CVE-2018-5539 in BIG-IP ASM
Summary
by MITRE
Under certain conditions, on F5 BIG-IP ASM 13.0.0-13.1.0.7, 12.1.0-12.1.3.5, 11.6.0-11.6.3.1, 11.5.1-11.5.6, or 11.2.1, when processing CSRF protections, the BIG-IP ASM bd process may restart and produce a core file.
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2018-5539 represents a critical stability issue within F5 BIG-IP Application Security Manager (ASM) components that affects multiple versions of the F5 BIG-IP platform. This vulnerability specifically targets the bd process responsible for handling Cross-Site Request Forgery (CSRF) protections, creating a potential denial of service condition that could disrupt critical web application security functions. The affected versions span across several major releases including 13.0.0 through 13.1.0.7, 12.1.0 through 12.1.3.5, 11.6.0 through 11.6.3.1, 11.5.1 through 11.5.6, and 11.2.1, indicating a widespread impact across the F5 BIG-IP ASM product line. The vulnerability manifests when the system processes specific CSRF protection mechanisms, causing the bd process to terminate unexpectedly and generate core dump files that can consume system resources and potentially lead to further instability.
The technical flaw underlying CVE-2018-5539 stems from improper handling of CSRF protection logic within the BIG-IP ASM module, where the bd process fails to properly manage memory or processing states when encountering certain input patterns during CSRF validation. This process termination behavior creates a cascading effect that can potentially impact the overall availability of the application security services provided by the BIG-IP device, as the bd process is integral to the ASM functionality that monitors and protects web applications from various attack vectors. The vulnerability's exploitation typically occurs through crafted requests that trigger the specific code path involving CSRF protection handling, causing the process to crash and restart automatically while generating core files that may persist and consume system resources. This behavior aligns with CWE-122, which addresses heap-based buffer overflow conditions, and represents a process termination vulnerability that can be leveraged to create denial of service conditions.
The operational impact of CVE-2018-5539 extends beyond simple service disruption, as it directly affects the integrity of web application security monitoring and protection capabilities that organizations rely upon for defending against sophisticated cyber threats. When the bd process restarts and produces core files, it can lead to temporary unavailability of ASM features, potentially leaving web applications exposed to CSRF attacks and other security vulnerabilities during the recovery period. Network administrators and security teams may experience challenges in monitoring and maintaining consistent security posture across their infrastructure, particularly in environments where F5 BIG-IP devices serve as critical security controls. The generation of core files can also consume significant storage space and may interfere with normal system operations, potentially creating additional operational overhead for maintenance and troubleshooting activities. This vulnerability particularly impacts organizations that depend heavily on F5 BIG-IP ASM for web application protection, as the disruption can occur without explicit warning signs and may go unnoticed until the service is actually required.
Organizations affected by CVE-2018-5539 should prioritize applying F5's official security patches and updates as recommended in their security advisories, which typically include version-specific fixes that address the process termination issue within the bd component. System administrators should also implement monitoring solutions to detect process restarts and core file generation that may indicate exploitation attempts, as these events can serve as indicators of potential security incidents. Network segmentation and access control measures should be reviewed to limit exposure to potential attackers who might attempt to exploit this vulnerability through crafted requests designed to trigger the affected code path. Additionally, organizations should consider implementing redundant security controls and backup systems to maintain application security posture during any necessary maintenance windows or patch deployment activities. The vulnerability's classification under the ATT&CK framework would likely fall under the T1499 category for network denial of service, with potential implications for T1566 related to credential access through application security bypass techniques, making comprehensive remediation and monitoring essential for maintaining overall security posture.