The attack was developed by researchers Juliano Rizzo and Thai Duong, the same pair who last year released details of a similar attack on SSL/TLS and wrote a tool called BEAST, which also gave them the ability to decrypt users' cookies and hijack sessions with sensitive sites such as e-commerce or online banking sites. That attack targeted a specific problem with the AES (Advanced Encryption Standard) algorithm as it was implemented in TLS 1.0 and SSL 3.0 and were able to use the BEAST tool to grab encrypted cookies from active user sessions that were supposedly protected by SSL/TLS.
Once they had the cookie, Rizzo and Duong could return to whatever site the user was visiting and log in using her credentials. The attack caused quite a stir in the security and cryptography communities and browser vendors were forced to issue fixes. One of the workarounds that defeated BEAST (Browser Exploit Against SSL/TLS) was to switch from TLS 1.0 to TLS 1.2 or to switch from AES to the RC4 cipher suite. However, Rizzo said that defense won't work against their new attack, which they've dubbed CRIME."
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