CVE-2018-5516 in BIG-IP
Summary
by MITRE
On F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.2, or 11.2.1-11.6.3.1, Enterprise Manager 3.1.1, BIG-IQ Centralized Management 5.0.0-5.4.0 or 4.6.0, BIG-IQ Cloud and Orchestration 1.0.0, or F5 iWorkflow 2.0.2-2.3.0, authenticated users granted TMOS Shell (tmsh) access can access objects on the file system which would normally be disallowed by tmsh restrictions. This allows for authenticated, low privileged attackers to exfiltrate objects on the file system which should not be allowed.
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Analysis
by VulDB Data Team • 03/08/2023
The vulnerability identified as CVE-2018-5516 represents a critical privilege escalation and information disclosure flaw within F5 BIG-IP systems across multiple versions including 13.0.0-13.1.0.5, 12.1.0-12.1.2, and 11.2.1-11.6.3.1. This issue affects Enterprise Manager 3.1.1, BIG-IQ Centralized Management 5.0.0-5.4.0 or 4.6.0, BIG-IQ Cloud and Orchestration 1.0.0, and F5 iWorkflow 2.0.2-2.3.0 components. The flaw specifically targets the TMOS Shell (tmsh) access controls that are designed to restrict file system interactions to prevent unauthorized access to sensitive system components. The vulnerability stems from insufficient validation of file system access permissions within the tmsh interface, allowing authenticated users to bypass established security boundaries. This represents a direct violation of the principle of least privilege and demonstrates a failure in access control mechanisms that should prevent users from accessing restricted file system objects.
The technical exploitation of this vulnerability occurs when authenticated users with TMOS Shell access attempt to interact with file system objects that should normally be restricted by tmsh access controls. The flaw allows attackers to navigate to directories and access files that contain sensitive information such as configuration files, cryptographic keys, and system credentials. This unauthorized access can be achieved through specific tmsh commands that bypass the intended security restrictions, enabling attackers to read and exfiltrate sensitive data from the file system. The vulnerability specifically targets the tmsh command execution environment where proper access controls should prevent users from accessing system files outside their designated scope, yet the implementation fails to enforce these restrictions properly.
The operational impact of CVE-2018-5516 extends beyond simple information disclosure to encompass potential system compromise and data exfiltration capabilities. Attackers can leverage this vulnerability to extract sensitive configuration data, system credentials, and cryptographic materials that could be used for further attacks within the network infrastructure. The ability to access restricted file system objects provides attackers with valuable insights into system architecture and security configurations, potentially enabling more sophisticated attacks such as lateral movement, privilege escalation, or even complete system compromise. This vulnerability particularly affects enterprise environments where F5 BIG-IP appliances serve as critical network infrastructure components, making the potential impact substantial for organizations relying on these systems for application delivery and network security.
Organizations should implement immediate mitigations including applying the latest security patches from F5, which address the tmsh access control bypass through proper validation of file system permissions. Network segmentation and monitoring should be enhanced to detect unauthorized access attempts to critical system components, with particular attention to tmsh command execution patterns. Access controls should be reviewed and strengthened to ensure that only authorized personnel have TMOS Shell access, with additional logging implemented for tmsh command activities. The vulnerability aligns with CWE-284 Access Control Issues, specifically concerning insufficient access control validation, and represents a technique that could be mapped to ATT&CK tactics including privilege escalation and credential access. Security teams should also consider implementing automated monitoring solutions that can detect anomalous file system access patterns and alert on potential exploitation attempts. Regular security assessments and penetration testing should be conducted to verify the effectiveness of implemented controls and identify any additional vulnerabilities within the F5 BIG-IP environment.