Detection: Windows OneDrive Share Mounted via Net

Description

The following analytic detects the use of net.exe or net1.exe to mount a OneDrive share as a network drive. This behavior may indicate an attempt to stage, access, or exfiltrate data through a cloud-hosted WebDAV path rather than a traditional file share. If confirmed malicious, an attacker could use the mounted share to move data outside the environment over trusted cloud infrastructure.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8`process_net`
 9Processes.process="*use*"
10Processes.process="*https://d.docs.live.net*"
11
12by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
13   Processes.parent_process_name Processes.parent_process_exec Processes.action
14   Processes.dest Processes.process_current_directory Processes.process_path
15   Processes.process_integrity_level Processes.original_file_name Processes.parent_process
16   Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
17   Processes.process_guid Processes.process_id Processes.user Processes.process_name
18
19
20| `drop_dm_object_name(Processes)`
21
22| `security_content_ctime(firstTime)`
23
24| `security_content_ctime(lastTime)`
25
26| `windows_onedrive_share_mounted_via_net_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

Legitimate users may mount OneDrive shares for synchronized access or backup purposes. Monitor for unauthorized or unusual mounting activity to reduce false alerts.

Associated Analytic Story

• Data Exfiltration

Risk Based Analytics (RBA)

Risk Message:

Potential OneDrive share mounted on $dest$ via $process$.

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