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Description

This analytic is to detect an application try to connect and create ADSI Object to do LDAP query. Every time an application connects to the directory and attempts to create an ADSI object, the Active Directory Schema is checked for changes. If it has changed since the last connection, the schema is downloaded and stored in a cache on the local computer either in %LOCALAPPDATA%\Microsoft\Windows\SchCache or %systemroot%\SchCache. We found this a good anomaly use case to detect suspicious application like blackmatter ransomware that use ADS object api to execute ldap query. having a good list of ldap or normal AD query tool used within the network is a good start to reduce the noise.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-09-07
  • Author: Teoderick Contreras, Splunk
  • ID: 991eb510-0fc6-11ec-82d3-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1087.002 Domain Account Discovery
T1087 Account Discovery Discovery
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`sysmon` EventCode=11  TargetFilename = "*\\Windows\\SchCache\\*" TargetFilename = "*.sch*" NOT (Image IN ("*\\Windows\\system32\\mmc.exe")) 
|stats count min(_time) as firstTime max(_time) as lastTime by Image TargetFilename EventCode process_id  process_name Computer 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `schcache_change_by_app_connect_and_create_adsi_object_filter`

Macros

The SPL above uses the following Macros:

Note that schcache_change_by_app_connect_and_create_adsi_object_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
  • TargetFilename
  • EventCode
  • process_id
  • process_name
  • Computer

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line 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

normal application like mmc.exe and other ldap query tool may trigger this detections.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
25.0 50 50 process $Image$ create a file $TargetFilename$ in host $Computer$

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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