Best article about XZ backdoor?

Linux@lemmy.ml – 109 points – 6 months ago

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!

Original Mastodon post by Andres Freund about discovery

Original Openwall thread

Update by @dangoodin@infosec.exchange

JFrog article

Bluesky post by another person

Hacker News article

Update by the original maintainer

Wikipedia Article

Original Mailing history

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?

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

That's my take as well

2 more...

Not everything is known yet, so you won't find a comprehensive summary. The latest news I've seen: https://www.openwall.com/lists/oss-security/2024/03/30/36

I'm watching some folks reverse engineer the xz backdoor, sharing some preliminary analysis with permission. The hooked RSA_public_decrypt verifies a signature on the server's host key by a fixed Ed448 key, and then passes a payload to system(). It's RCE, not auth bypass, and gated/unreplayable.

All the technical details that are widely known (and some that aren't yet) seem to be in that thread, including the original report from Andres Freund. For rumours about who might be behind it and high-level speculation about what it all means, you'd have to look elsewhere.

thx :)

https://boehs.org/node/everything-i-know-about-the-xz-backdoor gives a good overview with links to further reads.

awesome, thanks!

Sam Jones's FAQ is by far the best single source, links to other solid sources for more in-depth technical details and also lightly debunks a few things.

The main thing sources online disagree on are which distros are affected. That's because it's not a simple yes/no and some distros are taking a nuanced approach in their public communication, while others have chosen the sledgehammer in an attempt to get people to upgrade their systems but keep/kept the nuance in the back room where the audience understood not everything was known yet. Some distros are underselling how vulnerable they were, others are overselling it.

Best coverage I've seen so far has been on Ars Technica.

Yeah, their original coverage was good, but they also had a really good follow up today.

thanks!

I read a few articles. I think Andres Freund's announcement gave me the best context for the exploit itself. https://www.openwall.com/lists/oss-security/2024/03/29/4

The most helpful source I saw on which systems are affected was this Lemmy post, https://beehaw.org/post/12813772

It's still ongoing and still being reverse engineered, so I would expect the good writeups to come in a couple days.