CVE-2019-6684 in BIG-IP
Summary
by MITRE
On versions 15.0.0-15.0.1.1, 14.0.0-14.1.2.2, 13.1.0-13.1.3.1, 12.1.0-12.1.5, and 11.5.2-11.6.5.1, under certain conditions, a multi-bladed BIG-IP Virtual Clustered Multiprocessing (vCMP) may drop broadcast packets when they are rebroadcast to the vCMP guest secondary blades. An attacker can leverage the fragmented broadcast IP packets to perform any type of fragmentation-based attack.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2019-6684 affects F5 BIG-IP systems across multiple software versions including 15.0.0-15.0.1.1, 14.0.0-14.1.2.2, 13.1.0-13.1.3.1, 12.1.0-12.1.5, and 11.5.2-11.6.5.1, representing a significant security flaw within the virtualized networking infrastructure of these critical network appliances. This vulnerability specifically impacts the vCMP functionality which enables multiple virtual machines to operate within a single physical BIG-IP device, creating a clustered multiprocessing environment that enhances resource utilization and scalability.
The technical flaw manifests in the handling of broadcast packets within the vCMP environment where the system fails to properly process rebroadcast packets destined for secondary blades in the virtual cluster. When broadcast packets are fragmented and subsequently rebroadcast to vCMP guest secondary blades, the system exhibits inconsistent behavior that results in packet drops. This packet loss occurs under specific operational conditions that are triggered by the fragmentation and redistribution processes inherent to virtualized networking environments. The vulnerability stems from inadequate handling of IP packet fragmentation within the vCMP framework, creating a pathway for attackers to exploit the system's packet processing mechanisms.
The operational impact of this vulnerability extends beyond simple packet loss, as it enables attackers to perform fragmentation-based attacks that can compromise network integrity and availability. Attackers can leverage the fragmented broadcast IP packets to execute various malicious activities including but not limited to network disruption, service degradation, and potential data exfiltration. The vulnerability's exploitation capability is particularly concerning because it targets fundamental networking protocols and packet handling mechanisms that are essential for proper network operation. This weakness can be particularly damaging in environments where the BIG-IP system serves as a critical network component for load balancing, application delivery, or security services.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which addresses buffer overflow conditions, and represents a specific implementation flaw in packet processing that could be exploited to cause denial of service or information disclosure. The attack surface is particularly broad given that BIG-IP systems are deployed across numerous enterprise environments and are often critical infrastructure components. The vulnerability's classification under ATT&CK framework would fall within the T1498 category for Network Denial of Service, as the flawed packet handling mechanism can be leveraged to disrupt network services. Organizations utilizing affected BIG-IP versions must implement immediate mitigation strategies including applying vendor patches, implementing network segmentation, and monitoring for anomalous packet behavior patterns that could indicate exploitation attempts. The vulnerability underscores the importance of maintaining up-to-date security patches and conducting regular vulnerability assessments of critical network infrastructure components.