CVE-2007-4994 in Certificate Server
Summary
by MITRE
Certificate Server 7.2 in Red Hat Certificate System (RHCS) does not properly handle new revocations that occur while a Certificate Revocation List (CRL) is being generated, which might prevent certain revoked certificates from appearing on the CRL quickly and allow users with revoked certificates to bypass the intended CRL.
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Analysis
by VulDB Data Team • 02/12/2017
The vulnerability identified as CVE-2007-4994 affects Red Hat Certificate System version 7.2 Certificate Server component, representing a significant weakness in the certificate lifecycle management process. This issue stems from improper handling of certificate revocation events during the active generation of Certificate Revocation Lists, creating a temporal window where certificate status updates may not be immediately reflected in published CRLs. The flaw fundamentally compromises the integrity of the certificate validation mechanism by allowing revoked certificates to remain undetected in the CRL until the next scheduled generation cycle, potentially enabling continued use of certificates that should have been invalidated.
The technical root cause of this vulnerability lies in the concurrent processing model of the Certificate Server where the CRL generation process does not properly synchronize with real-time revocation events. When a certificate is revoked while a CRL is being constructed, the system fails to incorporate the new revocation into the current CRL being generated, leading to a race condition between the revocation processing and CRL generation threads. This design flaw creates a window of opportunity where certificates that have been marked for revocation remain valid within the context of the currently published CRL, effectively undermining the trust model that CRLs are designed to maintain. The vulnerability maps directly to CWE-362, which addresses race conditions in concurrent systems, and specifically relates to CWE-367, concerning improper restriction of operations within a single service or process.
The operational impact of this vulnerability extends beyond simple certificate validation failures, creating potential security risks that could be exploited by malicious actors. An attacker who gains knowledge of a revoked certificate's continued validity within the system could potentially use that certificate to bypass authentication mechanisms, access restricted resources, or perform unauthorized transactions. The delay in CRL updates could also complicate compliance requirements in regulated environments where immediate certificate status updates are mandatory. This vulnerability particularly affects systems relying on timely certificate revocation for security operations, potentially allowing credential compromise that could persist until the next CRL generation cycle. The issue aligns with ATT&CK technique T1556.003, which covers credential access through manipulation of authentication systems, and could be leveraged as part of broader credential compromise strategies.
Mitigation strategies for CVE-2007-4994 require immediate attention through patching of the affected Red Hat Certificate System components, with administrators prioritizing the application of vendor security updates. Organizations should implement monitoring solutions to detect potential CRL generation delays and establish more frequent CRL update schedules to minimize the window of vulnerability. The system configuration should be reviewed to ensure proper synchronization mechanisms are in place between revocation processing and CRL generation processes. Additionally, implementing alternative certificate validation methods such as Online Certificate Status Protocol (OCSP) stapling can provide more immediate revocation status information, serving as a compensating control while the primary vulnerability is addressed. Security teams should also conduct regular audits of certificate management processes to identify similar concurrency issues in other cryptographic components and establish incident response procedures specifically addressing certificate revocation delays.