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Remote System Discovery with Adsisearcher

Author
Mauricio Velazco, Splunk
Source
upstream

The following analytic detects the use of the [Adsisearcher] type accelerator in PowerShell scripts to query Active Directory for domain computers. It leverages PowerShell Script Block Logging (EventCode=4104) to identify specific script blocks containing adsisearcher and objectcategory=computer with methods like findAll() or findOne(). This activity is significant as it may indicate an attempt by adversaries or Red Teams to perform Active Directory discovery and gain situational awareness. If confirmed malicious, this could lead to further reconnaissance and potential lateral movement within the network.

MITRE ATT&CK coverage

TacticTechniques
DiscoveryT1018 Remote System Discovery

Event coverage

ProviderEvent IDTitle
PowerShell4104Creating Scriptblock text (MessageNumber of MessageTotal).

Stages and Predicates

Stage 1: search

search EventCode=4104 ScriptBlockText="*adsisearcher*" ScriptBlockText="*objectcategory=computer*" ScriptBlockText IN ("*findAll()*", "*findOne()*")

Stage 2: fillnull

fillnull

Stage 3: stats

stats BY dest, signature, signature_id, user_id, vendor_product, EventID, Guid, Opcode, Name, Path, ProcessID, ScriptBlockId, ScriptBlockText

Stage 4: search

search

Stage 5: search

search `macro`

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
EventCodeeq
  • 4104 corpus 108 (splunk 108)
ScriptBlockTexteq
  • "*adsisearcher*"
  • "*objectcategory=computer*"
ScriptBlockTextin
  • "*findAll()*"
  • "*findOne()*"

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.