Detection: Windows Remote Services Rdp Enable

Updated Date: 2024-05-13 ID: 8fbd2e88-4ea5-40b9-9217-fd0855e08cc0 Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects modifications in the Windows registry to enable Remote Desktop Protocol (RDP) on a targeted machine. It leverages data from the Endpoint.Registry datamodel, specifically monitoring changes to the "fDenyTSConnections" registry value. This activity is significant as enabling RDP via registry is uncommon and often associated with adversaries or malware attempting to gain remote access. If confirmed malicious, this could allow attackers to remotely control the compromised host, potentially leading to further exploitation and lateral movement within the network.

1
2| 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="0x00000000" by Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.dest 
3| `drop_dm_object_name(Registry)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_remote_services_rdp_enable_filter`

Data Source

Name Platform Sourcetype Source Supported App
Sysmon EventID 12 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_remote_services_rdp_enable_filter search *
windows_remote_services_rdp_enable_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
T1021 Remote Services Lateral Movement
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT1
APT3
APT39
APT41
APT5
Axiom
Blue Mockingbird
Chimera
Cobalt Group
Dragonfly
FIN10
FIN13
FIN6
FIN7
FIN8
Fox Kitten
HEXANE
Kimsuky
Lazarus Group
Leviathan
Magic Hound
OilRig
Patchwork
Silence
Wizard Spider
menuPass
Wizard Spider

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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 Registry node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.

Known False Positives

administrators may enable or disable this feature that may cause some false positive.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
the registry for rdp protocol was modified to enable in $dest$ 49 70 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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: 2