My colleague, Bodo M¶ller, in collaboration with Thai Duong and Krzysztof Kotowicz (also Googlers), just posted details about a padding oracle attack against CBC-mode ciphers in SSLv3. This attack, called POODLE, is similar to the BEAST attack and also allows a network attacker to extract the plaintext of targeted parts of an SSL connection, usually cookie data. Unlike the BEAST attack, it doesn’t require such extensive control of the format of the plaintext and thus is more practical. Fundamentally, the design flaw in SSL/TLS that allows this is the same as with Lucky13 and Vaudenay’s two attacks: SSL got encryption and authentication the wrong way around – it authenticates before encrypting.