Detection: Windows WinRAR Launched Outside Default Installation Directory

Description

This Analytics detects the execution of WinRAR or RAR outside the default installation directory. This behavior can be significant as it could indicate attempts to archive collected sensitive data from the endpoint for exfiltration. We recommend reviewing the process path and the parent process path to determine if the execution is legitimate and if possible validate the data being archived.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
 3  from datamodel=Endpoint.Processes where
 4  Processes.process_name IN ("Winrar.exe", "rar.exe")
 5  NOT Processes.process_path IN (
 6    "*:\\Program Files (x86)\\WinRAR\\*",
 7    "*:\\Program Files\\WinRAR\\*"
 8  )
 9  by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
10  Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
11  Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
12  Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
13  Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
14
15| `drop_dm_object_name(Processes)`
16
17| `security_content_ctime(firstTime)`
18
19| `security_content_ctime(lastTime)`
20
21| `windows_winrar_launched_outside_default_installation_directory_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'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 are expected from machines where the default installation path was changed. Apply additional filters accordingly.

Associated Analytic Story

• BlankGrabber Stealer

Risk Based Analytics (RBA)

Risk Message:

A [$process_name$] execution in [$process_path$] was identified on endpoint [$dest$] by user [$user$].

References

• https://malpedia.caad.fkie.fraunhofer.de/details/py.blankgrabber

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: 1