Detection: Windows List ENV Variables Via SET Command From Uncommon Parent

Updated Date: 2025-01-17 ID: aec157f4-8783-4584-aca6-754c4dc7fba9 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic identifies a suspicious process command line fetching environment variables using the cmd.exe "set" command, with a non-shell parent process. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions and parent process names. This activity could be significant as it is commonly associated with malware like Qakbot, which uses this technique to gather system information. If confirmed malicious, this behavior could indicate that the parent process has been compromised, potentially allowing attackers to execute arbitrary commands, escalate privileges, or persist within the environment.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name="cmd.exe" Processes.process IN ("*/c set", "*/c \"set") AND NOT Processes.parent_process_name IN ("cmd.exe", "explorer.exe", "powershell*" "pwsh.exe") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_list_env_variables_via_set_command_from_uncommon_parent_filter`

Data Source

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

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_list_env_variables_via_set_command_from_uncommon_parent_filter search *
windows_list_env_variables_via_set_command_from_uncommon_parent_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1055 Process Injection Defense Evasion
Exploitation
DE.AE
CIS 10
APT32
APT37
APT41
APT5
Cobalt Group
Kimsuky
PLATINUM
Silence
TA2541
Turla
Wizard Spider

Default Configuration

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

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

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

shell process that are not included in this search may cause False positive. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

non-shell parent process has a child process $process_name$ with a commandline $process$ to fetch env variables on $dest$

Risk Object Risk Object Type Risk Score Threat Objects
dest system 56 No Threat Objects

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

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