Detection: Windows Modify Registry DisableRemoteDesktopAntiAlias

Updated Date: 2024-05-16 ID: 4927c6f1-4667-42e6-bd7a-f5222116386b Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects modifications to the Windows registry key "DisableRemoteDesktopAntiAlias" with a value set to 0x00000001. This detection leverages data from the Endpoint datamodel, specifically monitoring changes in the Registry node. This activity is significant as it may indicate the presence of DarkGate malware, which alters this registry setting to enhance its remote desktop capabilities. If confirmed malicious, this modification could allow an attacker to maintain persistence and control over the compromised host, potentially leading to further exploitation and data exfiltration.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path = "*\\Terminal Services\\DisableRemoteDesktopAntiAlias"  Registry.registry_value_data = 0x00000001 by  Registry.registry_path Registry.registry_value_name Registry.registry_value_data Registry.process_guid Registry.action Registry.user Registry.dest 
3| `drop_dm_object_name(Registry)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_modify_registry_disableremotedesktopantialias_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_modify_registry_disableremotedesktopantialias_filter search *
windows_modify_registry_disableremotedesktopantialias_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 Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT19
APT32
APT38
APT41
Blue Mockingbird
Dragonfly
Earth Lusca
Ember Bear
FIN8
Gamaredon Group
Gorgon Group
Kimsuky
LuminousMoth
Magic Hound
Patchwork
Silence
TA505
Threat Group-3390
Turla
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, however is not common. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
the registry for remote desktop settings was modified to be DisableRemoteDesktopAntiAlias on $dest$. 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