Detection: Windows For Loop Usage Within Cmd.exe To Execute Commands

Description

The following analytic identifies the use of a for /f loop with the delims= option within cmd.exe, a technique commonly used to parse and extract data from the output of other commands. Adversaries and malicious scripts leverage this pattern to programmatically process command output for discovery, data extraction, or execution purposes while evading simpler detection logic.

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
 8Processes.parent_process="*for /f*"
 9Processes.parent_process="*delims=*"
10NOT Processes.user="SYSTEM"
11NOT Processes.user="*$"
12NOT Processes.parent_process IN (
13    "*__VIARelease*",
14    "*:\\Program Files\\Microsoft SQL Server\\*",
15    "*^
16| findstr *"
17)
18
19by Processes.action Processes.dest Processes.original_file_name
20   Processes.parent_process Processes.parent_process_exec
21   Processes.parent_process_guid Processes.parent_process_id
22   Processes.parent_process_name Processes.parent_process_path
23   Processes.process Processes.process_exec Processes.process_guid
24   Processes.process_hash Processes.process_id
25   Processes.process_integrity_level Processes.process_name
26   Processes.process_path Processes.user Processes.user_id
27   Processes.vendor_product
28
29
30| `drop_dm_object_name(Processes)`
31
32| `security_content_ctime(firstTime)`
33
34| `security_content_ctime(lastTime)`
35
36| `windows_for_loop_usage_within_cmd_exe_to_execute_commands_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'

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

Administrators or power users may use for /f loops with delims= in legitimate scripts for automation or troubleshooting purposes.

Associated Analytic Story

• Living Off The Land

• Windows Post-Exploitation

• Suspicious Command-Line Executions

• Compromised Windows Host

• Fake CAPTCHA Campaigns

Intermediate Findings

Threat Objects

References

• https://packetwatch.com/resources/threat-profile/clickfix-abuses-finger-to-deliver-castleloader

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