Detection: Windows PowerShell IIS Components WebGlobalModule Usage

Description

The following analytic detects the usage of PowerShell Cmdlets - New-WebGlobalModule, Enable-WebGlobalModule, and Set-WebGlobalModule, which are used to create, enable, or modify IIS Modules. This detection leverages PowerShell Script Block Logging, specifically monitoring EventCode 4104 for these cmdlets. This activity is significant as adversaries may use these lesser-known cmdlets to manipulate IIS configurations, similar to AppCmd.exe, potentially bypassing traditional defenses. If confirmed malicious, this could allow attackers to persist in the environment, manipulate web server behavior, or escalate privileges.

1`powershell` EventCode=4104 ScriptBlockText IN("*New-WebGlobalModule*","*Enable-WebGlobalModule*","*Set-WebGlobalModule*") 
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)`  
5| `windows_powershell_iis_components_webglobalmodule_usage_filter`

Data Source

Name Platform Sourcetype Source
Powershell Script Block Logging 4104 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'

Macros Used

Name Value
powershell (source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational")
windows_powershell_iis_components_webglobalmodule_usage_filter search *
windows_powershell_iis_components_webglobalmodule_usage_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
T1505 Server Software Component Persistence
T1505.004 IIS Components Persistence
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10

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

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

It is possible administrators or scripts may run these commands, filtering may be required.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A PowerShell Cmdlet related to enabling, creating or modifying a IIS module has occurred on $Computer$. 64 80 80
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Passing N/A N/A N/A
Unit Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/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: 3