CVE-2018-5526 in BIG-IP ASM
Summary
by MITRE
Under certain conditions, on F5 BIG-IP ASM 13.1.0-13.1.0.5, Behavioral DOS (BADOS) protection may fail during an attack.
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Analysis
by VulDB Data Team • 03/19/2023
The vulnerability identified as CVE-2018-5526 represents a critical weakness in the F5 BIG-IP Application Security Manager (ASM) version 13.1.0 through 13.1.0.5 where the Behavioral DOS (BADOS) protection mechanism fails to properly mitigate certain types of denial of service attacks. This flaw specifically affects the system's ability to detect and respond to malicious traffic patterns that could potentially overwhelm the device's processing capabilities. The vulnerability resides within the behavioral analysis engine that is designed to identify and block suspicious activities by monitoring traffic patterns and user behavior. When subjected to particular attack vectors, the system's protective mechanisms become ineffective, allowing malicious actors to exploit the weakness and potentially cause service disruption.
The technical implementation of this vulnerability stems from insufficient validation and processing of specific traffic patterns within the BADOS protection framework. The behavioral analysis system relies on predefined thresholds and pattern recognition algorithms to identify potential threats, but these mechanisms contain a logical flaw that prevents proper execution under certain attack conditions. This failure manifests when attackers craft malicious requests that exploit edge cases in the behavioral analysis logic, causing the system to either misclassify legitimate traffic as malicious or fail to recognize actual threats. The vulnerability is particularly concerning because it operates at the core security protection layer of the BIG-IP system, potentially allowing attackers to bypass multiple security controls simultaneously.
From an operational perspective, this vulnerability creates significant risk for organizations relying on F5 BIG-IP ASM for web application protection. The failure of BADOS protection means that attackers can potentially execute sustained denial of service attacks that would normally be detected and mitigated by the system's behavioral analysis capabilities. This could result in complete service disruption, performance degradation, or unauthorized access to protected applications. The impact extends beyond simple availability issues as the vulnerability may also allow attackers to exhaust system resources, potentially leading to system crashes or requiring manual intervention to restore normal operations. Organizations may experience extended downtime while investigating and resolving the attack conditions, resulting in both operational and financial consequences.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the T1498 tactic for Network Denial of Service, where the failure of protection mechanisms aligns with techniques that exploit system weaknesses to maintain persistent access or cause service disruption. The vulnerability also relates to CWE-20, which addresses "Improper Input Validation," as the system's failure to properly validate traffic patterns during behavioral analysis constitutes a validation flaw. Organizations should implement immediate mitigations including applying the vendor-provided security patches, implementing additional network-level controls, and monitoring for unusual traffic patterns that may indicate exploitation attempts. The recommended approach involves upgrading to F5 BIG-IP ASM versions that contain the corrected behavioral analysis algorithms and establishing enhanced logging and monitoring procedures to detect potential exploitation attempts.