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Description

This analytic detects a potential process using COM Object like CMLUA or CMSTPLUA to bypass UAC. This technique has been used by ransomware adversaries to gain administrative privileges to its running process.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-05-13
  • Author: Teoderick Contreras, Splunk
  • ID: f87b5062-b405-11eb-a889-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1218 Signed Binary Proxy Execution Defense Evasion
T1218.003 CMSTP Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`sysmon` EventCode=7  ImageLoaded IN ("*\\CMLUA.dll", "*\\CMSTPLUA.dll", "*\\CMLUAUTIL.dll") NOT(process_name IN("CMSTP.exe", "CMMGR32.exe")) NOT(Image IN("*\\windows\\*", "*\\program files*")) 
| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded process_name Computer EventCode Signed ProcessId 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `cmlua_or_cmstplua_uac_bypass_filter`

Macros

The SPL above uses the following Macros:

Note that cmlua_or_cmstplua_uac_bypass_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • Image
  • ImageLoaded
  • process_name
  • Computer
  • EventCode
  • Signed
  • ProcessId

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and imageloaded executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

Legitimate windows application that are not on the list loading this dll. Filter as needed.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
80.0 80 100 The following module $ImageLoaded$ was loaded by a non-standard application on endpoint $Computer$ by user $user$.

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

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