CVE-2025-25291
Remediation/Mitigation Strategy for CVE-2025-25291: Ruby-SAML Authentication Bypass
Vulnerability: Authentication Bypass in ruby-saml due to Parser Differential (Signature Wrapping Attack)
Description:
The ruby-saml library, which provides SAML SSO functionality for Ruby applications, contains a vulnerability (CVE-2025-25291) related to how it parses XML documents. Different XML parsers (specifically ReXML and Nokogiri) can interpret the same XML input in significantly different ways, resulting in distinct document structures. This discrepancy allows attackers to craft malicious SAML responses that exploit this parsing differential. A successful attack can result in a Signature Wrapping attack, where the signature is effectively moved or altered to validate an untrusted or modified SAML response. This bypasses authentication and allows unauthorized access to protected resources.
Severity:
- CVSS Score: 8.8 (High)
- Impact: Allows unauthorized access to applications relying on SAML authentication provided by ruby-saml. An attacker can potentially impersonate any user within the system.
- Confidentiality Impact: High - Unauthorized access to sensitive data.
- Integrity Impact: High - Data could be modified by an unauthorized user.
- Availability Impact: High - The system could be taken offline, depending on the level of access gained.
Known Exploit:
Signature wrapping attacks are a well-known technique for exploiting vulnerabilities in XML processing. While specific exploit code isn’t explicitly mentioned in the advisory, the description makes it clear that carefully crafted SAML responses can be used to bypass signature validation. The potential for a successful exploit is high, given the known nature of signature wrapping attacks.
Remediation/Mitigation Strategy:
Immediate Upgrade: The primary and most effective solution is to upgrade the
ruby-samlgem to the patched versions 1.12.4 or 1.18.0 or later. These versions contain the fix for the parser differential vulnerability.- Using Bundler, update your Gemfile:
gem ‘ruby-saml’, ‘
> 1.12.4’ #Or gem ‘ruby-saml’, ‘> 1.18.0’ * Runbundle update ruby-samlto install the new version. - Verify the version:
bundle list ruby-saml - If you are not using bundler, use the following command: gem update ruby-saml
- Using Bundler, update your Gemfile:
gem ‘ruby-saml’, ‘
Verification and Testing: After upgrading, thoroughly test your SAML integration to ensure that authentication is functioning correctly and that the vulnerability has been resolved. Pay particular attention to testing with various SAML responses, including potentially malformed or crafted messages.
Code Review (If Applicable): If you have custom code that interacts with the ruby-saml library, review the code to ensure that you are not inadvertently introducing vulnerabilities through custom SAML response handling. Consider using a secure coding checklist focusing on XML processing best practices.
Web Application Firewall (WAF) Rules (Temporary Mitigation): As a temporary mitigation measure while the upgrade is being implemented and tested, consider deploying WAF rules to filter out suspicious SAML requests that might be indicative of signature wrapping attacks. This requires a deep understanding of SAML and signature wrapping techniques. Note: This is not a substitute for upgrading the ruby-saml library. This should be used as an extra layer of protection.
- The difficulty in implementing good WAF rules lies in identifying malicious payloads without impacting legitimate traffic. Common methods include:
- XML Schema Validation: Enforce strict adherence to the SAML XML schema to reject responses that deviate from the expected structure.
- Signature Location Enforcement: WAF can be configured to analyze the XML and ensure the signature is within the expected location of the SAML Response.
- The difficulty in implementing good WAF rules lies in identifying malicious payloads without impacting legitimate traffic. Common methods include:
Dependency Scanning: Implement regular dependency scanning using tools like Bundler Audit, Dependabot, or other vulnerability scanning solutions to identify and address security vulnerabilities in your Ruby dependencies proactively.
Monitor and Log: Increase monitoring and logging of SAML authentication events to detect any suspicious activity. Log relevant information such as the SAML response, the user attempting authentication, and the timestamp.
Communication: Communicate the vulnerability and the remediation steps to relevant stakeholders, including developers, security teams, and system administrators.
Timeline:
- Immediate: Upgrade the
ruby-samlgem in all environments (development, staging, and production). Implement WAF rules (if applicable) as a temporary mitigation. - Within 1 Week: Conduct thorough testing of the upgraded SAML integration. Complete code review and dependency scanning.
- Ongoing: Maintain dependency scanning and monitoring of SAML authentication events.
Responsible Parties:
- Security Team: Vulnerability assessment, WAF rule configuration, testing, and monitoring.
- Development Team: Upgrading the
ruby-samlgem, code review, and testing. - Operations Team: Deployment of the upgraded gem and monitoring of system logs.
Assigner
- GitHub, Inc. [email protected]
Date
- Published Date: 2025-03-12 20:16:12
- Updated Date: 2025-03-12 22:15:35