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Description

This analytic is developed to detect suspicious registry modifications that disable Remote Desktop Protocol (RDP) by altering the "fDenyTSConnections" key. Changing this key's value to 1 prevents remote connections, which can disrupt remote management and access. Such modifications could indicate an attempt to hinder remote administration or isolate the system from remote intervention, potentially signifying malicious activity.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-06-19
  • Author: Teoderick Contreras, Splunk
  • ID: 11ed764f-eb9c-4be7-bdad-2209b9d33ee1

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1112 Modify Registry Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where Registry.registry_path= "*\\Control\\Terminal Server\\fDenyTSConnections*" Registry.registry_value_data="0x00000001" by Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.dest 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_modify_registry_disable_rdp_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_modify_registry_disable_rdp_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.registry_path
  • Registry.registry_key_name
  • Registry.registry_value_name
  • Registry.registry_key_name
  • Registry.user
  • Registry.dest
  • Registry.action
  • Registry.registry_value_data
  • Registry.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 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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 A registry modification in Windows RDP registry settings on $dest$

: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

source | version: 1