CVE-2003-0960 in OpenCA
Summary
by MITRE
OpenCA before 0.9.1.4 does not use the correct certificate in a chain to check the serial, which could cause OpenCA to accept revoked or expired certificates.
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability identified as CVE-2003-0960 affects OpenCA versions prior to 0.9.1.4 and represents a critical flaw in certificate validation mechanisms within the certificate authority software. This issue stems from improper certificate chain validation where the system fails to correctly utilize the certificate at the appropriate position within the certificate chain when performing serial number verification. The flaw creates a significant security gap that undermines the fundamental trust model of public key infrastructure by allowing malicious actors to potentially bypass certificate revocation checks. This vulnerability specifically impacts the certificate validation process where the software should verify certificate serial numbers against a revocation list or expiration status but instead uses incorrect certificate references in the chain, leading to potential acceptance of compromised certificates.
The technical implementation of this vulnerability resides in the certificate chain validation logic where OpenCA's certificate processing engine incorrectly identifies which certificate within the chain should be used for serial number verification. This flaw typically manifests when the software processes certificate chains containing intermediate certificates, where the validation routine fails to properly traverse the chain and instead relies on a certificate that may not represent the actual certificate being validated. The issue falls under the CWE-295 category of "Improper Certificate Validation" and demonstrates poor implementation of certificate chain validation procedures that should adhere to established PKI standards. When a certificate chain is processed, the system should validate each certificate in the chain against the appropriate trust anchor and verify the serial numbers against known revocation lists, but the flawed implementation causes this verification to fail.
The operational impact of this vulnerability is severe as it directly compromises the integrity of certificate validation within OpenCA systems. An attacker could potentially exploit this flaw to present revoked or expired certificates that would be incorrectly accepted by the system, effectively bypassing the certificate revocation mechanism. This could lead to unauthorized access to systems, man-in-the-middle attacks, or the acceptance of fraudulent certificates that appear valid to the vulnerable system. The vulnerability particularly affects environments where OpenCA serves as a certificate authority or where certificate validation is critical for system security, potentially allowing attackers to establish trust in compromised certificates that should have been rejected based on their revocation status or expiration dates. According to ATT&CK framework, this vulnerability maps to T1552.001 (Credentials in Files) and T1552.006 (Credentials in Registry) as it enables attackers to potentially manipulate certificate-based authentication systems.
Mitigation strategies for CVE-2003-0960 primarily involve upgrading to OpenCA version 0.9.1.4 or later where the certificate chain validation has been corrected to properly utilize the correct certificate for serial number verification. Organizations should also implement additional monitoring of certificate validation logs to detect potential exploitation attempts and establish robust certificate lifecycle management procedures that include regular certificate audits. Security teams should verify that certificate chains are properly validated and that the system correctly traverses certificate chains to ensure that serial number verification occurs against the appropriate certificates. The fix implemented in version 0.9.1.4 addresses the core validation logic to ensure proper certificate chain traversal and serial number verification against the correct certificates in the chain. Additionally, organizations should consider implementing certificate pinning mechanisms and enhanced monitoring to detect any anomalous certificate validation behaviors that might indicate exploitation attempts against this vulnerability.