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Posted Sep 1, 2011 0:02 UTC (Thu) by dlang (✭ supporter ✭, #313)
yes, it's always possible that there is some black hat out there that has broken it and not told anyone about it, but this is extremely unlikely (the black hat could get rich by just publishing this data, no need to do anything more with it)
In any case, I'm pretty sure that the kernel.org team is going to be double-checking everything by using multiple checksum/hash algorithms and the odds of all of them being able to be bypassed is vanishingly slim
Posted Sep 1, 2011 0:53 UTC (Thu) by lutchann (subscriber, #8872)
Famous, yes, but rich? I suppose you could get a new job with a sexy title and a fat salary, but you'd probably make more money more quickly by keeping your technique a secret and selling it to somebody.
value of zero day versus public reputation
Posted Sep 2, 2011 12:04 UTC (Fri) by copsewood (subscriber, #199)
Posted Sep 1, 2011 0:03 UTC (Thu) by njs (guest, #40338)
Posted Sep 1, 2011 0:05 UTC (Thu) by jonabbey (subscriber, #2736)
No one has demonstrated the ability to find a collision with a pre-existing text in the open literature yet as far as I know. There are techniques to find generate a collision with less than 2^80 operations, but that's still a ways from attacking Git.
Even if someone had the ability to generate a collision with a preimage text, they'd have the secondary task of making the colliding text look reasonable to kernel developers. When people were having fun creating md5 collisions, they tended to have pretty long sequences of random bytes in the text, which would be hard to hide in a kernel source file.
Long story short, it's very unlikely that anyone out there has successfully attacked SHA-1 to the degree necessary to be able to attack the kernel's Git repo. If they had, it's unlikely that they'd have made the kind of mistakes that attracted kernel.org's attention.
Posted Sep 1, 2011 7:04 UTC (Thu) by chax (guest, #52122)
Posted Sep 2, 2011 0:11 UTC (Fri) by BenHutchings (subscriber, #37955)
Posted Sep 2, 2011 2:59 UTC (Fri) by Duncan (guest, #6647)
Basically, in addition to that, you'd have to:
1) Insert the payload into the SAME firmware file (a different file will have its own SHA1, so it's gotta be the same file).
2) Somehow, convince Linus to accept a patch that loads that firmware file, either for your specific target if you have one (not out of the realm of possibility), or for a rather large segment of the kernel running population (rather more difficult, given kernel modularity, but it depends on just how large a segment you want, if everyone running a specific NIC or graphics chip is enough, it's not too difficult, but if you want nearly everyone running a Linux kernel, it's VERY difficult indeed!).
Even if that occurs, you then have to wait until it's actually deployed on your target, with some targets not updating for years, hoping it's not caught in the mean time.
So successful attack via firmware is indeed theoretically possible, but still not particularly simple in practice. There's almost certainly faster and less resource intensive compromise methods, so it's unlikely to be used in practice.
Posted Sep 2, 2011 5:49 UTC (Fri) by joey (subscriber, #328)
Posted Sep 1, 2011 5:47 UTC (Thu) by iabervon (subscriber, #722)
Posted Sep 1, 2011 7:21 UTC (Thu) by raalkml (guest, #72852)
See http://git-blame.blogspot.com/2011/08/how-to-inject-malic... for details
Posted Sep 2, 2011 5:52 UTC (Fri) by joey (subscriber, #328)
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