: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 analytic is built to detect a suspicious modification of the Windows registry related to UAC bypass. This technique is to modify the registry in this detection, create a registry value with the path of the payload and run WSreset.exe to bypass User Account Control.

  • Type: Anomaly
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Registry
  • Last Updated: 2022-02-18
  • Author: Lou Stella, Splunk
  • ID: 3118f0c2-90d9-11ec-b833-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1548.002 Bypass User Account Control Privilege Escalation, Defense Evasion
T1548 Abuse Elevation Control Mechanism Privilege Escalation, Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 14
CVE
1
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3
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| from read_ssa_enriched_events() 
| where "Endpoint_Registry" IN (_datamodels) 
| 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_hive=lower(ucast(map_get(input_event, "registry_hive"), "string", null)), registry_value_name=lower(ucast(map_get(input_event, "registry_value_name"), "string", null)), registry_key_name=lower(ucast(map_get(input_event, "registry_key_name"), "string", null)), registry_value_type=lower(ucast(map_get(input_event, "registry_value_type"), "string", null)), registry_value_data=lower(ucast(map_get(input_event, "registry_value_data"), "string", null)), process_guid=lower(ucast(map_get(input_event, "process_guid"), "string", null)) 
| where registry_path IS NOT NULL AND registry_value_name IS NOT NULL and like (registry_path, "%\\\\AppX82a6gwre4fdg3bt635tn5ctqjf8msdd2\\\\Shell\\\\open\\\\command%") AND (registry_value_name="(Default)" OR registry_value_name="DelegateExecute") 
| 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)) 
| eval body=create_map(["registry_path", registry_path, "registry_hive", registry_hive, "registry_value_name", registry_value_name, "registry_key_name", registry_key_name, "registry_value_type", registry_value_type, "registry_value_data", registry_value_data, "process_guid", process_guid]) 
| into write_ssa_detected_events(); 

Macros

The SPL above uses the following Macros:

:information_source: windows_wsreset_uac_bypass_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_path
  • registry_hive
  • registry_value_name
  • registry_key_name
  • registry_value_type
  • registry_value_data
  • process_guid

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_Registry datamodel.

Known False Positives

Unknown at this point in time.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
63.0 70 90 tbd

: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

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