1. Introduction
The cPanel cpsrvd.pl user parameter is vulnerable to a cross-site scripting (XSS) attack. This means an attacker could inject malicious scripts into a user’s browser when they visit the affected web server, potentially stealing cookies or performing actions as that user. Systems running vulnerable versions of cPanel are at risk. A successful exploit can lead to loss of confidentiality, integrity and availability depending on the privileges of the compromised user.
2. Technical Explanation
The vulnerability occurs because cPanel fails to properly sanitize user input provided to the ‘user’ parameter of the login page within the cpsrvd.pl script. This allows an attacker to inject arbitrary HTML and JavaScript code, which is then executed in the context of the victim’s browser. The attack is remote exploitable, meaning it can be carried out over a network connection without requiring local access to the server.
- Root cause: Insufficient input validation on the ‘user’ parameter within cpsrvd.pl.
- Exploit mechanism: An attacker crafts a malicious URL containing JavaScript code in the ‘user’ parameter, then tricks a user into visiting that URL. For example:
http://example.com/cpsrvd.pl?user=. - Scope: cPanel versions affected are not explicitly specified but CVE-2005-2021 is associated with this vulnerability.
3. Detection and Assessment
To confirm if a system is vulnerable, first check the installed version of cPanel. A thorough assessment involves attempting to inject a simple XSS payload.
- Quick checks: Use the following command to determine your cPanel version:
cpanel --version - Scanning: Nessus plugin ID 30869 can detect this vulnerability, but results should be verified manually.
- Logs and evidence: Examine web server logs for suspicious requests containing JavaScript code in the ‘user’ parameter of cpsrvd.pl. Look for patterns like `