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Detection rules › Sigma

DirectorySearcher Powershell Exploitation

Status
test
Severity
medium
Log source
product windows, category ps_script
Author
frack113
Source
github.com/SigmaHQ/sigma

Enumerates Active Directory to determine computers that are joined to the domain

MITRE ATT&CK coverage

TacticTechniques
DiscoveryT1018 Remote System Discovery

Event coverage

ProviderEventTitle
PowerShellEvent ID 4104Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body yaml

title: DirectorySearcher Powershell Exploitation
id: 1f6399cf-2c80-4924-ace1-6fcff3393480
status: test
description: Enumerates Active Directory to determine computers that are joined to the domain
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1018/T1018.md#atomic-test-15---enumerate-domain-computers-within-active-directory-using-directorysearcher
author: frack113
date: 2022-02-12
tags:
    - attack.discovery
    - attack.t1018
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - 'New-Object '
            - 'System.DirectoryServices.DirectorySearcher'
            - '.PropertiesToLoad.Add'
            - '.findall()'
            - 'Properties.name'
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ScriptBlockText|contains|all:
        - 'New-Object '
        - 'System.DirectoryServices.DirectorySearcher'
        - '.PropertiesToLoad.Add'
        - '.findall()'
        - 'Properties.name'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
ScriptBlockTextmatch
  • .PropertiesToLoad.Add
  • .findall() corpus 2 (sigma 1, splunk 1)
  • New-Object corpus 2 (sigma 2)
  • Properties.name
  • System.DirectoryServices.DirectorySearcher