: Ensure sensitive files like /etc/passwd and /etc/shadow are not directly accessible through web applications. Implement proper access controls and consider additional security measures like Web Application Firewalls (WAFs).
Even without passwords, it is a file for path traversal vulnerabilities. -page-....-2F-2F....-2F-2F....-2F-2Fetc-2Fpasswd
On Linux and Unix-based systems, the /etc/passwd file is a goldmine for initial reconnaissance. It contains a list of every user on the system, their user IDs, and their home directory paths. While modern systems store actual passwords in a separate "shadow" file, knowing the usernames is the first step for an attacker to launch a brute-force or credential-stuffing attack. 3. How the Vulnerability Happens : Ensure sensitive files like /etc/passwd and /etc/shadow
: A user requests a profile page: view?page=home.php . The server looks in /var/www/html/pages/home.php . On Linux and Unix-based systems, the /etc/passwd file
: This is a slightly modified version of ../ , the "parent directory" command. The -2F-2F is URL encoding for the forward slash / . Attackers use encoding to bypass simple security filters that look for the literal ../ string.
Attackers use sequences like ../ to move up directories and access files outside the web root.
In a vulnerable web application, an attacker might use sequences like (often URL-encoded as