TMA-IIS-4.9

Ensure 'notListedIsapisAllowed' is set to false

HighLevel 1Automatediis

Description

The notListedIsapisAllowed attribute is a server-level setting that is located in the ApplicationHost.config file in the <isapiCgiRestriction> element of the <system.webServer> section under <security>. This element ensures that malicious users cannot copy unauthorized ISAPI binaries to the Web server and then run them. It is recommended that notListedIsapisAllowed be set to false. isapiCgiRestriction notListedIsapisAllowed must be false. PowerShell 5.1 with the WebAdministration module; run elevated.

How it is checked

Audit method: Shell command

shell

Import-Module WebAdministration -ErrorAction Stop; $c = Get-WebConfiguration -Filter 'system.webServer/security/isapiCgiRestriction' -PSPath 'MACHINE/WEBROOT/APPHOST'; if ($c.notListedIsapisAllowed -eq $false) { 'compliant' } else { 'noncompliant' }

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Set-WebConfigurationProperty -PSPath 'MACHINE/WEBROOT/APPHOST' -Filter system.webServer/security/isapiCgiRestriction -Name notListedIsapisAllowed -Value False

Properties

Operating systems: Any
Tags: iisrequest-filtering
Reference: CIS Microsoft IIS 10 Benchmark v1.2.1 - 4.9 Ensure 'notListedIsapisAllowed' is set to false

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target iis