CVE-2025-1025: Cockpit CMS File Upload Vulnerability

CVE-2025-1025 Overview

CVE-2025-1025 is an Arbitrary File Upload vulnerability affecting Cockpit CMS (cockpit-hq/cockpit) versions prior to 2.4.1. This vulnerability allows attackers to bypass the file upload filter by using alternative PHP file extensions, potentially enabling remote code execution on vulnerable systems.

Critical Impact

Attackers can bypass upload restrictions to upload malicious PHP files using alternative extensions like .phar and .phtml, potentially leading to complete server compromise through remote code execution.

Affected Products

• Cockpit CMS (cockpit-hq/cockpit) versions before 2.4.1

Discovery Timeline

• February 5, 2025 - CVE-2025-1025 published to NVD
• February 5, 2025 - Last updated in NVD database

Technical Details for CVE-2025-1025

Vulnerability Analysis

This Arbitrary File Upload vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) exists in Cockpit CMS's file upload functionality. The application implements a security filter to prevent uploading PHP files; however, the filter only blocks files with the .php extension. Attackers can trivially bypass this restriction by using alternative PHP-executable extensions such as .phar and .phtml, which are typically processed by web servers with PHP configurations.

The vulnerability affects two key modules: the Assets manager (modules/Assets/bootstrap.php) and the Finder controller (modules/Finder/Controller/Finder.php). Both components contained inadequate extension validation that only checked for the .php extension, leaving other PHP-executable extensions unblocked.

Root Cause

The root cause is an incomplete denylist implementation in the file extension validation logic. The original code only checked if the file extension equals 'php', failing to account for other extensions that PHP handlers process. This is a classic case of insufficient input validation where security relies on a blocklist approach that doesn't cover all dangerous file types.

Attack Vector

An attacker with access to the file upload functionality can exploit this vulnerability by:

1. Preparing a malicious PHP payload (e.g., a web shell)
2. Renaming the file to use an alternative PHP extension (.phar or .phtml)
3. Uploading the file through the Assets manager or Finder module
4. Accessing the uploaded file via web browser to execute arbitrary PHP code

This is a network-based attack requiring no user interaction. While some Cockpit installations may require authentication to access upload features, the vulnerability allows authenticated users to escalate their access to arbitrary code execution on the server.

// Vulnerable code - only checked for .php extension
if ($_isAllowed && pathinfo($_file, PATHINFO_EXTENSION) === 'php') {
    $_isAllowed = false;
}

// Patched code - now blocks php, phar, and phtml extensions
if ($_isAllowed && in_array(strtolower(pathinfo($_file, PATHINFO_EXTENSION)), ['php', 'phar', 'phtml'])) {
    $_isAllowed = false;
}

Source: GitHub Commit Update

Detection Methods for CVE-2025-1025

Indicators of Compromise

• Presence of .phar or .phtml files in Cockpit's upload directories
• Unexpected PHP files in the assets or storage directories
• Web server logs showing requests to unusual file extensions in upload paths
• Signs of web shell activity or unauthorized command execution

Detection Strategies

• Monitor file upload events for files with extensions .phar, .phtml, or other PHP-executable types
• Implement file integrity monitoring on Cockpit's upload and storage directories
• Review web server access logs for requests to files with suspicious extensions
• Deploy web application firewall (WAF) rules to detect malicious file upload attempts

Monitoring Recommendations

• Enable detailed logging for all file upload activities in Cockpit CMS
• Set up alerts for any newly created files with PHP-executable extensions in upload directories
• Monitor for outbound connections from the web server that may indicate web shell activity
• Regularly scan uploaded content for malicious PHP code patterns

How to Mitigate CVE-2025-1025

Immediate Actions Required

• Upgrade Cockpit CMS to version 2.4.1 or later immediately
• Audit existing upload directories for any suspicious .phar, .phtml, or other PHP-executable files
• Review web server access logs for potential exploitation attempts
• Consider temporarily disabling file upload functionality until the patch is applied

Patch Information

Cockpit-HQ has released security patches that extend the file extension blocklist to include php, phar, and phtml extensions. The patches also normalize extension comparison to lowercase to prevent case-based bypass attempts.

The security fixes are available in the following commits:

• Initial patch for Assets bootstrap.php
• Extended patch covering additional modules

For detailed vulnerability information, see the Snyk Vulnerability Report.

Workarounds

• Configure web server to disable PHP execution in upload directories using .htaccess or server configuration
• Implement additional file validation at the web server level to block dangerous extensions
• Restrict access to file upload functionality to trusted administrators only
• Use a web application firewall to filter malicious file upload requests

# Apache configuration to prevent PHP execution in uploads directory
# Add to .htaccess or VirtualHost configuration
<Directory "/path/to/cockpit/storage/uploads">
    php_admin_flag engine off
    RemoveHandler .php .phar .phtml
    <FilesMatch "\.(php|phar|phtml)$">
        Require all denied
    </FilesMatch>
</Directory>