Ensure AES 256/256 Cipher Suite is Enabled

MediumLevel 1Automatediis

Description

AES 256/256 is the most recent and mature cipher suite for protecting the confidentiality and integrity of HTTP traffic. Enabling AES 256/256 is recommended. Note: AES 256/256 is enabled by default starting with Server 2012 and 2012 R2. SCHANNEL\Ciphers\AES 256/256 must exist with Enabled=1 (read via the .NET registry API). PowerShell 5.1; reads the registry (run elevated).

How it is checked

Audit method: Windows registry

registry

$c = 'SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers'; function Get-Cipher($n) { $k = [Microsoft.Win32.Registry]::LocalMachine.OpenSubKey("$c\$n"); $v = $null; if ($k) { $v = $k.GetValue('Enabled'); $k.Close() }; $v }; $v = Get-Cipher 'AES 256/256'; if ($null -ne $v -and [long]$v -eq 1) { 'compliant' } else { 'noncompliant' }

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

([Microsoft.Win32.Registry]::LocalMachine.CreateSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\AES 256/256')).SetValue('Enabled', 1, 'DWord'), then reboot.

Properties

Operating systems: Any
Tags: iistls
Reference: CIS Microsoft IIS 10 Benchmark v1.2.1 - 7.11 Ensure AES 256/256 Cipher Suite is Enabled

Check this host

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

shell

tmaegis scan --target iis