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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.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Web
  • Last Updated: 2023-10-30
  • Author: Michael Haag, Splunk
  • ID: 88bf127c-613e-4579-99e4-c4d4b02f3840

Annotations

ATT&CK
Kill Chain Phase
NIST
  • DE.CM
CIS20
  • CIS 10
CVE
ID Summary CVSS
CVE-2023-46747    

Undisclosed requests may bypass configuration utility authentication, allowing an attacker with network access to the BIG-IP system through the management port and/or self IP addresses to execute arbitrary system commands.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated

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| 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`

Macros

The SPL above uses the following Macros:

:information_source: f5_tmui_authentication_bypass_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • Web.http_user_agent
  • Web.status
  • Web.http_method
  • Web.url
  • Web.url_length
  • Web.src
  • Web.dest
  • sourcetype

How To Implement

To successfully implement this search you need to be ingesting information on Web traffic that include fields relevant for traffic into the Web datamodel.

Known False Positives

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
90.0 100 90 Potential CVE-2023-46747 F5 TMUI Authentication Bypass may be occurring against $dest$ from $src$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 1