CVE-2019-6616 in BIG-IP
Summary
by MITRE
On BIG-IP 14.0.0-14.1.0.1, 13.0.0-13.1.1.4, 12.1.0-12.1.4, 11.6.1-11.6.3.4, and 11.5.2-11.5.8, administrative users with TMSH access can overwrite critical system files on BIG-IP which can result in bypass of whitelist / blacklist restrictions enforced by appliance mode.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-6616 represents a critical privilege escalation flaw within F5 BIG-IP network security appliances affecting multiple software versions including 14.0.0 through 14.1.0.1, 13.0.0 through 13.1.1.4, 12.1.0 through 12.1.4, 11.6.1 through 11.6.3.4, and 11.5.2 through 11.5.8. This security weakness specifically targets administrative users who possess TMSH (Traffic Management Shell) access rights, creating a significant risk for organizations relying on these appliances for network security enforcement. The vulnerability stems from inadequate file system permissions and access controls that allow authenticated administrative users to manipulate critical system files through the TMSH interface.
The technical implementation of this flaw involves the improper handling of file system operations within the BIG-IP appliance's administrative shell environment. When administrative users execute TMSH commands, the system fails to properly validate or restrict file modification operations against protected system files that govern appliance mode restrictions. This allows attackers with sufficient privileges to overwrite critical files that control whitelist and blacklist enforcement mechanisms, effectively undermining the appliance's core security functions. The vulnerability operates at the system level rather than at the application layer, making it particularly dangerous as it can bypass fundamental security controls that are designed to prevent unauthorized network access and traffic filtering.
From an operational perspective, this vulnerability creates a severe risk for organizations deploying F5 BIG-IP appliances in production environments. The ability to overwrite critical system files means that attackers can potentially disable or modify the appliance's ability to enforce network security policies, including access control lists and traffic filtering rules. This could result in unauthorized network access, data exfiltration, or the ability to bypass security controls that protect against malicious traffic. The impact extends beyond simple privilege escalation as it fundamentally compromises the appliance's security posture, potentially allowing attackers to establish persistent access to network resources while evading detection mechanisms that rely on the appliance's filtering capabilities.
Organizations should implement immediate mitigations including restricting TMSH access to only essential administrative personnel, implementing strict access controls and monitoring for suspicious file modification activities, and applying the latest security patches provided by F5. The vulnerability aligns with CWE-276 which addresses improper file permissions and access control issues, while also mapping to ATT&CK technique T1059.001 for command and script interpreter usage. Organizations should conduct comprehensive audits of their BIG-IP appliance configurations, implement network monitoring for anomalous file system modifications, and establish incident response procedures specifically addressing this type of privilege escalation attack vector. Additionally, regular security assessments of administrative access controls and file system permissions should be performed to prevent exploitation of similar vulnerabilities in the future.