BEAST
/biːst/
n. “The cipher’s hungry monster that chews SSL/TLS.”
BEAST, short for Browser Exploit Against SSL/TLS, is a cryptographic attack discovered in 2011 that targeted vulnerabilities in the SSL 3.0 and TLS 1.0 protocols. Specifically, it exploited weaknesses in the way block ciphers in Cipher Block Chaining (CBC) mode handled initialization vectors, allowing attackers to decrypt secure HTTPS cookies and potentially hijack user sessions.