CVE-2013-6747 in DB2
Summary
by MITRE
IBM GSKit 7.x before 7.0.4.48 and 8.x before 8.0.50.16, as used in IBM Security Directory Server (ISDS) and Tivoli Directory Server (TDS), allows remote attackers to cause a denial of service (application crash or hang) via a malformed X.509 certificate chain.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2013-6747 affects IBM GSKit versions 7.x prior to 7.0.4.48 and 8.x prior to 8.0.50.16 when utilized in IBM Security Directory Server and Tivoli Directory Server environments. This issue represents a critical denial of service vulnerability that stems from insufficient input validation within the X.509 certificate processing functionality. The flaw specifically manifests when the system encounters malformed certificate chains during secure communication establishment, leading to application instability and potential system unavailability.
The technical root cause of this vulnerability lies in the improper handling of malformed X.509 certificate chains within the GSKit cryptographic library. When a remote attacker submits a specially crafted certificate chain that contains invalid or malformed structures, the GSKit component fails to properly validate the input before processing. This lack of robust input validation creates a condition where the application encounters unexpected data structures that cause memory corruption or infinite loop scenarios. The vulnerability operates at the protocol level where certificate validation occurs during SSL/TLS handshakes, making it particularly dangerous as it can be triggered during normal authentication processes. According to CWE classification, this represents a weakness in input validation and memory management, specifically CWE-129 and CWE-125, which are common categories for denial of service vulnerabilities in cryptographic libraries.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire directory services infrastructure. When exploited, the vulnerability can cause complete application crashes or indefinite hangs, effectively rendering the directory server unavailable to legitimate users and applications. This denial of service condition affects authentication services, which are fundamental to enterprise security operations, potentially allowing attackers to disrupt business continuity and access control mechanisms. The vulnerability is particularly concerning in environments where directory services are critical for identity management, single sign-on operations, and secure application access. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing via Service), as attackers can leverage this weakness to disrupt services while potentially using the disruption as a cover for other attacks.
Organizations affected by this vulnerability should prioritize immediate patching of their IBM GSKit installations to versions 7.0.4.48 or 8.0.50.16, respectively. Network administrators should implement monitoring for unusual certificate validation patterns and establish alerting mechanisms for potential exploitation attempts. Additionally, implementing certificate validation policies that reject malformed certificates at the network perimeter can provide an additional layer of defense. System administrators should also consider implementing redundant directory services and failover mechanisms to maintain availability during potential exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date cryptographic libraries and the potential impact that insecure certificate handling can have on enterprise security infrastructure.