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Meltdown Proof-of-Concept

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51–60 of 187 posts

Re: Meltdown Proof-of-Concept

#51
I have run the first test on several machines, with mixed results, but on my workhorses (ThinkPad x220, Zenbook UX305) the exploit seems to work.

I thought the recent kernel-/firmware-/ucode-patches should have prevented that.

EDIT: The other demos fail, though, as they should. sigh

EDIT: For some reason, demo #2 (breaking kaslr) works on my Ryzen machine, but not on the others. :-?

Re: Meltdown Proof-of-Concept

#52
post #15
post #14

Earlier quoted context omitted.

I wonder what happened to "This bug is subject to a 90 day disclosure deadline. After 90 days elapse or a patch has been made broadly available, the bug report will become visible to the public." Executive meddling? Edit: Probably the 'extreme circumstances' bit mentioned in https://news.ycombinator.com/item?id=16108434

I think for a bug this big it is pretty understandable. So far, it seems clear the actions of all involved were in a good spirit of responsible disclosure.

Re: "responsible disclosure": https://news.ycombinator.com/item?id=9945686

Just something to keep in mind, not something we need to litigate on this thread.

Re: Meltdown Proof-of-Concept

#53
From the papers, these two bugs are also exploitable from ARM.

Does it mean a hacked IOS/Android app can also (in theory) sniff the password enter in system dialog as demo in the video?

   Realtime password input - https://www.youtube.com/watch?v=yTpXqyRYcBM

Re: Meltdown Proof-of-Concept

#54

Earlier quoted context omitted.

If you don't know the difference between the existence of an earthbound asteroid and the existence of people who write computer viruses, I don't know what to tell you.

What's the name for this logical fallacy? You see this shit all the time.

Probably false analogy.

Re: Meltdown Proof-of-Concept

#55
post #13
post #12

Earlier quoted context omitted.

> "read any physical memory" as "read memory in cache" You can force values from any memory to affect the cache in a predictable manner which enables you to read all physical memory. See https://news.ycombinator.com/item?id=16108574 or read the paper yourself https://meltdownattack.com/meltdown.pdf

> You can force any memory into the cache so yes it's is read any physical memory. Is there a direct method for that or do you mean that you can repeatedly try reading memory addresses until the address that you want to access is actually in the cache prior to your access?

The relationship between the attacker and cache is fundamental to the attack; the Meltdown paper does a really good job explaining this.

Re: Meltdown Proof-of-Concept

#56
libkdump is really clean code and worth a read, nicely wrapping the inline assembly you need to do the flush+reload and keeping the algorithms in pretty simple C. It's worth taking a few minutes to read through it.

This code is from TU Graz; I assume this is from Daniel Gruss's team, who participated in the original research.

Re: Meltdown Proof-of-Concept

#57
post #53

From the papers, these two bugs are also exploitable from ARM. Does it mean a hacked IOS/Android app can also (in theory) sniff the password enter in system dialog as demo in the video? Realtime password input - https://www.youtube.com/watch?v=yTpXqyRYcBM

It depends. From what I'm reading: generally, with apparently one possible exception, Meltdown doesn't work on ARM. Generally, both variants of Spectre do.

Re: Meltdown Proof-of-Concept

#58

The secret program confirms what others have seen, it's not so much "read any physical memory" as "read memory in cache"

The entire point of the attack is that attackers can coerce targets to predictably load things into cache, which is why you're being downvoted. You should re-read the Meltdown paper; it's very clear (and significantly easier to read than the Project Zero writeup, which is good but goes deep into implementation details).

Re: Meltdown Proof-of-Concept

#59
post #14

The Project Zero bug report (with PoCs/timeline) was also made public a few minutes ago https://bugs.chromium.org/p/project-zero/issues/detail?id=12...

I wonder what happened to "This bug is subject to a 90 day disclosure deadline. After 90 days elapse or a patch has been made broadly available, the bug report will become visible to the public." Executive meddling? Edit: Probably the 'extreme circumstances' bit mentioned in https://news.ycombinator.com/item?id=16108434

The embargo date agreed among the several teams that were working on this was today, the 9th.

Re: Meltdown Proof-of-Concept

#60

Earlier quoted context omitted.

Except if you are into *BSD. In that case you might want to label it "selective disclosure" instead of "responsible disclosure".

Well, since some of the BSD folks publicly stated that they’d ignore any embargo, that seems like a pretty predictable consequence. And in this case I understand that it took a while to develop workable mitigations. Immediate disclosure might have caused great harm.

Tarring all of the BSDs with the same brush is wrong, both in general and here specifically. There's also the matter of both Matthew Dillon and Theo de Raadt discussing this topic months or even years before Google Project Zero made its discovery.

* https://news.ycombinator.com/item?id=16086047

* https://news.ycombinator.com/item?id=16074531

* https://news.ycombinator.com/item?id=16075744

Moreover, the OpenBSD people have made some remarks about how it was commentaries in Linux patches and discussions on LWN that actually let the cat out of the bag this time.

* http://pythonsweetness.tumblr.com/post/169166980422/the-myst... (https://news.ycombinator.com/item?id=16046636)

* https://news.ycombinator.com/item?id=16084404

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