Understanding the Basics: What is Session Hijacking and How Does it Work?

When users log into a website, the server gives them a unique ID for their session. Hackers can use techniques like session sniffing, session fixation, and cross-site scripting (XSS) to gain access to these IDs.

Once they have a valid session, cybercriminals can do virtually anything they want on the network. It can include transferring money, buying merchandise, stealing personal information for identity theft, or encrypting data.

What is Session Hijacking?

Session hijacking is an attack that involves cybercriminals stealing a user’s session ID and impersonating them. The attacker can then take over the victim’s account and access their private information, passwords, or other sensitive data. Cybercriminals use session hijacking to steal money from bank accounts or gain unauthorized access to other systems through SSO.

Cybercriminals can do virtually anything they want during a hijacked session – from purchasing merchandise online to sending personal information or even stealing data from company systems. They can also use hijacked sessions to gain unauthorized access to other applications on the same system (such as Zoom) using an exploit called zoombombing.

Hackers can steal a session ID by sniffing the cookie, intercepting a spoofed request, or tricking the victim into signing in with a fake session ID. These techniques are often used with other attacks, such as cross-site scripting (XSS), session prediction, or session fixation.

When a session is hijacked, the victim’s application may start acting erratically or even crash. It can be a good indication that the session has been compromised. Cybercriminals can also spoof a user’s IP address to make it look like they are in another location. This technique is sometimes used to detect sessions in a particular location and is often recommended along with checking the user-agent string or an attacker’s IP address.

How Does It Work?

A website gives users a unique session ID, which keeps them authenticated to the platform and lets them access their data. Hackers can steal this ID and masquerade as the authenticated user, allowing them to do anything on the site – from intruding on video conferences to stealing passwords and sensitive information, purchasing items, or even encrypting data and demanding a ransom payment to decrypt it.

The attacker gains unauthorized access to the valid session ID by attacking the web application at either the network or application layer using techniques like packet sniffing, brute force, or prediction (a.k.a cookie sniffing or session fixation). For instance, an attacker can try to guess a session ID by analyzing the structure and pattern of the sessions generated by a website’s server, a technique called session prediction.

Another method is to attack the web application through cross-site scripting (XSS). An attacker can execute JavaScript that captures the browser’s session ID by evading the same origin policy and injecting malicious code into a susceptible webpage.

IDS and IPS systems can help prevent this attack by comparing incoming traffic to a database of known attacks to identify anomalies. They can also use threat intelligence to detect unusual patterns and alert system owners of possible breaches. However, these tools are only effective if updated and configured correctly.

How Can You Prevent It?

While video conference takeovers like those in a high school class are getting a lot of attention, the more common type of session hijacking happens at work while people log into their banking apps or online shopping sites. It exposes their sensitive information to data-hungry cybercriminals.

A good security policy is to use a VPN whenever possible to prevent this. It conceals your internet activity, making it much harder for hackers to track your session.

Also, ensure your browser has up-to-date security software. Install and update it regularly; it protects against malware that can sniff for sessions. Many reputable banks, credit card companies, and online stores have safeguards to prevent session hijacking. They have several layers of security set up, such as two-factor authentication (MFA), which necessitates the user entering a code received by SMS or email.

Finally, a critical security strategy is to regenerate session identifiers after login and at critical points in the application. It eliminates the attackers’ ability to reuse a stolen session token because the new session ID differs from the old one. Also, consider limiting the session length for each type of website. For example, a social media app may tolerate more extended sessions. At the same time, a banking or healthcare site may log users out after a few minutes of inactivity to reduce the risk of a hijacked session.

What Are the Most Common Types of Session Hijacking Attacks?

When users log into a site or portal, the server gives them a session ID to identify their account. An attacker can steal this session ID and sign into the site as the authenticated user without detection. It can allow them to commit various types of nefarious acts. They can steal money from the bank account, purchase items, or grab personal data to commit identity theft. Data encryption and ransom demands are also options.

There are several different methods attackers can use to hijack a session, including stealing cookies, brute force, and cross-site scripting. Cross-site scripting attacks exploit security weaknesses in a website, while brute force attacks guess the session ID through trial and error. Session hijacking can also result from an implementation flaw in a platform’s design, such as session fixation.

A simple way to prevent this attack is for websites to use a session ID generator and only send the generated code when needed. Another common approach is checking the user-agent string, often used as a proxy for identifying a user’s machine. However, this is not foolproof. A user’s IP address can change, and many users connect to the internet through wireless access points, cellular networks, or public Wi-Fi. If an attacker is in the same coffee shop as the user, they can monitor their traffic and glean session cookies using packet sniffing.