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Description

This search is to detect modification of registry to bypass UAC windows feature. This technique is to add a payload dll path on .NET COR file path that will be loaded by mmc.exe as soon it was executed. This detection rely on monitoring the registry key and values in the detection area. It may happened that windows update some dll related to mmc.exe and add dll path in this registry. In this case filtering is needed.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint- Datasource: Splunk Add-on for Sysmon
  • Last Updated: 2022-02-18
  • Author: Teoderick Contreras, Splunk
  • ID: 0252ca80-e30d-11eb-8aa3-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
6
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path= "*\\Environment\\COR_PROFILER_PATH" Registry.registry_value_data = "*.dll" by Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.dest 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `net_profiler_uac_bypass_filter`

Macros

The SPL above uses the following Macros:

Note that net_profiler_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
  • Registry.registry_path
  • Registry.registry_key_name
  • Registry.registry_value_name
  • Registry.dest

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Registry node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.

Known False Positives

limited false positive. It may trigger by some windows update that will modify this registry.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
63.0 70 90 Suspicious modification of registry $registry_path$ with possible payload path $registry_value_name$ in $dest$

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: 2