Someone's attacking a critical 0-day RCE in F5 BIG-IP APM

CVE-2023-46747 is a critical authentication bypass (CVSS 9.8) in the F5 BIG-IP Configuration Utility (TMUI) affecting most BIG-IP modules, including LTM, APM, DNS, AWAF, AFM, ASM, and SSL Orchestrator. By sending undisclosed, specially crafted requests to the TMUI, an attacker with network access to the BIG-IP management port and/or self IP addresses bypasses authentication and can execute arbitrary system commands on the system. No privileges or user interaction are required, and successful exploitation effectively yields full control of the affected BIG-IP deployment. Any organization running vulnerable BIG-IP software is exposed, particularly enterprises, service providers, and government agencies whose management interface or self IPs are reachable. The flaw is being actively exploited: it was added to CISA KEV on 2023-10-31 with known ransomware use, public PoC code exists, and reporting links it to Chinese nation-state actors targeting defense and government networks.

Do: Upgrade all affected BIG-IP systems to the fixed releases identified in F5 advisory K13763 (17.1.0.1, 16.1.4, 15.1.9, 14.1.5.5, or 13.1.5.1 depending on the train, or later); the CISA KEV listing makes remediation mandatory for federal agencies. As an interim mitigation, restrict network access to the TMUI management port and self IP addresses and apply F5's documented mitigation guidance. Given active nation-state and ransomware exploitation, also audit appliances for indicators of compromise such as unexpected accounts, scheduled tasks, and configuration changes.

F5 BIG-IP Access Policy Manager (APM) contains a heap-based buffer overflow (CWE-122) that is reachable when a virtual server has both an APM access policy and an OAuth profile configured. An unauthenticated remote attacker can send specifically crafted malicious traffic to such a virtual server and achieve remote code execution on the BIG-IP system, which fully compromises the confidentiality, integrity, and availability of the traffic-management device. Systems running in Appliance mode are also vulnerable, and because this is a data plane flaw, the exposure is at the virtual server itself rather than the management control plane. The vulnerability is rated critical (CVSS 4.0: 9.3) with no privileges or user interaction required. No public proof-of-concept or confirmed in-the-wild exploitation is known, and F5 has not evaluated software versions that have reached End of Technical Support.

Do: Inventory virtual servers with an APM access policy plus an OAuth profile and prioritize patching those first, applying the fixed release identified in F5's advisory (EoTS versions must be upgraded to a supported release to receive a fix). Until patched, remove the OAuth profile from internet-facing virtual servers where feasible or restrict access to the virtual server so untrusted sources cannot reach the APM listener. Monitor BIG-IP logs for anomalous traffic to APM-enabled virtual servers, since exploitation would not touch the management plane.