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XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

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Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#161
post #148

Earlier quoted context omitted.

Could you explain how SELinux could ever sandbox against RCE in sshd? Its purpose is to grant login shells to arbitrary users, after all.

It's possible to spawn a sshd as an unprivileged or partially-capabilitized process. Such as sandbox isn't the default deployment, but it's done often enough and would work as designed to prevent privilege elevation above the sshd process.

How can sshd spawn interactive sessions for other users if it's sandboxed?

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#162

Can someone explain succinctly what the backdoor does ? Do we even know yet? The backdoor itself is not a payload, right? Does it need a malicious archive to exploit it? Or does it hook into the sshd process to listen for malicious packets from a remote attacker? The OP makes it sound like an attacker can send a malicious payload in the pre-auth phase of an SSH session - but why does he say that an exploit might neve…

> The OP makes it sound like an attacker can send a malicious payload in the pre-auth phase of an SSH session - but why does he say that an exploit might never be available?

The exploit as shipped is a binary (cleverly hidden in the test data), not source. And it validates the payload vs. a private key that isn't known to the public. Only the attacker can exercise the exploit currently, making it impossible to scan for (well, absent second order effects like performance, which is how it was discovered).

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#163
post #127

Earlier quoted context omitted.

That's the most interesting part. No, we don't know it yet. The backdoor is so sophisticated that none of us can fully understand it. It is not a “usual” security bug.

Yeah these types of security issues will be used by politicians to force hardware makers to lockdown hardware, embed software in chips. The go fast startups habit of “import the world to make my company products” is a huge security issue IT workers ignore. The only solution politics and big tech will chase is obsolete said job market by pulling more of the stack into locked down hardware, with updates only allowed to…

Why would "embed software in chips" be a solution?

If anything, I'd expect it to be an even bigger risk, because when (not if) a security issue is found in the hardware, you now have no way to fix it, other than throwing out this server/fridge/toothbrush or whatever is running it.

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#164

Earlier quoted context omitted.

Is the person Jia who did this PR a malicious actor?

The person who submitted the PR, JiaT75, is. The person who approved and merged it is not.

Yeah that’s what I am asking. Thanks

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#165
post #127

Earlier quoted context omitted.

That's the most interesting part. No, we don't know it yet. The backdoor is so sophisticated that none of us can fully understand it. It is not a “usual” security bug.

Yeah these types of security issues will be used by politicians to force hardware makers to lockdown hardware, embed software in chips. The go fast startups habit of “import the world to make my company products” is a huge security issue IT workers ignore. The only solution politics and big tech will chase is obsolete said job market by pulling more of the stack into locked down hardware, with updates only allowed to…

Which will make updates either expensive or impossible. You will be able to write books about exploitable bugs in the hardware, and those books will easily survive several editions.

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#166

Earlier quoted context omitted.

I felt really bad for the original maintainer getting dog-piled by people who berated him for not doing his (unpaid) job and basically just bring shame and discredit to himself and the community. Definitely cruel. Though… do we know that the maintainer at that point was the same individual as the one who started the project? Goes deep, man.

Even if it's not his fault the maintainer at this point won't be trusted at all. I feel for him, I think even finding a job at this moment for him would be impossible. Why would you hire someone that could be suspected for that?

No. From what I've read on the openwall and lkml mailing lists (so generally people who know a lot more about these things than I do), nobody accused Lasse Collins, the original maintainer, of being involved in this, at all, and there wasn't any notion of him becoming untrustworthy.

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#167
post #127

Earlier quoted context omitted.

That's the most interesting part. No, we don't know it yet. The backdoor is so sophisticated that none of us can fully understand it. It is not a “usual” security bug.

Yeah these types of security issues will be used by politicians to force hardware makers to lockdown hardware, embed software in chips. The go fast startups habit of “import the world to make my company products” is a huge security issue IT workers ignore. The only solution politics and big tech will chase is obsolete said job market by pulling more of the stack into locked down hardware, with updates only allowed to…

The NSA demands that Intel and AMD provide backdoor ways to turn off the IME/PSP, which are basically a small OS running in a small processor inside your processor. So the precedent is that the government wants less embedded software in their hardware, at least for themselves.

If we relied on gadget vendors to maintain such software, I think we can just look at any IoT or router manufacturer to get an idea of just how often and for how long they will update the software. So that idea will probably backfire spectacularly if implemented.

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#169

Earlier quoted context omitted.

I felt really bad for the original maintainer getting dog-piled by people who berated him for not doing his (unpaid) job and basically just bring shame and discredit to himself and the community. Definitely cruel. Though… do we know that the maintainer at that point was the same individual as the one who started the project? Goes deep, man.

Its possible the adversary was behind or at least encouraged the dog piling who berated him. Probably a normal basic tactic from a funded evil team playbook. Might be worth reviewing those who berated him to see if they resolve to real people, to see how deep this operation goes.

This has been investigated and the conclusion is IMO clear: the dogpilling accounts were part of the operation. See the parts about Jigar Kumar in this link: https://boehs.org/node/everything-i-know-about-the-xz-backdo...

Re: XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."

#170

Where is the law enforcement angle on this? This individual/organization needs to be on the top of every country's most wanted lists.

Based on the level of sophistication being alluded to, I'm personally inclined to assume this is a state actor, possible even some arm of the U.S. govt.
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