22.3 Truncation attacks
The TLS record protocol takes each message from the higher layer application protocol (usually HTTP) and protects it with in a single TLS record. TLS may also fragment the message before encrypting it. The TLS security services of integrity and authentication therefore only refer to single messages or their fragments.
In a truncation attack, an attacker acting as man-in-the-middle suppresses complete TLS records or fragments, with the result that client and server become de-synchronized with respect to their current state: For example, a client having sent a logout request to the server assumes that they are logged out. If the logout request is suppressed by Mallory (e.g., by injecting an unencrypted TCP FIN packet), however, the server will continue to assume the client is logged in.
In [167], the authors demonstrate the potential of this kind of attack to take control of Microsoft Live accounts. By using simple traffic analysis, they found out that packets...