Ensure DES Cipher Suites is Disabled

HighLevel 1Automatediis

Description

The DES Cipher Suite is considered a weak symmetric-key cipher, therefore it is recommended that it be disabled. SCHANNEL\Ciphers\DES 56/56 must exist with Enabled=0 (read via the .NET registry API because the key names contain "/"). 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 }; $bad = @('DES 56/56' | Where-Object { $v = Get-Cipher $_; $null -eq $v -or [long]$v -ne 0 }); if ($bad.Count -eq 0) { '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\DES 56/56')).SetValue('Enabled', 0, 'DWord') for each listed cipher (PowerShell drive paths cannot contain '/'), then reboot.

Properties

Operating systems: Any
Tags: iistls
Reference: CIS Microsoft IIS 10 Benchmark v1.2.1 - 7.8 Ensure DES Cipher Suites is Disabled

Check this host

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

shell

tmaegis scan --target iis