F5 Networks BIG-IP Vulnerability

Exploitation of this may result in a user recovering plaintext versions of encrypted messages or in a Man-in-the-Middle (MitM) attack, despite not having access to the server’s private key. Only Transport Layer Security (TLS) sessions using RSA key exchange are vulnerable. A chosen-ciphertext attack uses ciphertexts and their related decrypted texts to obtain the secret key, by sending nonsensical blocks to be decrypted and analysing the resulting plaintext. The result of this is that not only can messages be decrypted but new messages can be encrypted, affecting the integrity of the messages. An adaptive chosen-ciphertext attack will use the results of previous queries to inform new attempts.

Performing a recovery of the encrypted messages may only allow a user to view the plaintext versions once the session has ended. For a MitM attack to occur, a user would have to generate millions of server requests during the handshake phase of a session before it times out. The limitations on bandwidth and latency, along with the limited window of opportunity makes this attack significantly more difficult to execute.