an attack that hijacks a valid user session. An attacker attempts to lure a user to authenticate himself or herself with a known session ID and then hijacks the user-validated session with the knowledge of the used session ID

• A. Session Fixation Attack
• B. Session Hijacking
• C. Man-in-the-Browser Attack
• D. CSRF Attack

Answer: (A)

Session fixation is being tested here. In this attack, the attacker provides or forces a known session identifier before the user logs in and tricks the user into authenticating with that session ID. After authentication, the server associates that same pre-set session with the user, allowing the attacker to hijack the session simply by using that known ID to access the account later. Defense lies in preventing pre-issued IDs from being used at login—generate a fresh session ID on authentication, invalidate old ones, and use secure cookie practices.

Why the others don’t fit: session hijacking involves stealing an already active session token to take over a session, not forcing the user to login with a pre-known ID. CSRF relies on tricking a user into performing actions in a valid session without taking over the session token itself. Man-in-the-browser involves malware inside the user’s browser to capture credentials or sessions, not the pre-login session fixation scenario.