In wolfSSL version 5.3.0, man-in-the-middle attackers or a malicious server can crash TLS 1.2 clients during a handshake. If an attacker injects a large ticket (above 256 bytes) into a NewSessionTicket message in a TLS 1.2 handshake, and the client has a non-empty session cache, the session cache frees a pointer which points to non-allocated memory, causing the client to crash with a “free(): invalid pointer”. Note: It is likely that this is also exploitable in TLS 1.3 handshakes between a client and a malicious server. With TLS 1.3 it is not possible to exploit this as a man-in-the-middle. This bug was discovered using the novel symbolic-model-guided fuzzer tlspuffin. Continue reading...
