TMA-IIS-2.3

Ensure 'forms authentication' require SSL

MediumLevel 1Automatediis

Description

Forms-based authentication can pass credentials across the network in clear text. It is therefore imperative that the traffic between client and server be encrypted using SSL, especially in cases where the site is publicly accessible. It is recommended that communications with any portion of a site using Forms Authentication be encrypted using SSL. Wherever forms authentication is the mode (root web.config and each site), forms requireSSL must be true. Compliant when forms authentication is not used. PowerShell 5.1 with the WebAdministration module; run elevated.

How it is checked

Audit method: Shell command

shell

Import-Module WebAdministration -ErrorAction Stop; $paths = @('MACHINE/WEBROOT') + @(Get-Website | ForEach-Object { "IIS:\Sites\$($_.Name)" }); $bad = @($paths | Where-Object { $a = Get-WebConfiguration -Filter 'system.web/authentication' -PSPath $_; $f = Get-WebConfiguration -Filter 'system.web/authentication/forms' -PSPath $_; [string]$a.mode -eq 'Forms' -and ($f.requireSSL -ne $true) }); if ($bad.Count -eq 0) { 'compliant' } else { 'noncompliant' }

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Set-WebConfigurationProperty -PSPath 'MACHINE/WEBROOT/APPHOST/<site>' -Filter system.web/authentication/forms -Name requireSSL -Value True

Properties

Operating systems: Any
Tags: iisauthentication
Reference: CIS Microsoft IIS 10 Benchmark v1.2.1 - 2.3 Ensure 'forms authentication' require SSL

Check this host

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

shell

tmaegis scan --target iis