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Description

This analytic will detect a suspicious process commandline related to windows defender exclusion feature. This command is abused by adversaries, malware author and red teams to bypassed Windows Defender Anti-Virus product by excluding folder path, file path, process, extensions and etc. from its real time or schedule scan to execute their malicious code. This is a good indicator for defense evasion and to look further for events after this behavior.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-11-25
  • Author: Teoderick Contreras, Splunk
  • ID: 907ac95c-4dd9-11ec-ba2c-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1562.001 Disable or Modify Tools Defense Evasion
T1562 Impair Defenses Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`powershell` EventCode=4104 (Message = "*Add-MpPreference *" OR Message = "*Set-MpPreference *") AND Message = "*-exclusion*" 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `powershell_windows_defender_exclusion_commands_filter`

Macros

The SPL above uses the following Macros:

:information_source: powershell_windows_defender_exclusion_commands_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
  • EventCode
  • Message
  • ComputerName
  • User

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

admin or user may choose to use this windows features.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
64.0 80 80 exclusion command $Message$ executed on $ComputerName$

: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