Detection: WMIC XSL Execution via URL

Description

The following analytic detects wmic.exe loading a remote XSL script via a URL. This detection leverages Endpoint Detection and Response (EDR) data, focusing on command-line executions that include HTTP/HTTPS URLs and the /FORMAT switch. This activity is significant as it indicates a potential application control bypass, allowing adversaries to execute JScript or VBScript within an XSL file. If confirmed malicious, this technique can enable attackers to execute arbitrary code, escalate privileges, or maintain persistence using a trusted Windows tool, posing a severe threat to the environment.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
 3as lastTime from datamodel=Endpoint.Processes where 
 4`process_wmic` 
 5Processes.process IN ("*http://*", "*https://*") 
 6Processes.process="*/format:*" 
 7by Processes.action Processes.dest Processes.original_file_name Processes.parent_process 
 8   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id 
 9   Processes.parent_process_name Processes.parent_process_path Processes.process 
10   Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id 
11   Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user 
12   Processes.user_id Processes.vendor_product
13
14| `drop_dm_object_name(Processes)` 
15
16| `security_content_ctime(firstTime)` 
17
18| `security_content_ctime(lastTime)`
19
20| `wmic_xsl_execution_via_url_filter`

Data Source

Name	Platform	Sourcetype	Source
Cisco Network Visibility Module Flow Data	Network	'cisco:nvm:flowdata'	'not_applicable'
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 are limited as legitimate applications typically do not download files or xsl using WMIC. Filter as needed.

Associated Analytic Story

• Cisco Network Visibility Module Analytics

• Compromised Windows Host

• Suspicious WMI Use

Risk Based Analytics (RBA)

Risk Message:

An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ utilizing wmic to download a remote XSL script.

References

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1220/T1220.md

• https://web.archive.org/web/20190814201250/https://subt0x11.blogspot.com/2018/04/wmicexe-whitelisting-bypass-hacking.html

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1220/T1220.md#atomic-test-4---wmic-bypass-using-remote-xsl-file

• https://securitydatasets.com/notebooks/atomic/windows/defense_evasion/SDWIN-201017061100.html

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: 10