Detection: Notepad with no Command Line Arguments

Description

The following analytic identifies instances where Notepad.exe is launched without any command line arguments, a behavior commonly associated with the SliverC2 framework. This detection leverages process creation events from Endpoint Detection and Response (EDR) agents, focusing on processes initiated by Notepad.exe within a short time frame. This activity is significant as it may indicate an attempt to inject malicious code into Notepad.exe, a known tactic for evading detection. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to system compromise and unauthorized access.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes where Processes.process_name=notepad.exe AND Processes.action!="blocked" by host _time span=1h Processes.process_id Processes.process_name Processes.dest Processes.process_path Processes.process Processes.parent_process_name Processes.parent_process 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| regex process="(?i)(notepad\.exe.{0,4}$)" 
7| `notepad_with_no_command_line_arguments_filter`

Data Source

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

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

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 and filtering may need to occur based on organization endpoint behavior.

Associated Analytic Story

• BishopFox Sliver Adversary Emulation Framework

Risk Based Analytics (RBA)

References

• https://www.microsoft.com/en-us/security/blog/2022/08/24/looking-for-the-sliver-lining-hunting-for-emerging-command-and-control-frameworks/

• https://www.cybereason.com/blog/sliver-c2-leveraged-by-many-threat-actors#Purple-Team-Section

Detection Testing

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: 4