The OpenVPN project has addressed three significant vulnerabilities in OpenVPN version 2.6.11, released on June 21, 2024. These vulnerabilities, now disclosed in detail, pose risks ranging from unauthorized code execution to credential theft and unauthorized connection persistence. Organizations and individuals using OpenVPN are strongly advised to upgrade to version 2.6.11 or later to mitigate these security risks.
Vulnerabilities Identified
- CVE-2024-5594: Data Injection into Third-Party Executables
- Description: Improper sanitization of PUSH_REPLY messages allows attackers to inject arbitrary data into third-party executables or plugins.
- Impact:
- Code execution or denial-of-service conditions by a malicious OpenVPN peer.
- Severity: Critical (CVSS 9.1).
- Affected Systems: All platforms using OpenVPN prior to 2.6.11.
- CVE-2024-4877: Credential Theft via Interactive Service Pipe (Windows Only)
- Description: Exploits a weakness in the OpenVPN GUI’s interactive service pipe to steal user credentials. A malicious process with the SeImpersonatePrivilege can trick OpenVPN GUI into providing tokens, enabling full access to the user account.
- Impact:
- Credential theft and potential privilege escalation.
- Severity: High (CVSS 8.5).
- Affected Systems: Windows installations of OpenVPN prior to 2.6.11.
- CVE-2024-28882: Unauthorized Connection Persistence
- Description: Authenticated clients can maintain a connection to the server even after the server initiates a disconnect.
- Impact:
- Persistent unauthorized access to the server.
- Potential disruption of server operations.
- Severity: Medium (CVSS 6.4).
- Affected Systems: All platforms using OpenVPN prior to 2.6.11.
Affected Versions
- OpenVPN versions prior to 2.6.11.
Mitigation Steps
- Upgrade to OpenVPN 2.6.11 or Later:
- Download the latest version from the OpenVPN website.
- Apply Additional Security Measures:
- For Windows systems, limit access to processes with elevated privileges (e.g., SeImpersonatePrivilege) to mitigate CVE-2024-4877.
- Monitor server activity to detect and mitigate unauthorized connections stemming from CVE-2024-28882.
- Configuration Hardening:
- Review and sanitize configuration files to minimize potential exploitation vectors.
- Disable unused plugins and executables that could be targeted through CVE-2024-5594.
- Network Monitoring:
- Deploy network intrusion detection systems (NIDS) to monitor for unusual activity, such as unauthorized client persistence or unexpected credential usage.
Impact Analysis
These vulnerabilities present a range of risks, particularly for environments with high security requirements:
- CVE-2024-5594: Exploitation can lead to remote code execution or denial-of-service conditions, posing a significant threat to system availability and integrity.
- CVE-2024-4877: Credential theft on Windows systems could lead to privilege escalation and lateral movement within the network.
- CVE-2024-28882: Persistent unauthorized connections could disrupt server operations and compromise sensitive data.
Recommendations
- Update Immediately:
- Users of OpenVPN should upgrade to version 2.6.11 or later without delay.
- Enhance Access Controls:
- Restrict privileges for sensitive services and processes.
- Ensure robust access controls on Windows systems to limit exploitation opportunities.
- Long-Term Security Practices:
- Regularly audit OpenVPN deployments for signs of potential exploitation.
- Follow best practices for configuration management and secure deployment.
