CVE-2024-0567 Overview
A vulnerability was discovered in GnuTLS affecting certificate chain validation when using distributed trust models. The flaw specifically impacts the cockpit-certificate-ensure validation process, where legitimate certificate chains with distributed trust are incorrectly rejected. This improper cryptographic signature verification (CWE-347) allows an unauthenticated, remote attacker to initiate a denial of service attack against affected systems.
Critical Impact
Remote attackers can exploit this certificate validation flaw to cause denial of service conditions on systems relying on GnuTLS for TLS/SSL certificate chain verification, affecting critical server management tools like Cockpit.
Affected Products
- GNU GnuTLS (multiple versions)
- Fedora 38 and 39
- NetApp Active IQ Unified Manager for VMware vSphere
- Debian Linux 11.0
Discovery Timeline
- 2024-01-16 - CVE-2024-0567 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2024-0567
Vulnerability Analysis
The vulnerability resides in GnuTLS's certificate chain validation logic, specifically affecting how the library processes certificate chains that utilize distributed trust anchors. When a certificate chain relies on trust distributed across multiple trust anchors or intermediate certificates, GnuTLS improperly rejects these otherwise valid chains. This behavior is triggered during the cockpit-certificate-ensure validation process, which is commonly used by the Cockpit web-based server management interface.
The flaw stems from improper verification of cryptographic signatures (CWE-347), where the validation algorithm fails to correctly traverse and verify trust paths in distributed trust scenarios. This results in legitimate TLS connections being terminated, effectively creating a denial of service condition.
Root Cause
The root cause lies in GnuTLS's certificate verification implementation, which does not properly handle certificate chains where trust is established through multiple independent trust anchors. The cockpit-certificate-ensure component relies on this validation, and when it encounters such chains, the verification fails incorrectly, causing service disruption rather than successful authentication.
Attack Vector
The vulnerability can be exploited remotely over the network without requiring authentication or user interaction. An attacker can craft or present certificate chains with distributed trust configurations to trigger the validation failure. Since the attack vector is network-based and requires no privileges, any system exposing GnuTLS-based TLS services (particularly Cockpit) is potentially vulnerable.
The attack flow involves presenting a certificate chain that would normally be valid but uses distributed trust anchors. When GnuTLS attempts to validate this chain, the improper verification logic rejects it, causing the TLS handshake to fail and denying service to legitimate users.
Detection Methods for CVE-2024-0567
Indicators of Compromise
- Unexpected TLS/SSL connection failures in Cockpit or GnuTLS-dependent services
- Elevated certificate validation errors in system logs referencing distributed trust chains
- Service availability degradation for web-based management interfaces
- Repeated authentication failures in applications using GnuTLS for certificate validation
Detection Strategies
- Monitor GnuTLS and Cockpit logs for certificate chain validation failures
- Implement alerting on abnormal rates of TLS handshake failures
- Review system authentication logs for patterns indicating certificate rejection issues
- Deploy network monitoring to detect unusual certificate presentation patterns
Monitoring Recommendations
- Enable verbose logging for GnuTLS certificate validation processes
- Configure SIEM rules to correlate TLS failures with potential DoS patterns
- Monitor service availability metrics for Cockpit and other GnuTLS-dependent applications
- Track system resource utilization during certificate validation operations
How to Mitigate CVE-2024-0567
Immediate Actions Required
- Update GnuTLS to the latest patched version provided by your distribution
- Apply vendor-specific security patches from Red Hat, Fedora, Debian, or NetApp
- Review and validate certificate chain configurations for distributed trust scenarios
- Consider implementing network-level rate limiting for TLS connections
Patch Information
Multiple vendors have released security advisories and patches addressing this vulnerability:
- Red Hat Security Advisory RHSA-2024:0533 - Initial patch release
- Red Hat Security Advisory RHSA-2024:1082 - Additional fixes
- Red Hat Security Advisory RHSA-2024:1383 - Extended platform coverage
- Red Hat Security Advisory RHSA-2024:2094 - Comprehensive update
- NetApp Security Advisory ntap-20240202-0011 - NetApp product updates
- Fedora package updates available for Fedora 38 and 39
For technical details about the vulnerability, refer to the GitLab GnuTLS Issue #1521.
Workarounds
- Temporarily avoid certificate chains with distributed trust configurations where possible
- Implement alternative TLS libraries for critical services if patches cannot be applied immediately
- Use certificate chain configurations with single trust anchors until patching is complete
- Consider network segmentation to limit exposure of vulnerable services
# Check installed GnuTLS version on RHEL/Fedora systems
rpm -qa | grep gnutls
# Update GnuTLS on RHEL/CentOS systems
sudo yum update gnutls
# Update GnuTLS on Fedora systems
sudo dnf update gnutls
# Update GnuTLS on Debian systems
sudo apt update && sudo apt upgrade libgnutls30
# Restart Cockpit service after patching
sudo systemctl restart cockpit
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
