What Is Session Hijacking

What Is Session Hijacking? How Does It Work?

Due to the COVID-19 pandemic, many people are now migrating to teleconferencing services to work [1]. However, this presents both benefits and obstacles that companies have not taken into account. This has led to concerns about online security as the pandemic has advanced. One of the major network security concerns is session hijacking, also referred to as cookie hijacking, which is a web attack used by hackers to exploit active web sessions.

It is important that organizations address this because sessions are a vital part of internet communication and it is usually web-based. Furthermore, a web server needs to have authentication because every user communication through the website uses multiple TCP/IP channels.

In this blog, you will learn about browser sessions and cookie hijacking, and how security experts can prevent them.

What Is A Session?

HTTP is stateless, which means that each request will be carried out independently without any knowledge of the previously executed requests. This means you will need to enter your username and password again for any page you viewed. Thus, developers need to create a way for you to track the state between multiple connections from the same user instead of asking them to reauthenticate after each click in a web application.

This is what led to sessions. A session is known as the period of communication between two computer systems. This means a session will be created on the server once you log in to an application. This helps maintain the state and will be referenced whenever you make any future requests.

What Is Session Hijacking?

Session hijacking, also known as cookie side-jacking, is a process where cybercriminals take over an active TCP/IP communication session without the user’s permission [2]. If a cookie hijacking is successful, the attacker will use the compromised user’s identity to enjoy the same access to resources as the compromised user. Some of the common impacts of session hijacking are information theft, identity theft, and stealing sensitive data.

What Can Attackers Do After a Successful Session Hijacking?

Once a cookie side-jacking is successful, attackers can perform actions that the original user is authorized to do in an active session [3]. Session hijacking depends on the target application as cyber attackers can encrypt valuable data, steal the client’s data from computer systems, transfer money from the user’s bank account, etc.

The major risk of session hijacking for larger organizations is that hackers can use cookies to identify authenticated users in a single sign-on system (SSO). This means that with a successful session hijack, attackers can gain SSO access to numerous web applications like financial systems and customer records that contain valuable intellectual property.

Difference Between Session Hijacking and Session Spoofing

Although session hijacking and session spoofing are closely related, they differ in the timing of the attack. Session hijacking is usually done against a user who is currently logged in and authenticated. This can then cause the targeted application to behave unpredictably or crash from the victim’s perspective.

However, during session spoofing, attackers use counterfeit or stolen session tokens to initiate a new browser session and then impersonate the original user, who may not be aware of the attack.

How Does Session Hijacking Work?

A session side jacking occurs when a cybercriminal exploits a compromised active session by hijacking or stealing the session ID to maintain a session. Another way is by predicting an active session to gain unauthorized access to the information remotely without detection. Some of the ways a session cookie or token can be manipulated are:

Session Sniffing

This process can be used to hijack a session when the communication between the web server and the user is not encrypted. This means the session ID is sent in plain text. Hence, an intruder monitoring the network can easily get the session key and use it to be automatically authenticated to the webserver. Ethical hacking tools like Wireshark and Kismet can capture sensitive data packets like session ID from the network during network monitoring.

Cross-Site Scripting (XSS)

According to OWASP, cross-site scripting is one of the top ten web application security risks. This means a server can be vulnerable to cross-site scripting exploits, and it enables an attacker to execute malicious code from the user’s side to gather session information. A cybercriminal can target the victim’s browser session and web application to send a scripted JavaScript link, and once a user opens it, the malicious code starts running.

Session Hijacking Countermeasures

Here are some ways you can prevent session hijacking:

  • By generating long and random session cookies from web servers to reduce the chances of guessing or predicting a session cookie.
  • Using end-to-end encryption between the user’s browser sessions and web application using a secure SSL or HTTP to prevent unauthorized access to the session ID. You can also use personal VPN solution tools to encrypt everything.
  • You can implement an automatic log off when a session is not in use, and the client can then be required to reauthenticate using a different session ID. Furthermore, an organization can reduce the amount of time a session cookie is being exposed in a network by directing the server to delete a session cookie from a client’s computer.
  • Organizations can use session ID monitors to monitor if session IDs are being used and then implement utilities like Blacksheep to send fake session IDs to the network and watch when an intruder tries to use the session ID.

Learn How to Shield Your Network from Session Hijacking

Session hijacking is among the top modern cyberthreats to both applications and networks. This is because hackers can take over the network, service, or web session to gain unauthorized access to the system & data and attack an organization. This is why security professionals need to understand a hacker’s attack patterns to implement adequate preventive measures to mitigate the risk.

EC-Council CodeRed’s “Session Hijacking Course” is the perfect place to start learning as it will bring you up to speed on everything there is to know about session hijacking. By the end of this course, you will learn about the various vulnerabilities in web applications, wireless protocols, and network protocols, and how hackers exploit them. You will also get a hands-on experience of using built-in Linux and Windows tools and third-party proxy solutions to detect and exploit vulnerabilities in a network.

Visit CodeRed today to learn more: https://codered.eccouncil.org/


Does SSL prevent session hijacking?
SSL helps to encrypt the data that is transferred constantly between the user’s browser and web servers [4]. This means that even if a hacker manages to steal data, he/she cannot read it.


  1. https://www.gb-advisors.com/session-hijacking-what-is-it-and-how-to-prevent-illegal-access-to-your-data/
  2. https://www.greycampus.com/opencampus/ethical-hacking/session-hijacking-and-its-types
  3. https://www.netsparker.com/blog/web-security/session-hijacking/
  4. https://securityboulevard.com/2020/01/how-to-prevent-cookie-stealing-and-hijacking-sessions-easiest-guide/
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