CVE-2020-5024 in DB2
Summary
by MITRE • 03/11/2021
IBM DB2 for Linux, UNIX and Windows (includes DB2 Connect Server) 9.7, 10.1, 10.5, 11.1, and 11.5 could allow an unauthenticated attacker to cause a denial of service due a hang in the SSL handshake response. IBM X-Force ID: 193660.
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Analysis
by VulDB Data Team • 03/31/2021
IBM DB2 database systems across multiple versions including 9.7, 10.1, 10.5, 11.1, and 11.5 contain a critical vulnerability in their SSL handshake implementation that can be exploited by unauthenticated attackers to cause denial of service conditions. This vulnerability specifically affects the SSL/TLS protocol handling within the DB2 Connect Server component, which serves as the gateway for remote database connections. The flaw manifests as a hang during the SSL handshake process, where the system becomes unresponsive and unable to process additional connection requests. This behavior aligns with CWE-400, which categorizes improper handling of resource exhaustion conditions in network protocols. The vulnerability exists because the system fails to properly validate and process certain SSL handshake messages, particularly when dealing with malformed or unexpected SSL protocol versions during the initial connection negotiation phase. Attackers can exploit this weakness by establishing SSL connections with malformed handshake parameters, causing the database server to enter a state where it cannot properly respond to subsequent connection attempts. The operational impact is severe as it can effectively shut down database access for legitimate users, creating a denial of service condition that affects business continuity and database availability. Organizations relying on DB2 for mission-critical applications face significant risk since the vulnerability can be exploited without requiring authentication credentials, making it particularly dangerous in environments where database servers are exposed to external networks. This vulnerability maps to several ATT&CK techniques including T1499.004 for network denial of service and T1566.001 for initial access through network services. The attack surface is broad as it affects all supported versions of DB2 and can be triggered through standard network connections, making it difficult to detect and prevent. The SSL handshake hang occurs because the system's SSL implementation lacks proper timeout mechanisms and input validation, allowing malformed data to cause indefinite blocking of connection processing threads. This issue represents a fundamental flaw in the protocol handling layer that affects the core functionality of the database server's network security features. Organizations should implement immediate mitigations including applying the relevant IBM security patches, configuring network firewalls to restrict access to DB2 ports, and implementing connection rate limiting to prevent exploitation. The vulnerability demonstrates the importance of proper protocol implementation and resource management in database security architectures, as it directly impacts the availability and reliability of enterprise database services. System administrators must also consider implementing monitoring solutions that can detect unusual connection patterns and SSL handshake failures that may indicate exploitation attempts. The incident highlights the critical need for comprehensive security testing of network protocol implementations in database systems and underscores the potential for seemingly minor protocol handling flaws to result in significant operational disruptions. This vulnerability serves as a reminder of the importance of maintaining up-to-date security patches and the necessity of robust input validation mechanisms in security-critical components of enterprise software infrastructure.