What Is Session Hijacking and How Do You Prevent It?

Session hijacking is a cyber attack where cybercriminals intercept and steal the session ID, also referred to as a session token, shared between a user and a website. With a stolen session ID, a cybercriminal can pretend to be the user and gain access to their account. To prevent session hijacking, website owners need to use HTTPS across their entire website and strengthen session management. Website visitors can prevent session hijacking by logging out of websites, enabling multi-factor authentication and being cautious of the links they click. 

Continue reading to learn more about session hijacking, how website owners can prevent session hijacking and how website visitors can stay protected against session hijacking. 

What is a session?

A session is an interaction you have with a website, usually from the time you log in to your account to the time you navigate away. A session ends when you log out and leave the site or you’re inactive on the site for a certain period (for example, you switch to a new tab for 20 minutes). After the session ends, you will need to log back into your account, which creates a new session.

How does session hijacking work?

Session hijacking is accomplished through various methods. The process, however, involves the following three main stages.  

1. Stealing the session ID

The cybercriminal obtains your session ID, typically through intercepting session cookies or tricking you into revealing it through phishing attempts.

2. Pretending to be you

Once the cybercriminal has the stolen session ID in hand, they can pose as you and gain access to your session. This is achieved by presenting the stolen session ID to the website or application, which may grant access to your session without further authentication.

3. Exploiting access

Having gained access to the session, the cybercriminal can access confidential information, modify settings or perform transactions and activities that you are authorized to do. This can lead to widespread security issues if you use Single Sign-On (SSO) because the cybercriminal can gain unauthorized access to multiple applications.

Common session hijacking techniques

Before learning how to prevent session hijacking, let’s discuss the techniques cybercriminals use to hijack sessions. Some of the most common and effective methods a hijacker uses are cross-site scripting, session sniffing, session fixation and malware. 

• Cross-site scripting (XSS): When cybercriminals inject malicious scripts into web pages to steal session cookies. 
• Session sniffing: A method that involves monitoring a network’s traffic for valid session tokens.  
• Session fixation: When a user is forced to use a session ID that a cybercriminal has already compromised. 
• Malware: Malicious software used to steal browser information, including session IDs.

How website admins can prevent session hijacking

As a website admin, here’s how you can prevent session hijacking.

Use HTTPS across the entire website

Make sure that your website uses HTTPS to encrypt data transmitted between your site and the users. This encryption helps protect sensitive information such as login details and session IDs from being intercepted by cybercriminals, thereby enhancing security. Additionally, set up HSTS (HTTP Strict Transport Security) on web servers to ensure that browsers always establish secure HTTPS connections, effectively blocking Man-in-the-Middle (MITM) attacks.

Strengthen session management

It’s important to generate session IDs using random values and set appropriate expiration periods for sessions. Issuing new session IDs after authentication helps prevent session fixation. Also, use features like “HttpOnly” and “Secure” on session cookies to reduce the risk of session ID theft through Cross-Site Scripting (XSS) attacks.

How website visitors can prevent session hijacking

Session hijacking isn’t only a problem for website admins – website visitors should also take precautions to prevent falling victim to it. As a website visitor, you can prevent session hijacking by following these tips. 

Always log out of websites when you are done

Logging out of websites after you are done is important because once you log out, the session ID is invalid and cannot be used maliciously.

Enable Multi-Factor Authentication (MFA) for every online account

MFA can prevent session hijacking because it adds an extra layer of security by requiring additional methods of authentication in addition to usernames and passwords. Many session hijacking attacks take advantage of stolen credentials; however, with MFA even if cybercriminals get your login credentials, they won’t be able to access your account without the second authentication requirement. 

Be cautious of the links you click

Before clicking on a link, make sure that it is safe to do so. Some links may look legitimate but instead of taking you to the website you’re looking for, they may direct you to a malicious phishing site that’s trying to get you to enter your password or install malware. As mentioned above, malware is a method used to hijack a session.

Avoid public WiFi

Public WiFi isn’t secure, and it’s easy for cybercriminals to hijack sessions through Man-in-the-Middle attacks. If possible, avoid public WiFi completely. Instead, opt for secure private networks and use a Virtual Private Network (VPN) to encrypt your traffic.

Keep yourself safe from session hijacking

Session hijacking is a serious cyber threat that can affect businesses and individuals. However, session hijacking can be prevented by taking the right steps ahead of time for both website admins and website visitors. Implementing simple security measures like HTTPS across your site and following strong session management practices are essential in mitigating the risk of session hijacking. Website visitors can do their part by logging out of sites, using MFA, being cautious of suspicious links and avoiding public WiFi. By being proactive, website owners and visitors can minimize the risk of session hijacking and have a secure online experience.