Windows PowerShell IIS Components WebGlobalModule Usage

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Description

The following analytic identifies the usage of PowerShell Cmdlets - New-WebGlobalModule, Enable-WebGlobalModule and Set-WebGlobalModule being utilized to create (new), enable (start) or modify a current IIS Module. These commands are equivalent to AppCmd.exe parameters. Adversaries may utilize these cmdlets as they are lesser known and perform the same activity as AppCmd.

• Type: Anomaly
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Web
• Last Updated: 2022-12-21
• Author: Michael Haag, Splunk
• ID: 33fc9f6f-0ce7-4696-924e-a69ec61a3d57

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1505	Server Software Component	Persistence

T1505.004

IIS Components

Persistence

Kill Chain Phase

• Installation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

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

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

windows_powershell_iis_components_webglobalmodule_usage_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

• _time
• ScriptBlockText
• Computer
• EventCode

How To Implement

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

• IIS Components

RBA

Risk Score	Impact	Confidence	Message
64.0	80	80	A PowerShell Cmdlet related to enabling, creating or modifying a IIS module has occurred on $Computer$.

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• https://learn.microsoft.com/en-us/powershell/module/webadministration/new-webglobalmodule?view=windowsserver2022-ps
• https://www.microsoft.com/en-us/security/blog/2022/12/12/iis-modules-the-evolution-of-web-shells-and-how-to-detect-them/
• https://www.crowdstrike.com/wp-content/uploads/2022/05/crowdstrike-iceapple-a-novel-internet-information-services-post-exploitation-framework-1.pdf
• https://unit42.paloaltonetworks.com/unit42-oilrig-uses-rgdoor-iis-backdoor-targets-middle-east/
• https://www.secureworks.com/research/bronze-union
• https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1505.004

Test Dataset

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

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