CVE-2019-6672 in BIG-IP AFM
Summary
by MITRE
On BIG-IP AFM 15.0.0-15.0.1, 14.0.0-14.1.2, and 13.1.0-13.1.3.1, when bad-actor detection is configured on a wildcard virtual server on platforms with hardware-based sPVA, the performance of the BIG-IP AFM system is degraded.
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Analysis
by VulDB Data Team • 03/05/2024
The vulnerability described in CVE-2019-6672 represents a significant performance degradation issue within F5 Networks BIG-IP Advanced Firewall Manager (AFM) implementations. This flaw specifically impacts systems running AFM versions 15.0.0 through 15.0.1, 14.0.0 through 14.1.2, and 13.1.0 through 13.1.3.1 when deployed on hardware platforms utilizing sPVA (software-based Packet Virtual Accelerator) technology. The issue manifests when bad-actor detection mechanisms are configured on wildcard virtual servers, creating a scenario where system performance becomes substantially compromised. This vulnerability falls under the category of performance degradation rather than direct exploitation, making it particularly insidious as it can go unnoticed while silently impacting system operations and network throughput.
The technical root cause of this vulnerability stems from how the AFM system handles bad-actor detection configurations when combined with wildcard virtual server definitions on sPVA-enabled hardware platforms. When wildcard virtual servers are configured with bad-actor detection rules, the system's processing logic becomes inefficient, leading to excessive resource consumption and reduced throughput. This behavior creates a condition where legitimate network traffic processing becomes significantly slower, effectively degrading the overall performance of the firewall system. The issue is specifically tied to hardware-based sPVA acceleration, indicating that the problem lies in the interaction between software configuration and hardware acceleration capabilities. According to CWE classification, this vulnerability relates to CWE-20: Improper Input Validation, as the system fails to properly validate or handle the specific combination of wildcard virtual server configurations with bad-actor detection on sPVA platforms. The performance degradation occurs at the system level rather than at the application layer, making it a critical concern for network infrastructure reliability.
The operational impact of CVE-2019-6672 extends beyond simple performance degradation to potentially compromise network security operations and business continuity. Organizations relying on BIG-IP AFM systems for network protection may experience reduced network throughput, increased latency in traffic processing, and potential service degradation that could affect critical applications and user experiences. The vulnerability's presence on multiple version streams (13.x, 14.x, and 15.x) indicates a widespread issue affecting various deployment scenarios, including legacy systems that may not have been updated to newer versions. Security operations teams may find that their firewall systems become less effective at handling traffic loads, potentially creating bottlenecks that could impact overall network security posture and response capabilities. From an ATT&CK framework perspective, this vulnerability could be leveraged by adversaries to create network disruption or denial-of-service conditions, as the performance degradation could mask actual security incidents or make systems more susceptible to other attacks due to reduced processing capabilities.
Organizations affected by this vulnerability should implement immediate mitigation strategies focusing on configuration changes and system monitoring. The primary recommendation involves avoiding the combination of bad-actor detection rules with wildcard virtual servers on sPVA-enabled platforms until appropriate patches are deployed. System administrators should consider disabling or reconfiguring bad-actor detection on wildcard virtual servers while maintaining security controls through alternative means. Monitoring network performance and traffic processing metrics becomes crucial for early detection of degradation symptoms. Additionally, organizations should prioritize updating their BIG-IP AFM systems to versions that address this specific vulnerability, as F5 has released patches and updates to resolve the issue. The vulnerability demonstrates the importance of thorough testing when implementing complex security configurations, particularly when combining multiple security features on hardware-accelerated platforms. Regular security assessments and vulnerability scanning should include verification of virtual server configurations to prevent this specific combination from being deployed in production environments.