TMA-IIS-4.5

Ensure Double-Encoded requests will be rejected

MoyenneNiveau 1Automatiséeiis

Description

This Request Filter feature prevents attacks that rely on double-encoded requests and applies if an attacker submits a double-encoded request to IIS. When the double- encoded requests filter is enabled, IIS will go through a two iteration process of normalizing the request. If the first normalization differs from the second, the request is rejected and the error code is logged as a 404.11. requestFiltering allowDoubleEscaping must be false at server level and for every site. PowerShell 5.1 with the WebAdministration module; run elevated.

Méthode de vérification

Méthode d'audit: Commande shell

shell

Import-Module WebAdministration -ErrorAction Stop; $paths = @('MACHINE/WEBROOT/APPHOST') + @(Get-Website | ForEach-Object { "IIS:\Sites\$($_.Name)" }); $bad = @($paths | Where-Object { $c = Get-WebConfiguration -Filter 'system.webServer/security/requestFiltering' -PSPath $_; $c.allowDoubleEscaping -ne $false }); if ($bad.Count -eq 0) { 'compliant' } else { 'noncompliant' }

Sortie attendue: compliant

Méthode de correction

Méthode de correction: Recommandation ou correctif d'infrastructure

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

Propriétés

Systèmes d'exploitation: Tous
Étiquettes: iisrequest-filtering
Référence: CIS Microsoft IIS 10 Benchmark v1.2.1 - 4.5 Ensure Double-Encoded requests will be rejected

Vérifier cet hôte

Exécutez cette commande sur une machine que vous êtes autorisé à auditer. L'analyse est en lecture seule.

shell

tmaegis scan --target iis