Exploring Session Hijacking: How Attackers Compromise Web Sessions

Session hijacking is a critical security vulnerability that can lead to unauthorized access to user accounts, data theft, and much more. By gaining control over a user’s session, attackers can impersonate the victim, effectively taking over their interactions with a web application. In this post, we’ll delve into what session hijacking is, how it works, and demonstrate a real-world example.

Session Hijacking

Session hijacking occurs when an attacker gains unauthorized control over a legitimate user’s session on a web application. When a user logs in, the server generates a session token (usually stored in a cookie), which maintains the user’s state across various interactions. If an attacker can obtain this session token, they can impersonate the victim and gain full access to the victim’s account without needing to know their credentials.

Session Tokens:
These tokens are used to maintain a user’s authenticated session. Typically stored as cookies, URL parameters, or in HTTP headers, these tokens are vulnerable if not properly secured.Common Attack Techniques:
Attackers have several methods to hijack sessions, including:Packet Sniffing: Capturing network traffic on unsecured connections to steal session tokens.Cross-Site Scripting (XSS): Exploiting XSS vulnerabilities to execute malicious scripts that steal session cookies.Man-in-the-Middle (MITM) Attacks: Intercepting communication between the client and server to steal or manipulate session tokens.

This is an example of a session hijacking vulnerability on the domain https://www.ceo.scholarfundwa.org.

Step-by-Step Exploitation

create an Account:
First, quickly create an account on https://www.ceo.scholarfundwa.org and log in to the application.Install Cookie Editor:
Download the Cookie Editor browser extension to manipulate session cookies:
https://cookie-editor.com/#download.Session Hijacking Process:Open the web application in one browser and log in.Copy all session cookies from the browser using the Cookie Editor extension and save them in JSON format.In a second browser, delete all existing cookies for the site, and then paste the saved cookies from the first browser.Refresh the page in the second browser — you will be logged in without ever using credentials again. This proves that session hijacking via cookie manipulation is possible.Real-Life Example:
In real-world attacks, session hijacking can be carried out by phishing campaigns that trick users into sharing their session cookies. Once attackers have the session token, they can log in, change passwords, and take over the account.

The potential consequences of a session hijacking attack include:

Unauthorized Access:
Attackers can impersonate the victim and perform actions on their behalf, such as accessing sensitive information, initiating transactions, or changing account settings.Data Theft:
Personal details, financial information, and other sensitive data can be stolen during a session hijacking attack.Reputation Damage:
If a company or service suffers from session hijacking, it can face a loss of user trust and potential legal consequences, impacting its reputation.

Mitigating the risks of session hijacking requires a combination of security measures to protect session tokens and prevent unauthorized access.

Use Secure Cookies:
Always set session cookies to be Secure (to ensure they are only transmitted over HTTPS) and HttpOnly (to prevent JavaScript from accessing them).Implement Session Expiration:
Regularly expire sessions and require re-authentication after a specified period, especially before performing sensitive actions like changing passwords or transferring funds.Use CSRF Tokens:
Implement Cross-Site Request Forgery (CSRF) tokens to validate that user requests are legitimate and coming from an authenticated session.Always Use HTTPS:
Encrypt all communication between the user and the server using HTTPS to prevent session tokens from being intercepted via packet sniffing or MITM attacks.

Session hijacking remains a persistent and dangerous threat to web applications, allowing attackers to bypass authentication and gain unauthorized access to sensitive data. By understanding the attack vectors and implementing proper security measures — such as secure cookie handling, session expiration, and HTTPS — organizations can significantly reduce their exposure to this vulnerability.

A special thanks to https://www.ceo.scholarfundwa.org for their role in identifying and resolving this session hijacking vulnerability. This discovery highlights the importance of secure session management to prevent unauthorized access and data breaches.

When referencing this work, please credit Mrutunjaya Senapati. Thank you!