Demystifying Session Hijacking and Its Threats

To ensure the security of online sessions, it is essential to be aware of session hijacking attacks. Such attacks happen when an unauthorized person gains access to a user’s session token or cookie, allowing them to take control of the session and potentially compromise sensitive data. It is imperative to take appropriate measures to prevent cyberattacks and ensure online safety. It allows the attacker to masquerade as a legitimate website user, potentially causing problems.

Hackers can hijack sessions in various ways, such as sniffing for session IDs and exploiting vulnerabilities. Understanding these various attacks is the first step to staying safe online.

What is a Session Hijacker?

What is session hijacking? A session, as used in many cyber security contexts, is a sequence of exchanges between two endpoints, usually a web server and the user’s browser, during which the browser sends back an identifier known as a session cookie or bearer token to the server. By keeping the user logged in, these cookies either grant access to specific data and actions or let them carry out unauthorized ones.

Cybercriminals use various techniques, depending on their needs and abilities, to take over a user’s session. The easiest and most popular is malware that can watch user web sessions and sniff packets of network traffic. Using this technique, attackers can obtain a session cookie and utilize it to take over a session.

Another technique is to trick the victim into clicking a link that includes their session key. This technique, called session side-jacking, works best on sites that don’t use SSL/TLS for logging in or those with poorly configured Wi-Fi networks. Once an attacker has the session cookie, they can use it to impersonate a user’s account and go on a spree using their saved credit card data.

Having a hacked session also gives the attacker unauthorized access to additional systems that share the same authentication protocol or single sign-on (SSO). As more organizations adopt SSO for their employees, this also raises the risk of attacks on these other systems.

How is a Session Hijacker Identified?

When an internet user visits a website or service requiring logging in, the server applies a session cookie to the browser. This cookie contains information that tells the server what state the user is in. If a cybercriminal steals the cookie, they can impersonate that user and perform access-restricted actions.

For example, a criminal can log in to a person’s bank account and transfer funds or make fraudulent purchases on their behalf. It can cause financial losses and damage a company’s reputation.

As attackers discover new tools for session hijacking, website owners and technology providers work hard to close the loopholes they exploit. For instance, requiring HTTPS across all pages, using secure cookies, and adopting best security practices like regularly updating systems can help reduce the risk of these attacks.

Some cybercriminals simply steal a session cookie by sniffing network traffic or trick the victim into clicking on malicious links containing a predicted session ID. It is sometimes referred to as session hijacking via XSS (cross-site scripting) vulnerabilities, and it works by exploiting the fact that many websites don’t destroy sessions once the user has logged out of them, leaving the cookie in place for an attacker to take over. Other methods of stealing sessions are malware-based. The criminal installs the malware on the victim’s device surveys their system to find a valid session cookie, and then grabs it.

How is a Session Hijacker Done?

When a user logs on to a web platform, the server provides a session identifier (ID) stored in their browser. This ID is used to identify their session in the system and authenticate them to a server without entering a password.

Cybercriminals employ various methods to hijack online sessions and steal sensitive information. Some involve guessing a valid session ID or intercepting an existing one. Others involve exploiting a web application and server vulnerability and injecting client-side code, typically JavaScript.

Once an attacker successfully hijacks a user’s session, they can access the web application or server controls without authentication. The hacker can do anything with the platform, including stealing data, committing fraud, encrypting information, and demanding a ransom.

The most common technique involves using cross-site scripting (XSS) vulnerabilities to inject client-side code, usually in the form of JavaScript, into a webpage. When a compromised page is loaded, the browser executes the code. Criminals then use the code to steal a session ID. Another method, called session fixation, involves creating a phony session ID and tricking the victim into signing in. This scenario may happen when a user mistakenly clicks on a harmful link in an email sent by an attacker.

What Are the Potential Threats?

To secure sensitive information, such as credit card details and personal data, it is essential to implement measures that prevent session hijacking. This proactive approach will protect the website’s reputation and shield users from financial losses and other security risks.

Attackers can also exploit session hijacking to bypass multifactor authentication (MFA), which requires a second, independent form of verification, such as a code sent by SMS or email when users log into websites. It allows hackers to log in without using the victim’s password, allowing them to impersonate the user and access their account with full privileges.

The most common way for attackers to access a session is by stealing the victim’s browser cookie. It is typically done using packet sniffing techniques on public Wi-Fi networks to observe network traffic. Alternatively, attackers may send victims malicious links that contain predicted session IDs and trick them into clicking on them. Once a victim clicks on the link, it installs malware on their device or redirects them to a fake website where they enter their credentials.

For site owners, a compromised session can have serious consequences. They must ensure that all affected users are immediately prompted to change their passwords and that any exploited security loopholes are closed as soon as possible. In addition, they should consider upgrading to custom session handlers that store data more securely and regenerate session IDs after each successful login.