LoFP LoFP / false positives should be limited to as this is strict to active exploitation. reduce noise by filtering to f5 devices with tmui enabled or filter data as needed.

Techniques

Sample rules

F5 TMUI Authentication Bypass

Description

The following analytic is designed to detect attempts to exploit the CVE-2023-46747 vulnerability, a critical authentication bypass flaw in F5 BIG-IP that can lead to unauthenticated remote code execution (RCE). This vulnerability specifically affects the BIG-IP Configuration utility (TMUI) and has been assigned a high severity CVSSv3 score of 9.8. The analytic identifies this behavior by monitoring for a specific URI path - “/mgmt/tm/auth/user/”, with the PATCH method and 200 status. Additional URI’s will occur around the same time include “/mgmt/shared/authn/login” and “/tmui/login.jsp”, which are associated with the exploitation of this vulnerability. This behavior is significant for a Security Operations Center (SOC) as it indicates an attempt to bypass authentication mechanisms, potentially leading to unauthorized access and control over the system. If a true positive is identified, it suggests that an attacker is attempting to exploit a known vulnerability to gain unauthorized access and execute arbitrary code, which could lead to data theft, system disruption, or further malicious activities within the network.

Detection logic


| tstats count min(_time) as firstTime max(_time) as lastTime from datamodel=Web where Web.url IN ("*/mgmt/tm/auth/user/*") Web.http_method=PATCH Web.status=200 by Web.http_user_agent, Web.status Web.http_method, Web.url, Web.url_length, Web.src, Web.dest, sourcetype 
| `drop_dm_object_name("Web")` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
| `f5_tmui_authentication_bypass_filter`