Detection rules › Splunk
Windows Modify Registry USeWuServer
The following analytic detects a suspicious modification to the Windows Update configuration registry key "UseWUServer." It leverages data from the Endpoint.Registry data model to identify changes where the registry value is set to "0x00000001." This activity is significant because it is commonly used by adversaries, including malware like RedLine Stealer, to bypass detection mechanisms and potentially exploit zero-day vulnerabilities. If confirmed malicious, this modification could allow attackers to evade defenses, persist on the target host, and deploy additional malicious payloads.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1112 Modify Registry |
| Defense Impairment | T1112 Modify Registry |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 13 | RegistryEvent (Value Set) |
Rule body splunk
name: Windows Modify Registry USeWuServer
id: c427bafb-0b2c-4b18-ad85-c03c6fed9e75
version: 9
creation_date: '2023-04-26'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Hunting
description: The following analytic detects a suspicious modification to the Windows Update configuration registry key "UseWUServer." It leverages data from the Endpoint.Registry data model to identify changes where the registry value is set to "0x00000001." This activity is significant because it is commonly used by adversaries, including malware like RedLine Stealer, to bypass detection mechanisms and potentially exploit zero-day vulnerabilities. If confirmed malicious, this modification could allow attackers to evade defenses, persist on the target host, and deploy additional malicious payloads.
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\\AU\\UseWUServer" AND Registry.registry_value_data="0x00000001" 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_usewuserver_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
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
Stages and Predicates
Stage 1: tstats
| 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\\AU\\UseWUServer" AND Registry.registry_value_data="0x00000001" 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
Stage 2: search
| `drop_dm_object_name(Registry)`
Stage 3: search
| `security_content_ctime(lastTime)`
Stage 4: search
| `security_content_ctime(firstTime)`
Stage 5: search
| `windows_modify_registry_usewuserver_filter`
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.
| Field | Kind | Values |
|---|---|---|
Registry.registry_path | eq |
|
Registry.registry_value_data | eq |
|