CVE-2013-6016 in Big-ip Protocol Security Module
Summary
by MITRE
The Traffic Management Microkernel (TMM) in F5 BIG-IP LTM, APM, ASM, Edge Gateway, GTM, Link Controller, and WOM 10.0.0 through 10.2.2 and 11.0.0; Analytics 11.0.0; PSM 9.4.0 through 9.4.8, 10.0.0 through 10.2.4, and 11.0.0 through 11.4.1; and WebAccelerator 9.4.0 through 9.4.8, 10.0.0 through 10.2.4, and 11.0.0 through 11.3.0 might change a TCP connection to the ESTABLISHED state before receiving the ACK packet, which allows remote attackers to cause a denial of service (SIGFPE or assertion failure and TMM restart) via unspecified vectors.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability described in CVE-2013-6016 represents a critical flaw in the Traffic Management Microkernel (TMM) component of F5 BIG-IP products, affecting multiple modules including Local Traffic Manager, Application Security Manager, and Global Traffic Manager. This issue stems from improper handling of TCP connection state transitions within the network processing stack, creating a condition where the system can prematurely transition a connection to the ESTABLISHED state without receiving the required acknowledgment packet from the remote peer. The flaw exists across multiple versions of F5's BIG-IP platform, specifically impacting versions 10.0.0 through 10.2.2 and 11.0.0, as well as various releases of Analytics, PSM, and WebAccelerator modules, making it a widespread concern affecting enterprise network infrastructure. The vulnerability operates at the network protocol level and demonstrates a fundamental breakdown in TCP state machine implementation within the F5 platform's traffic processing engine.
The technical implementation of this vulnerability allows remote attackers to exploit the improper TCP connection state handling by manipulating network packets in a way that triggers the TMM to advance connection states prematurely. When the TMM receives a TCP packet that should normally result in a connection transition to ESTABLISHED but fails to validate that the corresponding ACK packet has been properly received, it can execute invalid operations that lead to system crashes. This behavior manifests as either SIGFPE (floating point exception) or assertion failures within the TMM process, ultimately resulting in complete service disruption through TMM restarts. The flaw essentially creates a condition where the system's TCP stack implementation becomes vulnerable to crafted packet sequences that exploit race conditions or improper state validation logic, aligning with CWE-119 (Improper Access to Memory) and CWE-682 (Incorrect Calculation) classifications. The vulnerability's impact is particularly severe because it affects core network processing functionality that handles thousands of concurrent connections in enterprise environments.
The operational impact of CVE-2013-6016 extends beyond simple denial of service to potentially compromise entire network infrastructure availability and stability. Organizations relying on F5 BIG-IP appliances for critical traffic management functions face the risk of service interruptions that can cascade across their network architecture, affecting application availability, user access, and business continuity. The vulnerability's remote exploitability means that attackers can trigger the condition from outside the network perimeter without requiring authentication or privileged access, making it particularly dangerous in exposed network environments. System administrators may experience unexpected TMM restarts that can disrupt ongoing connections, leading to session drops and application timeouts. The attack vectors remain unspecified in the CVE description, suggesting that multiple packet manipulation techniques could trigger the condition, which complicates defensive measures and makes the vulnerability more difficult to predict and prevent. This type of vulnerability aligns with ATT&CK technique T1499.004 (Endpoint Denial of Service) and T1071.004 (Application Layer Protocol: DNS) when considering the network protocol exploitation aspects.
Organizations affected by this vulnerability should implement immediate mitigations including applying the vendor-provided security patches and updates released for the affected F5 BIG-IP versions. Network segmentation and access controls should be enhanced to limit exposure of vulnerable systems to untrusted networks, while monitoring systems should be configured to detect unusual TMM restart patterns or connection state anomalies. The implementation of rate limiting and connection tracking mechanisms can help reduce the effectiveness of exploitation attempts, though these are not complete defenses against the core protocol-level flaw. Security teams should also consider deploying intrusion detection systems capable of identifying the specific packet patterns that could trigger the vulnerability, particularly focusing on TCP handshake sequences and state transition anomalies. Additionally, maintaining detailed operational procedures for handling TMM restarts and implementing automated recovery mechanisms can help minimize the impact of successful exploitation attempts. The vulnerability's presence in multiple F5 modules emphasizes the need for comprehensive patch management across all affected products and versions within the enterprise environment.