CVE-2018-15330 in BIG-IP
Summary
by MITRE
On BIG-IP 14.0.0-14.0.0.2, 13.0.0-13.1.1.1, or 12.1.0-12.1.3.7, when a virtual server using the inflate functionality to process a gzip bomb as a payload, the BIG-IP system will experience a fatal error and may cause the Traffic Management Microkernel (TMM) to produce a core file.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/20/2023
This vulnerability exists within F5 BIG-IP systems running specific software versions where the Traffic Management Microkernel (TMM) fails to properly handle gzip compressed payloads that contain excessive data compression ratios. The flaw occurs when a virtual server configured with inflate functionality processes maliciously crafted gzip bomb payloads, leading to system instability and potential service disruption. The vulnerability represents a denial of service condition that can be exploited through carefully constructed compressed data that, when decompressed, consumes excessive system resources.
The technical mechanism behind this vulnerability involves the TMM's handling of gzip decompression operations without adequate resource limits or input validation. When processing a gzip bomb, the system attempts to decompress data that has been artificially compressed to an extremely high ratio, causing memory exhaustion and subsequent system crashes. This behavior aligns with CWE-400, which addresses unchecked resource consumption, and demonstrates how improper handling of compressed data can lead to system instability. The vulnerability specifically affects the TMM component responsible for traffic processing, making it particularly dangerous in production environments where continuous service availability is critical.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire BIG-IP system's stability and availability. When the TMM generates core files due to memory exhaustion, it indicates that the system has reached a critical state where normal operations cannot continue. Attackers can exploit this weakness by sending carefully crafted requests that trigger the gzip decompression process with maliciously inflated payloads, potentially causing multiple system restarts or requiring manual intervention to recover. This vulnerability also maps to ATT&CK technique T1499.004 which covers "Evasion: File and Directory Permissions Modification" and T1070.004 which addresses "Indicator Removal on Host: File Deletion" through the system's response to corrupted state.
Mitigation strategies for this vulnerability include implementing strict resource limits on decompression operations, configuring appropriate input validation for compressed data, and applying the latest security patches provided by F5. Organizations should also consider implementing network-level controls to monitor and restrict the size of compressed data passing through their BIG-IP systems. Additionally, system administrators should configure logging and monitoring to detect unusual memory usage patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper resource management in network infrastructure components and highlights the need for comprehensive input validation across all data processing functions within critical system components. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other system components that might be susceptible to similar resource exhaustion attacks.