Which of the following refers to the exploitation of a valid computer session to gain unauthorized access to information or services in a computer system?

Piggybacking refers to physically following an authorized person through a secured entry point to gain unauthorized physical access to a building or facility, not the exploitation of a computer session.

Hacking is a broad term covering many methods of gaining unauthorized system access and does not specifically describe the targeted exploitation of an existing authenticated session.

Session hijacking exploits a valid, already-established authenticated session - typically by stealing, predicting, or forging a session token - to impersonate a legitimate user and access information or services. The attacker bypasses authentication entirely because the session has already been established, making the stolen token sufficient for access. This precisely matches the definition of exploiting a valid computer session for unauthorized access.

Keystroke logging captures keyboard input to steal passwords or sensitive data as they are typed, which records new input rather than exploiting an existing authenticated session.