Active Session Hijacking: Definition and Examples
What is Active Session Hijacking?
Active session hijacking, also known as session fixation, is a type of cyberattack where an unauthorized person gains control of an authenticated web session while the legitimate user is still logged in. The attacker's goal is to obtain the session identifier or cookie, which they can then use to impersonate the legitimate user, effectively taking over the session without the user's knowledge. This type of attack can have severe consequences as it allows the attacker to access sensitive data or perform actions on the PC or device on behalf of the victim.
Examples of Active Session Hijacking
Session Cookie Theft: In this scenario, an attacker might exploit a vulnerability in the website's security, such as cross-site scripting (XSS), to steal the victim's session cookie. Once they have the cookie, the attacker can use it to authenticate themselves as the victim without logging in, effectively hijacking the session.
Cross-Site Request Forgery (CSRF): In a CSRF attack, an attacker tricks the victim into unknowingly performing actions on a website while they are logged in. For example, the attacker might send a malicious link that, when clicked by the victim, initiates actions like changing the victim's email address or password.
Malicious Browser Extensions: Some browser extensions may be compromised or intentionally designed to steal session cookies. When a user installs such an extension, it could siphon session data and send it to the attacker.
Man-in-the-Middle (MitM) Attacks: In MitM attacks, the attacker intercepts the communication between the user and the server. They can eavesdrop on the session cookies or manipulate the traffic to obtain the session ID.
Session Fixation: In a session fixation attack, the attacker forces the victim to use a particular session ID, often by sending them a malicious link containing a predefined session identifier. Once the victim logs in, the attacker can take over the session.
How to Protect Against Active Session Hijacking
To protect against active session hijacking, web applications often implement security measures such as secure cookies (with the HttpOnly and Secure flags), checking the User-Agent and IP address for consistency during a session, and using anti-CSRF tokens to prevent unauthorized actions initiated by an attacker. Regularly updating and patching web applications and being cautious about browser extensions and unfamiliar links can also help mitigate the risk of active session hijacking.
