CVE-2016-5024 in BIG-IP
Summary
by MITRE
Virtual servers in F5 BIG-IP systems 11.6.1 before 11.6.1 HF1 and 12.1.x before 12.1.2, when configured to parse RADIUS messages via an iRule, allow remote attackers to cause a denial of service (Traffic Management Microkernel restart) via crafted network traffic.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-5024 affects F5 BIG-IP systems operating in virtual server configurations that process RADIUS messages through iRules. This flaw exists in specific versions of the BIG-IP platform including 11.6.1 before the first hotfix and 12.1.x versions before 12.1.2. The issue represents a critical security weakness that enables remote attackers to disrupt service availability by exploiting a flaw in how the system handles RADIUS message parsing. The vulnerability specifically targets the Traffic Management Microkernel component of the BIG-IP system, which serves as the core processing engine for traffic management functions.
The technical mechanism behind this vulnerability involves a buffer overflow or memory corruption issue that occurs when the system processes malformed RADIUS packets through iRule configurations. When an attacker crafts specific network traffic that conforms to RADIUS protocol specifications but contains maliciously constructed data fields, the parsing logic within the Traffic Management Microkernel fails to properly validate or handle these inputs. This processing failure results in an abrupt system restart of the microkernel component, effectively causing the virtual server to become unavailable and disrupting all traffic management services. The flaw demonstrates characteristics consistent with CWE-121, heap-based buffer overflow, where insufficient bounds checking allows attackers to overwrite memory regions and trigger system instability.
The operational impact of CVE-2016-5024 extends beyond simple service disruption to encompass potential business continuity risks for organizations relying on F5 BIG-IP systems for critical network infrastructure. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring authentication or physical access to the system. This characteristic aligns with ATT&CK technique T1499.004, which involves network disruption attacks that can be executed remotely. The vulnerability affects all virtual server configurations that utilize iRules for RADIUS message processing, potentially impacting organizations with extensive load balancing deployments, authentication services, or network access control implementations that depend on RADIUS protocols.
Organizations affected by this vulnerability should immediately implement mitigation strategies focusing on both immediate protection and long-term remediation. The primary recommended action involves applying the vendor-provided hotfixes and software updates that address the specific memory handling issues in the Traffic Management Microkernel. Additionally, network administrators should consider implementing network segmentation controls to limit exposure of affected systems to untrusted networks, and should disable RADIUS processing through iRules if the functionality is not critical to operations. Security monitoring should be enhanced to detect anomalous RADIUS traffic patterns that might indicate exploitation attempts, and incident response procedures should be updated to address potential system restart events that could indicate successful exploitation of this vulnerability. The remediation process should also include comprehensive testing of updated systems to ensure that the patch does not introduce compatibility issues with existing iRule configurations or network services.