Session Hijacking

    skycentral.co.uk | Session Hijacking

    Session Hijacking: An attack where an unauthorized user takes over an established user’s session.

    Session hijacking, also known as session fixation or session sidejacking, is a type of security vulnerability where an attacker illicitly gains control over another user’s web session. The goal of this type of attack is typically to steal sensitive information, impersonate the victim, or perform actions on the victim’s behalf.

    Mechanisms of Session Hijacking

    1. Session ID Capture: One of the primary techniques for session hijacking involves capturing a user’s session ID, which is usually stored in a cookie. This could be done via sniffing unencrypted traffic on an open Wi-Fi network or through other methods like Cross-Site Scripting (XSS).
    2. Man-in-the-Middle Attack: In this scenario, the attacker intercepts communications between client and server to either passively spy on the data or actively manipulate it. SSL/TLS usually helps protect against this but isn’t foolproof.
    3. IP Spoofing: Sometimes the session security relies upon matching the IP address of the client with the IP stored at the time of session initialization. An attacker may use IP spoofing to impersonate the victim’s IP address.


    1. HTTPS: Always use HTTPS for transmitting sensitive information. This encrypts the data, making it harder for attackers to sniff the session ID.
    2. Secure Cookies: Ensure cookies are flagged as secure and make use of HTTPOnly and SameSite attributes to enhance security.
    3. Session Timeout: Implement short session timeout intervals. The shorter the active period of a session, the less time an attacker has to hijack it.
    4. Two-Factor Authentication: Additional layers of authentication can help ensure that even if a session is hijacked, the attacker can’t go further without another form of verification.
    5. Firewalls & IDS: Utilize Intrusion Detection Systems (IDS) and firewalls to monitor and block suspicious activities that could indicate a session hijacking attempt.
    6. Regular Audits: Consistent security audits and vulnerability assessments can help identify new exploits and keep your system updated against them.


    If successful, session hijacking can result in unauthorized access to sensitive information such as passwords, financial data, or personal identification information. This could lead to identity theft, financial loss, or unauthorized changes to important data.

    To sum up, session hijacking is a critical security issue that can have severe consequences. Both web developers and end-users should be aware of this risk and take the necessary precautions to mitigate it.