CVE-2018-15319 in BIG-IP
Summary
by MITRE
On BIG-IP 14.0.0-14.0.0.2, 13.0.0-13.1.1.1, or 12.1.0-12.1.3.6, malicious requests made to virtual servers with an HTTP profile can cause the TMM to restart. The issue is exposed with the non-default "normalize URI" configuration options used in iRules and/or BIG-IP LTM policies.
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Analysis
by VulDB Data Team • 06/04/2023
The vulnerability identified as CVE-2018-15319 represents a critical denial of service flaw within F5 BIG-IP systems that affects multiple version ranges including 14.0.0 through 14.0.0.2, 13.0.0 through 13.1.1.1, and 12.1.0 through 12.1.3.6. This weakness specifically targets the Traffic Management Microkernel (TMM) component which is responsible for processing network traffic in F5's load balancing and application delivery solutions. The vulnerability manifests when maliciously crafted HTTP requests are processed by virtual servers configured with HTTP profiles, leading to unexpected system restarts that can severely disrupt network services and application availability.
The technical root cause of this vulnerability lies in the improper handling of URI normalization within the TMM processing pipeline. When specific non-default configuration options are enabled through iRules or BIG-IP Local Traffic Manager policies, the system fails to properly validate or sanitize incoming URI data before processing it through the normalization routines. This creates a condition where malformed or specially crafted URI sequences can trigger memory corruption or stack overflow conditions within the TMM process, ultimately causing the entire system to restart. The vulnerability is particularly concerning because it can be exploited through standard HTTP traffic without requiring authentication or privileged access, making it a significant threat to network availability.
The operational impact of CVE-2018-15319 extends beyond simple service disruption to encompass potential business continuity issues and security posture degradation. Network administrators may experience unexpected downtime as TMM restarts occur without warning, potentially leading to service interruptions for critical applications. The vulnerability also creates opportunities for attackers to perform sustained denial of service attacks by repeatedly sending malicious requests, effectively exhausting system resources and maintaining service unavailability. Additionally, the restart behavior can cause loss of session state information, connection tracking data, and other runtime configurations that are essential for proper system operation and maintaining network service integrity.
Organizations affected by this vulnerability should implement immediate mitigations including disabling the problematic non-default URI normalization options in iRules and LTM policies, applying the latest security patches provided by F5, and implementing network-level controls to filter or rate-limit suspicious HTTP traffic patterns. The mitigation strategy should also include monitoring for unusual restart patterns and implementing intrusion detection systems that can identify the specific attack vectors associated with this vulnerability. From a cybersecurity perspective, this vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and memory management issues, while also mapping to ATT&CK techniques involving service stoppage and denial of service operations that can be used to compromise system availability and maintain access to network resources.