Most organizations have strong mechanisms for authenticating users. However, hackers can bypass these techniques and take control of a user’s online session. Session hijacking attacks are a serious threat that can result in significant financial losses and reputational damage.
Session hijacking attacks have increased dramatically in recent years as organizations use more cloud-based applications. Microsoft detected 147,000 token replay attacks targeting cloud-based enterprise environments in 2023, a 111 percent increase over the previous year. Experts say Attacks on session cookies now occur at a similar rate to password-based attacks.
Unlike brute force attacks, however, session hijacking doesn’t involve stolen login credentials, making it harder to spot until the damage has been done. Organizations need to be aware of the various types of these attacks and be prepared to respond quickly to mitigate the risk.
What Is Session Hijacking?
Applications and websites use session IDs (often stored as cookies) to track a user’s login status and activity during a session. In a session hijacking attack, hackers use various techniques to either steal the session ID or predict a valid session ID. This allows the attacker to gain unauthorized access to the user’s active session and potentially steal sensitive data or commit fraud.
In a man-in-the-middle attack, hackers monitor user activity to intercept session tokens, often using an unsafe Wi-Fi connection or a compromised network device. When the user logs into an account, the authenticated session token is exposed. The hacker then steals the token to gain access to the account.
There are several types of man-in-the-middle attacks. In a session sidejacking attack, hackers use packet sniffing tools to monitor data transmissions and intercept session cookies from unencrypted traffic. Hackers may also “spoof” an IP address to impersonate a legitimate user or server (IP spoofing), or redirect traffic to fake websites by injecting false information into a server’s cache (DNS cache poisoning).
Active Session Hijacking Attacks
Hackers may also use more active techniques in session hijacking attacks. With cross-site scripting, hackers exploit vulnerabilities in some web applications to inject malicious code into trusted websites. The user’s browser believes it to be a trusted source and returns the session token to the hacker. A man-in-the-browser attack infects the user’s browser with malware that allows the hackers to intercept and manipulate session data.
Some attacks use phishing to gain access to session tokens. Cookie theft attacks trick users into revealing their login credentials on fake websites or applications, allowing the attacker to access session tokens. In a session fixation attack, the hacker sends a link to the target website that already contains a known token, giving the attacker access to the user’s account.
Session token prediction attacks don’t involve the theft of an authenticated session token. Instead, the hacker analyzes the session token structure to predict what a valid token would look like. The hacker then tries possible IDs until one is successful. AI makes this process faster and easier.
Detecting and Preventing Session Hijacking
Detecting session hijacking can be difficult, but there are often clues that an attack has occurred. Sudden changes in location or IP address during a session or concurrent sessions from different locations can indicate a session hijacking attack. Organizations should use intrusion detection systems to monitor for these kinds of anomalies and detect deviations from normal user behavior.
Organizations can prevent session hijacking by generating strong, random session IDs that are difficult to guess. They should also set short session timeouts for inactivity and regenerate session IDs after login and whenever privileges change to prevent session fixation attacks. Multifactor authentication is not a complete safeguard against session hijacking, but it makes it harder for attackers to gain initial access.
The Cerium security team is here to help you detect and prevent session hijacking. Our experts can conduct vulnerability assessments to identify weaknesses in session management, and continuously monitor network traffic and user activity for anomalies that might indicate session hijacking attempts. We can also help you select and implement tools that ensure strong authentication. Let us help you reduce the risk of a costly session hijacking attack.
