Detection: Windows RDP File Execution

Updated Date: 2024-11-21 ID: 0b6b12b9-8ba9-48fe-b3b8-b4e3e1cd22b4 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects when a Windows RDP client attempts to execute an RDP file from a temporary directory, downloads directory, or Outlook directories. This detection is significant as it can indicate an attempt for an adversary to deliver a .rdp file, which may be leveraged by attackers to control or exfiltrate data. If confirmed malicious, this activity could lead to unauthorized access, data theft, or further lateral movement within the network.

 1
 2| tstats count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process IN ("*\\AppData\\Local\\Temp\\*", "*\\Olk\\Attachments\\*", "*\\AppData\\Local\\Microsoft\\Outlook\\*", "*\\Content.Outlook\\*", "*\\Downloads\\*") AND Processes.process="*.rdp*" by Processes.process Processes.process_name Processes.user Processes.dest Processes.parent_process_name Processes.parent_process 
 3| `drop_dm_object_name(Processes)` 
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| eval execution_type=case( match(process, "\\\\Temp\\\\.*\\.(zip
 7|7z
 8|rar
 9|cab
10|tgz
11|gz
12|tar
13|iso
14|img
15|vhd
16|vhdx).*\\.*\\.rdp"), "temp_archive_execution", match(process, "\\\\Downloads\\\\"), "downloads_execution", match(process, "\\\\Temp\\\\"), "temp_execution", match(process, "\\\\Microsoft\\\\Outlook\\\\"), "outlook_execution", match(process, "\\\\Olk\\\\Attachments\\\\"), "outlook_execution", match(process, "\\\\Content.Outlook\\\\"), "outlook_execution", true(), "other" ), risk_score=case( execution_type="temp_archive_execution", "Critical", execution_type IN ("temp_execution", "outlook_execution"), "High", execution_type="downloads_execution", "Medium", true(), "Low" ), risk_reason=case( execution_type="temp_archive_execution", "RDP file executed directly from archive/disk image in Temp directory", execution_type="downloads_execution", "RDP file executed from Downloads directory (Could be legitimate admin activity)", execution_type="temp_execution", "RDP file executed from Temp directory", execution_type="outlook_execution", "RDP file executed from Outlook directories", true(), "Standard RDP file execution" ) 
17| sort - risk_score 
18| rename process_name as "RDP Process", parent_process_name as "Parent Process", process as "Command Line", user as "User", execution_type as "Execution Context", risk_score as "Risk Level", risk_reason as "Risk Details" 
19| fields - parent_process 
20| `windows_rdp_file_execution_filter`

Data Source

Name Platform Sourcetype Source
CrowdStrike ProcessRollup2 N/A 'crowdstrike:events:sensor' 'crowdstrike'
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_rdp_file_execution_filter search *
windows_rdp_file_execution_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
T1598.002 Spearphishing Attachment Reconnaissance
T1021.001 Remote Desktop Protocol Lateral Movement
KillChainPhase.EXPLOITAITON
KillChainPhase.RECONNAISSANCE
NistCategory.DE_CM
Cis18Value.CIS_10
Dragonfly
SideCopy
Sidewinder
Star Blizzard
APT1
APT3
APT39
APT41
APT5
Agrius
Aquatic Panda
Axiom
Blue Mockingbird
Chimera
Cobalt Group
Dragonfly
FIN10
FIN13
FIN6
FIN7
FIN8
Fox Kitten
HEXANE
INC Ransom
Indrik Spider
Kimsuky
Lazarus Group
Leviathan
Magic Hound
OilRig
Patchwork
Silence
Volt Typhoon
Wizard Spider
menuPass

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

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

False positives may be present based on administrators using RDP files for legitimate purposes. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A Windows RDP client attempted to execute an RDP file from a temporary directory, downloads directory, or Outlook directories on the endpoint $dest$. 42 60 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: 1