CVE-2018-5547 in BIG-IP APM Client
Summary
by MITRE
Windows Logon Integration feature of F5 BIG-IP APM client prior to version 7.1.7.1 for Windows by default uses Legacy logon mode which uses a SYSTEM account to establish network access. This feature displays a certificate user interface dialog box which contains the link to the certificate policy. By clicking on the link, unprivileged users can open additional dialog boxes and get access to the local machine windows explorer which can be used to get administrator privilege. Windows Logon Integration is vulnerable when the APM client is installed by an administrator on a user machine. Users accessing the local machine can get administrator privileges
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2018-5547 affects the Windows Logon Integration feature within F5 BIG-IP APM client versions prior to 7.1.7.1 for Windows operating systems. This security flaw resides in the authentication and authorization mechanisms of the application portal manager's client-side components, specifically targeting how the system handles user logon processes and privilege escalation. The vulnerability stems from the default configuration that employs Legacy logon mode, which operates under the SYSTEM account context to establish network access, creating an inherent security risk that can be exploited by unprivileged users.
The technical implementation of this vulnerability involves the Windows Logon Integration feature's user interface design, which presents certificate user interface dialog boxes containing links to certificate policies. When users interact with these dialog boxes by clicking on the certificate policy links, they are able to trigger additional dialog boxes that provide access to local machine windows explorer functionality. This design flaw creates an unintended code execution pathway that bypasses normal security boundaries. The vulnerability is classified under CWE-264 as "Permissions, Privileges, and Access Controls" and specifically relates to improper privilege management within the application's authentication flow.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows unprivileged users who have access to the local machine to potentially gain administrator privileges through a series of cascading dialog box interactions. The attack vector is particularly concerning because it requires minimal technical expertise to exploit, as the process involves only standard user interactions with graphical elements. This makes the vulnerability accessible to a broad range of threat actors, from casual users to more sophisticated attackers. The risk is amplified when the APM client is installed by an administrator on user machines, as this creates an environment where legitimate administrative privileges are present and accessible to users who might not otherwise possess them.
The security implications of CVE-2018-5547 align with several ATT&CK framework techniques, particularly those related to privilege escalation and credential access. The vulnerability enables adversaries to move laterally within a network by leveraging the elevated privileges that can be gained through the Windows Logon Integration feature. This represents a significant concern for enterprise environments where F5 BIG-IP APM clients are deployed, as it could allow attackers to establish persistent access to critical systems. Organizations using this software should consider the vulnerability as a potential entry point for more comprehensive attacks, especially when combined with other exploitation techniques that might be available through the elevated privileges gained.
Mitigation strategies for this vulnerability should focus on immediate remediation through the installation of F5 BIG-IP APM client version 7.1.7.1 or later, which addresses the underlying configuration and implementation issues. System administrators should also implement strict access controls and monitoring of user interactions with the APM client components, particularly focusing on unusual dialog box interactions or explorer access patterns. Network segmentation and privilege separation measures can help limit the potential impact of successful exploitation, while regular security assessments should verify that the updated configuration maintains proper security boundaries. Additionally, organizations should consider implementing endpoint detection and response solutions that can monitor for suspicious privilege escalation activities related to the APM client functionality.