Critical Session Management Vulnerability Leading to Account Hijacking

During a routine security assessment, I discovered a critical vulnerability in a web application that allowed unauthorized access to user accounts. The root cause was improper session management — specifically, the session files were publicly accessible. In this writeup, I detail the discovery process, steps taken to exploit the vulnerability for remediation — all while keeping the target’s identity and domain confidential.

The vulnerability arises because the /storage/sessions/ directory on the target website is publicly accessible. This misconfiguration exposes session files, which can be exploited to hijack user sessions and gain unauthorized access to sensitive information.

note: add this directory /storage/sessions/ for your wordlist

The issue stems from weak session management. By making the session storage directory publicly accessible, an attacker can download and inspect session files to identify valid session identifiers that allow impersonation of legitimate users.

First Impressions:
I started by noticing that the employee-facing domain only displayed a login page

2. Directory Reconnaissance:
I then used Dirsearch to scan for available directories

command :

dirsearch -u example.com -r

3. The Storage Discovery:
My scan revealed a directory named storage that returned a 200 OK status. This was my first clue that something interesting was behind the scenes.

4. Uncovering the Sessions:
Upon exploring the storage directory, I found three subdirectories. One of them was named sessions

5. Examining the Session Files:

Inside the sessions directory, I discovered multiple files with names following the pattern:

yc_sessionFUZZ

6. Cookie Connection:
I noticed that the session cookie on the site started with:

yc_session=FUZZOkey..🙄

7. Exploitation — Changing the Cookie Value:
I then replaced my cookie’s value with the FUZZ value extracted from one of the session files.

8. The Finale:
guess what? I was able to access an employee account without a password.

This vulnerability is critical due to the following potential impacts:

Account Hijacking: An attacker can gain full control of user accounts using the exposed session identifiers.Data Exposure: Unauthorized access may lead to the disclosure of sensitive user and employee data.Reputation & Legal Ramifications: Such breaches can significantly damage the affected organization’s reputation and may lead to legal consequences.

This vulnerability highlights the critical importance of robust session management and secure configuration in web applications. Responsible disclosure and collaboration between security researchers and development teams are essential to maintain a secure online environment.