What is Session Hijacking?

Session hijacking is a prevalent and dangerous attack method frequently employed by cybercriminals to illicitly gain access and then take control of user accounts and systems. Session hijacking is a type of cyberattack where an attacker gains unauthorized access to a user’s active online session, allowing them to impersonate the legitimate user and perform malicious actions.

While the exact prevalence of session hijacking is difficult to quantify, it is considered a significant and growing threat to web application security that organizations must address through proper security measures.

Here’s a quick overview of how session hijacking works:

• When a user logs into a website or application, the server creates a session for the user, typically by issuing a session ID stored in a cookie or URL.
• The attacker intercepts the user’s session ID, either by eavesdropping on the network traffic (passive session hijacking) or by exploiting vulnerabilities like cross-site scripting to steal the session ID (active session hijacking).
• With the stolen session ID, the attacker can impersonate the legitimate user and access the user’s account, perform unauthorized actions, steal sensitive information, or launch further attacks.

The three main types of session hijacking attacks are cross-site scripting (XSS), where the attacker injects malicious scripts into web pages to steal the user’s session ID; session sniffing/side-jacking, where the attacker monitors the network traffic to intercept the user’s session ID and session fixation where the attacker tricks the user into using a session ID controlled by the attacker. However, there are other methods, and we will explore them below.

The prevalence of session hijacking is increasing, although pinpointing it can be challenging as the attackers look like legitimate users. Attackers are posting about it increasingly on dark web forums and cybercrime networks. It is one of the most popular methods attackers use to gain unauthorized access to user accounts and systems. Threat actors can execute session hijacking attacks through various techniques, including session sniffing, session fixation, XSS, and malware exploitation. The abundance of active sessions on networks that experience heavy traffic provides ample opportunities for attackers to carry out session hijacking exploits. Session hijacking attacks can have severe consequences, allowing attackers to impersonate legitimate users and perform malicious actions such as accessing sensitive data, transferring funds, or launching further attacks.

Failing to take measures to prevent session hijacking poses numerous risks, including:

• Theft of Personal Information: Session hijacking grants hackers access to sensitive data like passwords and credit card numbers, paving the way for identity theft or financial fraud.
• Denial-of-Service (DoS) Attacks: Hackers who hijack a user’s session can execute DoS attacks against the connected website or server. This malicious act disrupts service availability or may even crash the targeted site.
• Malware Infection: If a hacker obtains a user’s session ID, they may inject malware into the user’s system, enabling them to seize control of the user’s computer and pilfer valuable data.

The methods used for session hijacking are:

• Session Sniffing: Attackers use network sniffers or proxies to intercept and capture the user’s session ID as it is transmitted between the user and the server.
• Session Fixation: The attacker tricks the user into using a predetermined session ID, allowing the attacker to take control of the session once the user logs in.
• Cross-Site Scripting (XSS): The attacker injects malicious scripts into web pages to steal the user’s session ID.
• Malware: Malware installed on the user’s device can covertly modify transactions and initiate additional actions without the user’s knowledge, hijacking the active session.
• Brute Force: Attackers attempt to guess or deduce the session ID, primarily if it is generated using easily predictable patterns or variables.
• Man-in-the-Browser: Like a man-in-the-middle attack, the attacker infects the victim’s device with malware to intercept and modify the session data.
• Session Sidejacking: The attacker intercepts session data while in transit, often by exploiting weak or lack of encryption.

To prevent session hijacking, it is crucial to deploy basic security practices such as making users use strong passwords, creating unpredictable session IDs, implementing proper encryption, enabling multi-factor authentication, and keeping software up-to-date to patch vulnerabilities.

Key Points

• Definition: Session hijacking involves unauthorized access to an active online session, enabling attackers to impersonate legitimate users and conduct malicious activities.
• Prevalence: While precise statistics are challenging to ascertain, session hijacking is recognized as a significant and escalating threat to web application security, necessitating appropriate security measures.
• Mechanisms: Attackers intercept a user’s session ID through passive session hijacking (eavesdropping on network traffic) or active session hijacking (exploiting vulnerabilities like cross-site scripting).
• Risks: Session hijacking poses severe risks, including identity theft, financial fraud, denial-of-service (DoS) attacks, and malware infection on users’ systems.

Here are some of the best practices for preventing session hijacking:

• Use Secure Protocols: Employ HTTPS and the latest versions of TLS to encrypt the communication between the user and the server, thwarting session ID interception.
• Implement Multi-Factor Authentication (MFA): MFA is an authentication method that requires the user to provide another verification factor to gain access to an account. MFA creates an extra layer of security, but even when MFA is in place, it is critical organizations still force users to use uncompromised passwords.
• Monitor User Passwords: Monitor user passwords or credentials for weakness or compromise. Products like Enzoic can monitor user passwords continuously for compromise and restrict users from selecting unsafe passwords during account setup. Paired with MFA, passwords are still the first level of defense from attackers and can keep the account secure if the attacker manages to steal a user’s session ID.
• Manage Session IDs Properly: Generate random, unpredictable session IDs that cannot be easily guessed or brute-forced. Refresh session IDs regularly after login, logout, or other sensitive actions to prevent session fixation attacks. Store and transmit session IDs securely using cookies with the Secure, HttpOnly, and SameSite attributes.
• Deploy Timeout and Logout Features: Automatically end user sessions after a period of inactivity to reduce the window of opportunity for session hijacking. Give users an easy way to log out and terminate their session manually.
• Monitor and Audit Sessions: Track user session activity for anomalies and unauthorized access attempts, reviewing logs and alerts regularly. Review alerts for any anomalies or unauthorized access attempts.
• Educate Users: Educate users on session hijacking risks and mitigation strategies, encouraging proactive reporting of suspicious activity. Educate them on using strong passwords, avoiding public networks, and logging out properly. Encourage users to report any suspicious activity or security incidents they witness in their systems.
• Keep Software Up to Date: Regularly update web applications, servers, and third-party components to patch known vulnerabilities.
• Implement Web Application Firewalls (WAFs): Employ WAF tools to filter malicious traffic and block common session hijacking vectors.

By adhering to these best practices, organizations can significantly reduce the risk of session hijacking and safeguard user accounts and data effectively.