Overview
Session hijacking targets user sessions to gain unauthorized access to user data or even control of the app itself. This vulnerability exploits weakness in how the app is programmed, as well as network vulnerabilities (e.g., unencrypted connections), and user-side issues (e.g., XSS attacks). Session hijacking occurs when attackers steal or manipulate a user's session ID or authentication token, allowing them to take over the user's session without needing their credentials. This attack can be executed via interception of session cookies over unsecured networks, exploiting session management flaws, or leveraging attacks like XSS or CSRF. Once the attacker has control of the session, they can perform any actions the legitimate user can, such as accessing sensitive data or making unauthorized transactions. However, stolen sessions allow attackers to impersonate users temporarily, with access limited to the session’s permissions and duration.
Risk factors
Session hijacking can arise from:
- Transmitting session cookies or tokens over unencrypted HTTP increases the risk of interception.
- Failing to securely generate, manage, or expire session tokens.
- Not regenerating session tokens after a user logs in or during privilege escalation.
- Storing session tokens in an insecure manner, such as in plain text within the app or cookies.
- Lack of secure cookie attributes (HttpOnly, Secure, SameSite).
- Sharing devices or browsers without proper session logout.
Consequences
If an attacker successfully exploits session hijacking, the following could happen:
- Account takeover: Attackers can take control of the user’s account and perform actions like transferring funds or changing account details.
- Data theft: Attackers can access sensitive data or personal information stored in the hijacked session.
- Unauthorized transactions: In financial or e-commerce apps, attackers may make unauthorized purchases or financial transactions using the hijacked session.
- Service abuse: Attackers can misuse the services available to the hijacked session, such as accessing paid features or restricted content.
Solutions and best practices
To mitigate the risks associated with session hijacking, organizations should implement the following security measures:
- Use HTTPS for session cookies: Ensure that session cookies and tokens are transmitted only over HTTPS to prevent interception.
- Secure session management: Implement strong session management practices, such as regenerating session tokens after login and logout, and properly expiring sessions after inactivity.
- Token encryption: Use cryptographically secure methods (e.g., hashing or signing) to generate and validate session tokens, and store them securely.
- Token types: Use short-lived session tokens and refresh tokens for prolonged sessions.
- App shielding: Implement runtime application self-protection (RASP) or similar technologies to detect and prevent session hijacking attempts.
Further reading