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Description

This search is to detect a suspicious loaded unsigned dll by MMC.exe application. This technique is commonly seen in attacker that tries to bypassed UAC feature or gain privilege escalation. This is done by modifying some CLSID registry that will trigger the mmc.exe to load the dll path

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-07-12
  • Author: Teoderick Contreras, Splunk
  • ID: 7f04349c-e30d-11eb-bc7f-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1548.002 Bypass User Account Control Defense Evasion, Privilege Escalation
T1548 Abuse Elevation Control Mechanism Defense Evasion, Privilege Escalation
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`sysmon` EventCode=7  ImageLoaded = "*.dll" Image = "*\\mmc.exe" Signed=false Company != "Microsoft Corporation" 
| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded Signed ProcessId OriginalFileName Computer EventCode Company 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `uac_bypass_mmc_load_unsigned_dll_filter`

Macros

The SPL above uses the following Macros:

Note that uac_bypass_mmc_load_unsigned_dll_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
  • Signed
  • ProcessId
  • OriginalFileName
  • Computer
  • EventCode
  • Company

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

unknown. all of the dll loaded by mmc.exe is microsoft signed dll.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
63.0 70 90 Suspicious unsigned $ImageLoaded$ loaded by $Image$ on endpoint $Computer$ with EventCode $EventCode$

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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