What is Session Hijacking?
Session Hijacking Definition: An attack where a threat actor takes over a valid user session—often by stealing session cookies—to gain unauthorized access.
Understanding Session Hijacking
Session Hijacking attacks exploit vulnerabilities in how web applications manage user sessions, allowing attackers to steal or forge session identifiers and impersonate legitimate users without needing their credentials. Several techniques exist: sniffing unencrypted traffic to capture session tokens, using cross-site scripting to steal cookies from victims’ browsers, employing session fixation to force users onto attacker-controlled sessions, or exploiting predictable session generation to guess valid identifiers. The impact can be severe—attackers gain the same level of access as the compromised user, potentially viewing sensitive data or performing unauthorized actions. Defending against these attacks requires multiple approaches: enforcing HTTPS to encrypt all traffic containing session information, implementing secure cookie attributes (HttpOnly, Secure, SameSite), utilizing robust session management with unpredictable identifiers, regenerating session IDs after privilege changes like login, and employing proper timeout mechanisms for inactive sessions. Advanced protections include binding sessions to client fingerprints (IP address, user agent, etc.) to detect suspicious changes and implementing continuous authentication that doesn’t rely solely on initial session establishment.