Detection: GPUpdate with no Command Line Arguments with Network

Updated Date: 2024-09-30 ID: 2c853856-a140-11eb-a5b5-acde48001122 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the execution of gpupdate.exe without command line arguments and with an active network connection. This behavior is identified using Endpoint Detection and Response (EDR) telemetry, focusing on process execution and network traffic data. It is significant because gpupdate.exe typically runs with specific arguments, and its execution without them, especially with network activity, is often associated with malicious software like Cobalt Strike. If confirmed malicious, this activity could indicate an attacker leveraging gpupdate.exe for lateral movement, command and control, or other nefarious purposes, potentially leading to system compromise.

Search

 1
 2| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where Processes.process_name=gpupdate.exe by _time span=1h  Processes.process_id Processes.process_name Processes.dest Processes.user Processes.process_path Processes.process Processes.parent_process_name 
 3| `drop_dm_object_name(Processes)` 
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| regex process="(?i)(gpupdate\.exe.{0,4}$)"
 7| join  process_id [
 8| tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port != 0 by All_Traffic.process_id All_Traffic.dest All_Traffic.dest_port 
 9| `drop_dm_object_name(All_Traffic)` 
10| rename dest as C2 ] 
11| table _time user dest parent_process_name process_name process_path process process_id dest_port C2 
12| `gpupdate_with_no_command_line_arguments_with_network_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 1	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Sysmon EventID 3	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
gpupdate_with_no_command_line_arguments_with_network_filter	`search *`

gpupdate_with_no_command_line_arguments_with_network_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
T1055	Process Injection	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_CM

Cis18Value.CIS_10

APT32

APT37

APT41

APT5

Cobalt Group

Kimsuky

PLATINUM

Silence

TA2541

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

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

Limited false positives may be present in small environments. Tuning may be required based on parent process.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Process gpupdate.exe with parent_process $parent_process_name$ is executed on $dest$ by user $user$, followed by an outbound network connection to $C2$ on port $dest_port$. This behaviour is seen with cobaltstrike.	81	90	90

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: 5