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by tptacek 5750 days ago
No, Rails encrypts then signs, which means it verifies HMAC before it CBC-decrypts the message. It isn't vulnerable to this attack. What led you to say that it was?

JSF was vulnerable to this attack; Thai and Juliano, the researchers that other HN users are trashing on this thread, also found that flaw as well. I have to assume it's been fixed by now.
1 comments
thinkzig 5750 days ago
What led you to say that it was?

Section 5.1 of this whitepaper[1] by Rizzo and Duong, that lists Ruby on Rails as one of the web frameworks vulnerable to this attack.

Granted, this paper was published in May, and I'm not a Rails guy, so it's quite possible this has been patched as well.

[1]http://usenix.org/events/woot10/tech/full_papers/Rizzo.pdf

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tptacek 5750 days ago
Their comment about MessageEncryptor is accurate, but I don't believe the bare #encrypt (which could create a vulnerability if exceptions weren't laundered) is used anywhere. Rails sessions are encrypted and then HMAC'd. This pattern isn't susceptable to padding side channels.
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