Windows Modify Registry UpdateServiceUrlAlternate

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects a suspicious modification to the Windows Update configuration registry key, specifically targeting the UpdateServiceUrlAlternate setting. It leverages data from the Endpoint.Registry datamodel to identify changes to this registry path. This activity is significant because adversaries, including malware like RedLine Stealer, exploit this technique to bypass detection and deploy additional payloads. If confirmed malicious, this modification could allow attackers to redirect update services, potentially leading to the execution of malicious code, further system compromise, and persistent evasion of security defenses.

name: Windows Modify Registry UpdateServiceUrlAlternate
id: ca4e94fb-7969-4d63-8630-3625809a1f70
version: 11
creation_date: '2023-04-26'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects a suspicious modification to the Windows Update configuration registry key, specifically targeting the UpdateServiceUrlAlternate setting. It leverages data from the Endpoint.Registry datamodel to identify changes to this registry path. This activity is significant because adversaries, including malware like RedLine Stealer, exploit this technique to bypass detection and deploy additional payloads. If confirmed malicious, this modification could allow attackers to redirect update services, potentially leading to the execution of malicious code, further system compromise, and persistent evasion of security defenses.
data_source:
    - Sysmon EventID 13
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path="*\\SOFTWARE\\Policies\\Microsoft\\Windows\\WindowsUpdate\\UpdateServiceUrlAlternate" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product | `drop_dm_object_name(Registry)` | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `windows_modify_registry_updateserviceurlalternate_filter`'
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` datamodel in the `Processes` node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
known_false_positives: Administrators may enable or disable this feature that may cause some false positive.
references:
    - https://learn.microsoft.com/de-de/security-updates/windowsupdateservices/18127499
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A registry modification in Windows auto update configuration on $dest$
analytic_story:
    - RedLine Stealer
asset_type: Endpoint
mitre_attack_id:
    - T1112
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/redline/modify_registry/sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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