Definition
Session hijacking, also known as session sidejacking, is a cyberattack where an attacker takes control of a legitimate user's active session with a web application. This is typically achieved by stealing the session token, which is a piece of data that identifies a user's session to the server. Once the attacker has the session token, they can impersonate the user and gain unauthorized access to their account and data without needing to know the user's credentials. This poses a significant risk to data privacy and system integrity. For instance, an attacker might capture a session cookie transmitted over an unencrypted network connection. This attack differs from credential stuffing, which involves using stolen usernames and passwords. Understanding session hijacking is crucial for cybersecurity professionals and is covered in certifications like CompTIA Security+ and CySA+.