Session hijacking is the abuse of a valid user session so an attacker can act as the user without needing the original password. It matters because modern applications often rely heavily on session tokens, cookies, and authenticated browser state.
What is Session Hijacking?
After a user authenticates, many systems issue a session token or cookie that represents the active login state. If an attacker steals, reuses, or manipulates that session state, they may be able to impersonate the user without repeating the initial login flow.
Session hijacking can happen through malware, browser compromise, man-in-the-middle activity, insecure storage, token theft, or web application flaws that expose session material.
How Session Hijacking Commonly Happens
Common causes include stolen session cookies, insecure transport, cross-site scripting, token leakage, browser compromise, phishing proxies, and weak session expiration or invalidation behavior.
Session Hijacking vs. Account Takeover
Session hijacking is one path to acting as a user by abusing active session state. Account takeover is the broader outcome of gaining control over an account through credentials, sessions, or other access mechanisms.
Frequently Asked Questions
Can session hijacking bypass MFA?
Yes. If an attacker steals a live authenticated session after MFA is completed, they may be able to act without repeating the MFA challenge.
How can defenders reduce session hijacking risk?
Secure session handling, short-lived tokens, reauthentication for sensitive actions, device and context checks, phishing-resistant login flows, and protection against XSS all help reduce risk.
