:warning: THIS IS A EXPERIMENTAL DETECTION

This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

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Description

This particular behavior is typically executed when an adversaries or malware gains access to an endpoint and beings to perform execution and to evade detections. Usually, a batch (.bat) will be executed and multiple registry and scheduled task modifications will occur. During triage, review parallel processes and identify any further file modifications. Endpoint should be isolated.

  • Type: TTP
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Registry
  • Last Updated: 2021-12-08
  • Author: Bhavin Patel, Splunk
  • ID: aa4f115a-3024-11ec-9987-acde48001122

Annotations

ATT&CK

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
6
| from read_ssa_enriched_events() 
| eval timestamp=parse_long(ucast(map_get(input_event,"_time"), "string", null)), registry_path=lower(ucast(map_get(input_event, "registry_path"), "string", null)), registry_key_name=lower(ucast(map_get(input_event, "registry_key_name"), "string", null)), registry_value_data=ucast(map_get(input_event, "registry_value_data"), "string", null), process_guid=ucast(map_get(input_event, "process_guid"), "string", null), event_id=ucast(map_get(input_event, "event_id"), "string", null) 
| where like(registry_path, "%\\Policies\\Microsoft\\Windows Defender%") AND registry_key_name="DisableAntiVirus" AND registry_value_data="(0x00000001)" 
| eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"), "string", null)), body=create_map( [ "event_id", event_id, "registry_path", registry_path, "registry_key_name", registry_key_name, "process_guid", process_guid,"registry_value_data",registry_value_data]) 
| into write_ssa_detected_events();

Macros

The SPL above uses the following Macros:

:information_source: disable_defender_antivirus_registry_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Registry.dest
  • Registry.user
  • Registry.registry_value_name
  • Registry.registry_key_name
  • Registry.registry_path
  • Registry.registry_value_data

How To Implement

To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

Admin or user may choose to disable windows defender product

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Modified/added/deleted registry entry $registry_path$ in $dest$

: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