F5 BIG-IP Exposed to Kerberos KDC Spoofing Vulnerability
On April 28, 2021, cybersecurity researchers revealed a significant bypass vulnerability (CVE-2021-23008) affecting the Kerberos Key Distribution Center (KDC) security feature in F5 BIG-IP application delivery services. According to Silverfort researchers Yaron Kassner and Rotem Zach, the KDC Spoofing vulnerability enables attackers to circumvent Kerberos authentication to the Big-IP Access Policy Manager (APM), allowing unauthorized access to sensitive resources and, in some instances, the Big-IP admin console. Following this disclosure, F5 Networks issued patches to rectify the vulnerability (CVE-2021-23008, CVSS score 8.1), which are available in BIG-IP APM versions 12.1.6, 13.1.4, 14.1.4, and 15.1.3. A similar patch for version 16.x is anticipated in the future. Customers using version 16.x are advised to consult the security advisory for exposure assessment and mitigation details.