EUVD-2025-25168

Comprehensive Technical Analysis of EUVD-2025-25168

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-25168 affects Plesk Obsidian 18.0.70, specifically within the _isAdminPasswordValid function. The issue arises from the use of a loose comparison operator (==) instead of a strict comparison operator (===). This allows an attacker to bypass authentication by exploiting the way PHP handles type juggling.

Severity Evaluation:

• Base Score: 9.8 (Critical)
• Base Score Version: CVSS 3.1
• Base Score Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

The high base score indicates a critical vulnerability due to the ease of exploitation (low complexity) and the severe impact on confidentiality, integrity, and availability.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Remote Exploitation: An attacker can exploit this vulnerability over the network without requiring any user interaction or privileges.
• Authentication Bypass: By crafting a specific password string that evaluates to 0.0 (e.g., 0e0), an attacker can bypass the admin login mechanism.

Exploitation Methods:

• Password Guessing: An attacker can attempt to log in using known admin usernames and crafted passwords like 0e0, 0e123, etc.
• Automated Scripts: Attackers can use automated scripts to brute-force the login mechanism with various crafted passwords.

3. Affected Systems and Software Versions

Affected Software:

• Plesk Obsidian 18.0.70

Affected Systems:

• Any system running Plesk Obsidian 18.0.70, including web servers, hosting control panels, and other environments where Plesk is used for management.

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Patching: Apply the latest security patch provided by Plesk to address this vulnerability.
• Code Review: Ensure that all password comparisons use strict comparison operators (===) to avoid type juggling issues.

Long-Term Mitigation:

• Regular Updates: Keep Plesk and all related software up to date with the latest security patches.
• Security Audits: Conduct regular security audits and code reviews to identify and mitigate similar vulnerabilities.
• Monitoring: Implement monitoring and alerting for unusual login attempts and failed authentication events.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to organizations using Plesk Obsidian 18.0.70, particularly those in the European Union. Given the critical nature of the vulnerability, it could lead to unauthorized access to administrative interfaces, data breaches, and potential disruption of services. This underscores the importance of timely patching and proactive security measures to protect against such threats.

6. Technical Details for Security Professionals

Vulnerable Code:

if ($_POST['password'] == $storedPassword) {
    // Authenticate user
}

Fixed Code:

if ($_POST['password'] === $storedPassword) {
    // Authenticate user
}

Exploitation Example: An attacker can exploit this vulnerability by sending a POST request with a crafted password:

POST /admin/plib/LoginManager.php HTTP/1.1
Host: example.com
Content-Type: application/x-www-form-urlencoded

username=admin&password=0e0

Detection:

• Log Analysis: Look for unusual login attempts with passwords like 0e0, 0e123, etc.
• Intrusion Detection Systems (IDS): Configure IDS to detect and alert on suspicious login attempts.

Prevention:

• Input Validation: Ensure that all input is properly validated and sanitized.
• Strong Authentication: Implement multi-factor authentication (MFA) to add an additional layer of security.

Conclusion: The vulnerability in Plesk Obsidian 18.0.70 is critical and requires immediate attention. Organizations should prioritize patching and implementing the recommended mitigation strategies to protect against potential exploitation. Regular security audits and proactive measures are essential to maintain a robust cybersecurity posture.

References:

• Plesk Obsidian 18.0.70 Announcement
• Plesk Support Article on CVE-2025-54336