CVE-2019-19151 in BIG-IP
Summary
by MITRE
On BIG-IP versions 15.0.0-15.1.0, 14.0.0-14.1.2.3, 13.1.0-13.1.3.2, 12.1.0-12.1.5, and 11.5.2-11.6.5.1, BIG-IQ versions 7.0.0, 6.0.0-6.1.0, and 5.0.0-5.4.0, iWorkflow version 2.3.0, and Enterprise Manager version 3.1.1, authenticated users granted TMOS Shell (tmsh) privileges are able access objects on the file system which would normally be disallowed by tmsh restrictions. This allows for authenticated, low privileged attackers to access objects on the file system which would not normally be allowed.
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Analysis
by VulDB Data Team • 03/16/2024
This vulnerability represents a critical privilege escalation issue affecting F5 BIG-IP and related systems where authenticated users with TMOS Shell (tmsh) privileges can bypass file system access controls that normally restrict their permissions. The flaw exists across multiple major versions of BIG-IP, BIG-IQ, iWorkflow, and Enterprise Manager platforms, indicating a widespread impact throughout F5's product ecosystem. The vulnerability specifically targets the tmsh command interface which serves as the primary administrative shell for F5 devices, making it a particularly dangerous issue for organizations relying on these systems for network security.
The technical implementation of this vulnerability stems from insufficient input validation and access control enforcement within the tmsh interface. When authenticated users execute commands through tmsh, the system should enforce strict boundaries on file system access based on user privileges and role-based restrictions. However, this vulnerability allows attackers to craft specific tmsh commands or sequences that circumvent these security controls, enabling access to sensitive system files, configuration data, and other restricted resources that should normally be protected from low-privileged users. This represents a direct violation of the principle of least privilege and demonstrates a failure in the authorization mechanism that should govern access to system resources.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it provides attackers with the ability to potentially extract sensitive information, modify critical system components, or establish persistent access to the affected platforms. Attackers who successfully exploit this vulnerability could access system configuration files containing encryption keys, certificate information, and other sensitive data that could compromise the entire security infrastructure. The vulnerability is particularly concerning because it affects authenticated users who already possess legitimate administrative privileges, meaning that attackers would not need to perform additional authentication attacks to exploit this issue. This makes the attack surface significantly larger and the potential damage more severe, as the attacker can leverage existing legitimate access to escalate their privileges and gain access to restricted resources.
Organizations should immediately implement mitigations including applying the latest security patches provided by F5, which typically involve updating the tmsh interface to properly enforce access controls and validate user inputs. Network segmentation and monitoring should be enhanced to detect unusual tmsh activity patterns that might indicate exploitation attempts. Additionally, organizations should review and tighten their access control policies, ensuring that only essential personnel have tmsh privileges and that these privileges are granted based on strict need-to-know principles. This vulnerability aligns with CWE-285 (Improper Authorization) and could be categorized under ATT&CK technique T1078 (Valid Accounts) and T1566 (Phishing) if exploited through initial compromise, while also representing a privilege escalation vector that could enable further attacks through lateral movement and persistence techniques. The widespread affected versions indicate that organizations should prioritize patch management and security assessments across their entire F5 infrastructure to ensure comprehensive protection against this and related vulnerabilities.