What is Session Hijacking and how to prevent it?

We log into websites and apps all the time, whether it's checking our email, doing online banking, or managing work portals. Each time we log in, a session is created. A session is defined as an interaction with a website from the time you log into your account and ends when you log out. During a session, the website assigns a unique session ID to you, usually stored in cookies or URLs.

Did you know that cyber attackers can hijack this session, steal your session ID, and impersonate you to access your account? This is called session hijacking.

How does session hijacking occur?

Cybercriminals have a few tricks up their sleeve when it comes to hijacking sessions. Here are some of the most common methods:

1. Session Fixation. The attacker forces you to use a session ID they already know, giving them access to your account once you’re logged in.
2. Session Sniffing. They intercept unencrypted communications to steal your session ID.
3. Cross-Site Scripting (XSS). This is a method when malicious scripts are injected into a website to steal your session cookies.
4. Man-in-the-Middle (MITM) Attacks. The attacker intercepts the data between you and the website, including the session information.

How can you prevent session hijacking?

Both website users and administrators play a role in preventing session hijacking. Here are some simple things you can do as an end user to keep your session safe:

1. Log out of accounts. Always log out of websites or applications after use, especially on shared or public devices, to invalidate the session ID.
2. Use HTTPS. Always ensure that the websites you visit use secure connections (HTTPS), especially when transmitting sensitive information. Avoid using websites with insecure HTTP connections, as they are more vulnerable to attacks.
3. Avoid public Wi-Fi. Public Wi-Fi networks are a prime target for attackers. It can be insecure and prone to man-in-the-middle (MITM) attacks, where attackers intercept data, including session information. Consider using VPN (Virtual Private Network) to encrypt your internet traffic.
4. Enable two-factor authentication (2FA). Even if someone gets your session ID, they will still need a second factor (like a mobile verification code) to gain access to your account.
5. Watch out for suspicious links. Be cautious when clicking on links, especially from unknown sources, as attackers can exploit Cross-Site Scripting (XSS) vulnerabilities to steal session data.

6. Clear cookies regularly: Session IDs are often stored in cookies, so clearing them regularly can reduce the risk of session hijacking. This is especially important on shared or public computers.
7. Take cybersecurity training. A great way to help you recognise safe and unsafe websites is to go through an attack simulation training.

As an IT administrator, taking these measures will help protect your user’s session data.

1. Launch training campaigns. If your organisation has Microsoft 365 E5 or Microsoft Defender for Office 365 Plan 2 (add-on license), you can use it to launch training campaigns to run realistic but harmless attack scenarios in your organisation to help identify the most vulnerable users.

2. Set conditional access. Using Microsoft Entra ID, you can ensure that only trusted users, devices, and locations can access your resources. This includes enforcing MFA, blocking risky sign-ins, restricting access based on location, and more.
3. Monitor for suspicious activity. Real-time monitoring for abnormal login behaviour can catch potential hijacking attempts. Microsoft Entra ID Protection provides a dashboard that helps you analyse your security and take action when needed.
4. Use HTTPS everywhere. Enforcing HTTPS on your entire sites encrypts session data and helps prevent hijacking.
5. Implement session timeout. Automatically logging users out after a period of inactivity prevents attackers from exploiting long-lasting sessions.
6. Limit session reuse. Prevent session IDs from being reused across different devices or locations. For example, allow only one active session per user or generate a new session ID after they log in.

Protect your business with Professional Advantage

Session hijacking is a serious cyber threat, but it can be prevented by taking the right security measures. Failure to do so could result in irreparable damage to your organisation’s brand and customer trust and heavy fines under data privacy regulations.

It is more important than ever for organisations to have the skills and knowledge to protect themselves against these types of cyberthreats. If your IT team is struggling to keep up with ever evolving and increasing volume of cyber-attacks, we can help. Our cybersecurity team can work with you to help you identify, assess and mitigate cyber risks. Visit our website or fill out the form on this page to sign up for a free 15-minute consultation to learn how we can help protect your business from cyber threats.