Kerberos encryption types must be configured to prevent the use of DES and RC4 encryption suites.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-21954	WN12-SO-000064	SV-53179r3_rule		Medium

Description
Certain encryption types are no longer considered secure. The DES and RC4 encryption suites must not be used for Kerberos encryption.

STIG	Date
Windows Server 2012/2012 R2 Domain Controller Security Technical Implementation Guide	2018-09-05

Details

Check Text ( C-80885r1_chk )
If the following registry value does not exist or is not configured as specified, this is a finding. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters\ Value Name: SupportedEncryptionTypes Value Type: REG_DWORD Value: 0x7ffffff8 (2147483640)

Fix Text (F-87993r1_fix)
Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: Configure encryption types allowed for Kerberos" to "Enabled" with only the following selected: AES128_HMAC_SHA1 AES256_HMAC_SHA1 Future encryption types Removing the previously allowed RC4_HMAC_MD5 encryption suite should be thoroughly tested before changing.

Fix Text (F-87993r1_fix)

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: Configure encryption types allowed for Kerberos" to "Enabled" with only the following selected:

AES128_HMAC_SHA1
AES256_HMAC_SHA1
Future encryption types

Removing the previously allowed RC4_HMAC_MD5 encryption suite should be thoroughly tested before changing.