CVE-2024-39778 in BIG-IP
Summary
by MITRE • 08/14/2024
When a stateless virtual server is configured on BIG-IP system with a High-Speed Bridge (HSB), undisclosed requests can cause TMM to terminate.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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Analysis
by VulDB Data Team • 08/20/2024
The vulnerability identified as CVE-2024-39778 represents a critical stability issue within F5 Networks BIG-IP systems when specific configuration patterns are deployed. This flaw manifests in environments where stateless virtual servers are configured alongside High-Speed Bridge functionality, creating a scenario where certain network requests can trigger unexpected termination of the Traffic Management Microkernel (TMM) process. The vulnerability specifically affects systems that have not reached their End of Technical Support lifecycle, indicating that F5 has identified this as a significant concern requiring immediate attention from supported customers.
The technical root cause of this vulnerability lies in the interaction between the stateless virtual server configuration and the High-Speed Bridge implementation within the BIG-IP architecture. When traffic flows through this particular combination of features, certain request patterns that are not properly handled by the system's processing logic can lead to memory corruption or resource management failures within TMM. This results in the TMM process terminating unexpectedly, which subsequently disrupts all network services handled by that specific virtual server configuration. The term "undisclosed requests" suggests that the vulnerability may be triggered by specific packet structures, timing conditions, or request sequences that are not well-documented or predictable, making it particularly challenging to defend against through conventional means.
From an operational impact perspective, this vulnerability poses significant risk to network availability and service continuity. When TMM terminates, all active connections through the affected virtual server are dropped, requiring clients to reestablish their sessions and potentially causing service disruption for end users. The impact extends beyond simple service interruption as the termination of TMM can also affect other virtual servers on the same BIG-IP system if the process restart mechanism does not properly isolate the affected configuration. Network administrators may experience cascading failures if multiple virtual servers share the same TMM instance or if the system's automatic recovery mechanisms are insufficient to restore service quickly. The vulnerability essentially creates a denial-of-service condition that can be exploited by attackers to disrupt network services or can occur accidentally through normal traffic patterns.
Security professionals should note that this vulnerability aligns with CWE-248, which addresses "Uncaught Exception" conditions in software systems, and may also relate to CWE-129, "Improper Validation of Array Index," if the termination occurs due to improper resource handling. The attack surface for this vulnerability could be classified under ATT&CK technique T1499.004, "Endpoint Denial of Service," as it specifically targets the stability and availability of network endpoint services. Organizations should prioritize immediate patching of affected systems and implement monitoring for unusual TMM termination events that could indicate exploitation attempts. Additionally, network segmentation strategies should be considered to limit the scope of potential impact should the vulnerability be exploited, and administrators should carefully review all virtual server configurations that utilize stateless server settings combined with High-Speed Bridge functionality to identify and remediate affected deployments before the patch is applied.
The vulnerability demonstrates the complexity of modern application delivery controllers where multiple advanced features interact in ways that can create unexpected failure conditions. This particular issue highlights the importance of comprehensive testing of feature combinations, especially in enterprise environments where complex configurations are common. Organizations should also consider implementing additional monitoring and alerting mechanisms specifically designed to detect TMM process termination events and correlate them with network traffic patterns to identify potential exploitation attempts. The incident underscores the necessity of maintaining current support contracts with vendors to ensure timely access to security patches and updates that address these types of critical stability issues.