CVE-2017-6150 in BIG-IP
Summary
by MITRE
Under certain conditions for F5 BIG-IP systems 13.0.0 or 12.1.0 - 12.1.3.1, using FastL4 profiles, when the Reassemble IP Fragments option is disabled (default), some specific large fragmented packets may restart the Traffic Management Microkernel (TMM).
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2017-6150 affects F5 BIG-IP systems running specific versions including 13.0.0 and 12.1.0 through 12.1.3.1 when utilizing FastL4 profiles with the Reassemble IP Fragments option disabled. This issue represents a critical denial of service condition that can be exploited to disrupt network services by causing the Traffic Management Microkernel to restart. The vulnerability stems from how the system handles large fragmented IP packets when the reassembly mechanism is disabled, creating a scenario where specific packet sequences can trigger unexpected system behavior.
The technical flaw manifests in the Traffic Management Microkernel's processing of IP fragments when the Reassemble IP Fragments option is disabled in FastL4 profiles. When large fragmented packets are received under these conditions, the system's packet processing logic fails to properly handle the fragmentation state, leading to an internal error that causes the TMM to restart. This restart effectively terminates active connections and disrupts network service availability. The vulnerability is particularly concerning because it can be triggered by specific packet characteristics including size and fragmentation patterns without requiring authentication or specialized privileges.
The operational impact of CVE-2017-6150 extends beyond simple service disruption as it can lead to complete network availability loss for affected F5 BIG-IP systems. When the Traffic Management Microkernel restarts, all active connections are terminated and the system enters a recovery state that can last several minutes, depending on system configuration and load. This disruption affects all services running through the affected FastL4 profiles, including application delivery, load balancing, and traffic optimization functions. The vulnerability can be exploited remotely, making it particularly dangerous in environments where external network access is possible, and can be amplified by sending multiple fragmented packets to overwhelm the system's processing capabilities.
Organizations affected by CVE-2017-6150 should implement immediate mitigations including enabling the Reassemble IP Fragments option in FastL4 profiles or applying the vendor-provided security patches. The recommended approach involves either modifying the FastL4 profile configuration to enable IP fragment reassembly or upgrading to patched versions of the F5 BIG-IP software. Network administrators should also consider implementing intrusion detection systems to monitor for unusual packet patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a denial of service scenario that can be categorized under ATT&CK technique T1499 for network disruption. Organizations should conduct thorough testing of any configuration changes to ensure that enabling IP fragment reassembly does not introduce new security risks or performance degradation in their specific network environments.