GitHub Repo

Detection: Windows RDP Server Registry Entry Created

Updated Date: 2025-07-30 ID: 61f10919-c360-4e56-9cda-f1f34500cfda Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

This detection identifies the creation of registry keys under HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers, which occur when a user initiates a Remote Desktop Protocol (RDP) connection using the built-in Windows RDP client (mstsc.exe). These registry entries store information about previously connected remote hosts, including usernames and display settings. Their creation is a strong indicator that an outbound RDP session was initiated from the system. While the presence of these keys is normal during legitimate RDP use, their appearance can be used to track remote access activity, especially in environments where RDP is tightly controlled. In post-compromise scenarios, these artifacts may be created by threat actors using RDP for lateral movement or command-and-control. Monitoring the creation of these registry entries can help defenders detect initial use of RDP from a compromised host, particularly when correlated with unusual user behavior, logon patterns, or network activity.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path="*\\Microsoft\\Terminal Server Client\\Servers\\*" Registry.action != deleted 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 
3| `drop_dm_object_name(Registry)` 
4| `security_content_ctime(lastTime)` 
5| `security_content_ctime(firstTime)` 
6| `windows_rdp_server_registry_entry_created_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 13 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_rdp_server_registry_entry_created_filter search *
windows_rdp_server_registry_entry_created_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
T1021.001 Remote Desktop Protocol Lateral Movement
Exploitation
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

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 2.0 of the official Sysmon TA. https://splunkbase.splunk.com/app/5709

Known False Positives

False positives will be present, filter as needed or restrict to critical assets on the perimeter.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Risk Message goes here

Risk Object Risk Object Type Risk Score Threat Objects
dest system 10 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