CVE-2017-6135 in BIG-IP
Summary
by MITRE
In F5 BIG-IP LTM, AAM, AFM, Analytics, APM, ASM, DNS, GTM, Link Controller, PEM and WebSafe software version 13.0.0, a slow memory leak as a result of undisclosed IPv4 or IPv6 packets sent to BIG-IP management port or self IP addresses may lead to out of memory (OOM) conditions.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability described in CVE-2017-6135 represents a critical memory management flaw within F5 BIG-IP systems that affects multiple modules including Local Traffic Manager AAM AFM Analytics APM ASM DNS GTM Link Controller PEM and WebSafe. This issue manifests as a slow memory leak triggered by specifically crafted IPv4 or IPv6 packets directed toward the BIG-IP management port or self IP addresses. The vulnerability operates at the network protocol level and demonstrates the classic characteristics of a resource exhaustion attack where legitimate network traffic is exploited to consume system resources over time. The affected versions including 13.0.0 indicate this was a significant flaw present in a major release that likely impacted numerous enterprise deployments. This type of vulnerability falls under the CWE-400 category of Uncontrolled Resource Consumption also known as a resource leak or memory leak, which is a fundamental weakness in system design that allows attackers to gradually deplete available memory resources.
The technical exploitation of this vulnerability occurs when malicious or malformed IPv4 and IPv6 packets are transmitted to the management interface or self IP addresses of the BIG-IP system. These packets contain undisclosed characteristics that trigger an internal processing loop within the F5 software that fails to properly release allocated memory structures. The memory leak is described as slow which indicates that the system does not immediately crash but rather consumes memory incrementally over time until the system reaches an out of memory condition. This characteristic makes the vulnerability particularly dangerous as it can remain undetected for extended periods while gradually degrading system performance and eventually leading to complete service disruption. The attack vector specifically targets the management port and self IP addresses which are critical interfaces for system administration and network configuration, making this vulnerability particularly severe as it can impact both operational functionality and security posture.
The operational impact of CVE-2017-6135 extends beyond simple service disruption to encompass broader security and availability concerns. When the system reaches out of memory conditions, it can result in complete system crashes, requiring manual intervention and potentially causing extended downtime for critical network services. Organizations relying on F5 BIG-IP systems for load balancing application delivery and security services face significant risk of service degradation or complete failure. The vulnerability can be exploited through various network interfaces and does not require authentication or specialized access privileges, making it accessible to attackers with basic network connectivity. This characteristic aligns with ATT&CK technique T1499.004 for Network Denial of Service and demonstrates how memory exhaustion attacks can be leveraged to compromise system availability. The slow nature of the leak also means that traditional monitoring systems may not immediately detect the degradation, allowing the attack to progress unnoticed until system failure occurs.
Mitigation strategies for CVE-2017-6135 should focus on both immediate protective measures and long-term system hardening approaches. Organizations should implement network segmentation to restrict access to management interfaces and self IP addresses, limiting the attack surface available to potential adversaries. Packet filtering rules and access control lists should be configured to monitor and restrict incoming traffic to these critical interfaces, particularly focusing on unusual packet patterns that might trigger the memory leak. The most effective immediate solution involves applying the vendor-provided security patches and updates that address the underlying memory management flaw in the F5 software. System administrators should also implement enhanced monitoring and alerting for memory usage patterns on BIG-IP systems, enabling early detection of potential exploitation attempts. Network administrators should consider implementing rate limiting and connection tracking mechanisms to prevent excessive packet processing that could trigger the vulnerability. Additionally, regular system health checks and memory usage monitoring should be established as part of routine maintenance procedures to detect anomalous behavior before it leads to complete system failure. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how seemingly minor protocol handling issues can result in significant availability impacts.