn't even matter.

[–] [email protected] 1 points 8 months ago

I wonder exactly why ssh was taking so long more. Perhaps the bits that scan ssh logs with a regex to extract IP address and username?

Whatever it is, that particular bit should be easy to deactivate since somehow a full fledged binary file with executable code was being bundled. I can imagine it only being active under a toggle that would make it harder to detect, such as a specific time of day.

[–] [email protected] 1 points 8 months ago

That's my take as well