CVE-2005-4737 in DB2 Universal Database
Summary
by MITRE
IBM DB2 Universal Database (UDB) 820 before ESE AIX 5765F4100 allows remote authenticated users to cause a denial of service (CPU consumption) by "abnormally" terminating a connection, which prevents db2agents from being properly cleared.
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Analysis
by VulDB Data Team • 08/02/2017
IBM DB2 Universal Database version 820 running on AIX operating system presents a significant denial of service vulnerability that affects system availability and performance. This vulnerability specifically targets the database agent management mechanism within the DB2 architecture, where authenticated remote users can exploit a flaw in connection termination handling to consume excessive CPU resources and ultimately cause system instability. The issue arises from the improper clearing of db2agents when connections are terminated in an abnormal manner, creating a resource leak that accumulates over time and degrades system performance. The vulnerability is classified under CWE-400 as an Uncontrolled Resource Consumption, specifically manifesting as a denial of service condition that impacts system availability.
The technical flaw exists in the connection management subsystem of DB2 UDB where the database agent process fails to properly clean up its resources when a connection is abruptly terminated by a client. When an authenticated user establishes a connection to the database and then terminates it abnormally, the system does not properly release the associated db2agent processes, leading to resource accumulation and subsequent CPU exhaustion. This behavior is particularly concerning because it requires only authenticated access to exploit, making it accessible to users with valid database credentials. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries leverage legitimate system access to disrupt service availability through resource exhaustion.
The operational impact of this vulnerability extends beyond simple service disruption to encompass significant performance degradation and potential system instability. As db2agents accumulate without proper cleanup, the database server experiences increased CPU utilization and memory consumption, which can cascade into broader system performance issues affecting other database operations and potentially causing complete system unresponsiveness. The vulnerability is particularly dangerous in production environments where database availability is critical for business operations, as it can be exploited by malicious insiders or compromised accounts to systematically degrade service quality. Organizations may observe gradual performance degradation over time before experiencing complete service disruption, making early detection and mitigation challenging. The resource consumption pattern suggests that this vulnerability could be exploited to create a sustained denial of service condition that requires system restart to resolve completely.
Mitigation strategies for this vulnerability should focus on implementing proper connection management practices and monitoring for abnormal connection termination patterns. Database administrators should ensure that all DB2 instances are updated to the latest available patches and service levels that address this specific resource leak issue. System monitoring should include tracking of db2agent processes and CPU utilization patterns to detect potential exploitation attempts. Network-level controls can be implemented to limit connection rates and detect abnormal termination patterns that may indicate exploitation. Additionally, access controls should be strictly enforced to minimize the risk of unauthorized users exploiting this vulnerability, as the attack requires authenticated access to the database system. Regular system maintenance and patch management procedures should include verification that the specific vulnerability has been resolved through proper testing and validation. Organizations should also consider implementing database activity monitoring solutions that can detect and alert on anomalous connection termination behaviors that may indicate exploitation attempts.