CVE-2019-6641 in BIG-IP
Summary
by MITRE
On BIG-IP 12.1.0-12.1.4.1, undisclosed requests can cause iControl REST processes to crash. The attack can only come from an authenticated user; all roles are capable of performing the attack. Unauthenticated users cannot perform this attack.
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Analysis
by VulDB Data Team • 10/17/2023
The vulnerability identified as CVE-2019-6641 represents a critical denial of service weakness within F5 BIG-IP systems running specific software versions. This flaw exists within the iControl REST API processing mechanisms and affects versions 12.1.0 through 12.1.4.1 of the BIG-IP platform. The vulnerability operates through a mechanism that allows authenticated users to submit specially crafted requests that trigger process crashes within the iControl REST framework, effectively disrupting normal system operations and service availability. The attack vector specifically targets the REST API endpoints that handle configuration and management operations, making it particularly dangerous for administrators who rely on these interfaces for system maintenance and monitoring.
The technical nature of this vulnerability stems from improper input validation and error handling within the iControl REST processes that manage authentication and authorization workflows. When an authenticated user submits maliciously constructed requests to the REST API, the system fails to properly sanitize or validate the incoming data, leading to memory corruption or resource exhaustion that ultimately causes the targeted processes to terminate unexpectedly. This behavior aligns with CWE-20, which describes improper input validation as a fundamental weakness in software security design. The vulnerability's exploitation requires authentication credentials, indicating that it operates within the bounds of legitimate administrative access rather than representing an initial compromise vector, though it can be leveraged by malicious insiders or compromised accounts.
The operational impact of CVE-2019-6641 extends beyond simple service disruption to potentially compromise the overall reliability and availability of critical network infrastructure. When iControl REST processes crash, administrators lose access to essential configuration management capabilities, forcing them to rely on alternative access methods such as command line interfaces or physical console access. This situation creates significant operational challenges during emergency response scenarios where rapid configuration changes or troubleshooting are required. The vulnerability affects all user roles within the BIG-IP system, meaning that even standard users with limited privileges can potentially cause system-wide disruptions, creating a risk that extends beyond traditional privilege-based security models. Organizations may experience extended downtime while system processes restart and recover, potentially impacting business continuity and customer service availability.
Mitigation strategies for this vulnerability should focus on immediate patching and access control measures. F5 released security patches for affected versions that address the underlying input validation issues and improve error handling within the iControl REST framework. Organizations should prioritize applying these patches to all affected systems while maintaining strict monitoring of authentication logs for suspicious activity patterns. Network segmentation and role-based access controls can help limit the potential impact of compromised accounts by reducing the scope of access that authenticated users can exercise. The vulnerability's classification under ATT&CK technique T1489 suggests that defenders should implement monitoring for process termination events and API access patterns that might indicate exploitation attempts. Additionally, implementing comprehensive backup and recovery procedures ensures that system administrators can quickly restore services when disruptions occur, while maintaining audit trails helps identify the source and scope of any exploitation attempts.