GitHub Repo

Detection: Windows Downdate Registry Activity

Updated Date: 2026-04-13 ID: d984fca1-ba3a-4f89-aa58-800e235fdf53 Author: Raven Tait, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

Detects the setting of a pending.xml file associated with the Windows Downdate attack which forces a Windows downgrade to enable exploitation. Looks for uses of a pending.xml outside of typical locations.

 1`sysmon`
 2EventID IN (
 3    12,
 4    13,
 5    14
 6)
 7TargetObject IN (
 8    "*PoqexecCmdline",
 9    "*COMPONENTS\\PendingXmlIdentifier"
10)
11NOT ProcessPath="*:\\Windows\\WinSxS\\*"
12
13
14| fillnull
15
16| stats count min(_time) as firstTime
17              max(_time) as lastTime
18
19  by EventID TargetObject ProcessPath Computer action process_guid process_id
20     registry_hive registry_path registry_key_name registry_value_data registry_value_name
21     status user vendor_product
22
23
24| rename Computer as dest
25
26| `security_content_ctime(firstTime)`
27
28| `security_content_ctime(lastTime)`
29
30| `windows_downdate_registry_activity_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 12 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 13 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 14 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_downdate_registry_activity_filter search *
windows_downdate_registry_activity_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1112 Modify Registry Defense Impairment
T1689 Downgrade Attack Persistence
Exploitation
Installation
DE.AE
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Legitimate system updates or rollback processes may create or modify pending.xml files in non-standard locations. Verify with IT change management to reduce false alerts.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Potential Downdate registry activity observed on $dest$ via $TargetObject$.

Risk Object Risk Object Type Risk Score Threat Objects
dest system 50 No Threat Objects

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

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: GitHub | Version: 1