Executive Summary

CVE-2016-20053 is a Cross-Site Request Forgery (CSRF) vulnerability in Redaxo CMS version 5.2 and earlier. It allows unauthenticated attackers to create administrative user accounts by tricking authenticated administrators into visiting malicious web pages.

Attackers craft malicious HTML forms targeting the users endpoint with hidden fields containing admin credentials and account parameters. When an authenticated administrator visits such a malicious page, the form can be submitted (automatically or manually), resulting in the creation of new administrator accounts without the administrator's consent or knowledge.

This vulnerability exploits the lack of proper CSRF protections in Redaxo CMS 5.2, allowing unauthorized privilege escalation through forged requests.

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Impact Analysis

This vulnerability can have serious security impacts by allowing attackers to gain administrative access to the Redaxo CMS without authorization.

• Attackers can add new administrator accounts with full privileges.
• Unauthorized administrative users can modify site content, change configurations, or perform other privileged actions.
• The attack requires no privileges or user interaction beyond the administrator visiting a malicious page.

Overall, this can lead to a complete compromise of the CMS, loss of control over the website, and potential further exploitation.

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Detection Guidance

This vulnerability can be detected by monitoring for unauthorized creation of administrative user accounts in Redaxo CMS version 5.2 or earlier. Since the exploit involves a POST request to the users management endpoint (index.php?page=users/users) with specific parameters, network or web server logs can be inspected for suspicious POST requests containing parameters like userlogin, useradmin=1, userstatus=1, and userpsw with a SHA-1 hash.

Suggested commands to detect potential exploitation attempts include searching web server logs for POST requests to the users endpoint with admin account creation parameters. For example, using grep on Apache or Nginx logs:

• grep 'POST /index.php?page=users/users' /var/log/apache2/access.log
• grep -i 'useradmin=1' /var/log/apache2/access.log
• grep -i 'userpsw=7c4a8d09ca3762af61e59520943dc26494f8941b' /var/log/apache2/access.log

Additionally, monitoring for new administrative users created without proper authorization in the CMS backend or database can help detect exploitation.

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Mitigation Strategies

To mitigate this vulnerability immediately, it is recommended to apply CSRF protections on the users endpoint in Redaxo CMS 5.2 or upgrade to a version where this vulnerability is fixed.

As an immediate workaround, restrict access to the user management page to trusted administrators only, and avoid visiting untrusted or suspicious web pages while logged in as an administrator.

Additionally, monitor and audit administrative user accounts regularly to detect any unauthorized additions.

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Compliance Impact

The vulnerability allows unauthenticated attackers to create administrative user accounts by exploiting a CSRF flaw in Redaxo CMS 5.2. This unauthorized privilege escalation can lead to unauthorized access and control over sensitive data and system functions.

Such unauthorized administrative access could potentially violate common security requirements in standards and regulations like GDPR and HIPAA, which mandate strict access controls and protection of personal and sensitive data.

However, the provided information does not explicitly describe the direct impact on compliance with these regulations.

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