The use of DES encryption suites must not be allowed for Kerberos encryption.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-21954	WN12-SO-000064	SV-53179r2_rule		Medium

Description
Certain encryption types are no longer considered secure. By default, Windows 2012/R2 does not use the DES encryption suites. If the configuration of allowed Kerberos encryption suites is needed, the DES encryption suites must not be included.

STIG	Date
Windows Server 2012 / 2012 R2 Domain Controller Security Technical Implementation Guide	2016-12-19

Details

Check Text ( C-61749r2_chk )
Verify whether the registry key below exists. If it does not exist or the value is "0", this is not a finding. If the registry key exists and contains a value other than "0", continue below. The values are determined by the selection of encryption suites in the policy Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network Security: Configure encryption types allowed for Kerberos". Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters\ Value Name: SupportedEncryptionTypes Type: REG_DWORD Due to the number of possible combinations that may include the DES encryption types, it is not possible to include all acceptable values as viewed directly in the registry. If the registry key does exist, the value must be converted to binary to determine configuration of specific bits. This will determine whether this is a finding. Note the value for the registry key. For example, when all suites, including the DES suites are selected, the value will be "0x7fffffff (2147483647)". Open the Windows calculator (Run/Search for "calc"). Select "View", then "Programmer". Select "Dword" and either "Hex" or "Dec". Enter the appropriate form of the value found for the registry key (e.g., Hex - enter 0x7fffffff, Dec - enter 2147483647) Select "Bin". The returned value may vary in length, up to 32 characters. If the either of 2 right most characters are "1", this is a finding. If the both of 2 right most characters are "0", this is not a finding.

Check Text ( C-61749r2_chk )

Verify whether the registry key below exists. If it does not exist or the value is "0", this is not a finding.
If the registry key exists and contains a value other than "0", continue below.

The values are determined by the selection of encryption suites in the policy Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network Security: Configure encryption types allowed for Kerberos".

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters\
Value Name: SupportedEncryptionTypes
Type: REG_DWORD

Due to the number of possible combinations that may include the DES encryption types, it is not possible to include all acceptable values as viewed directly in the registry.

If the registry key does exist, the value must be converted to binary to determine configuration of specific bits. This will determine whether this is a finding.

Note the value for the registry key.
For example, when all suites, including the DES suites are selected, the value will be "0x7fffffff (2147483647)".

Open the Windows calculator (Run/Search for "calc").
Select "View", then "Programmer".
Select "Dword" and either "Hex" or "Dec".
Enter the appropriate form of the value found for the registry key (e.g., Hex - enter 0x7fffffff, Dec - enter 2147483647)
Select "Bin".
The returned value may vary in length, up to 32 characters.
If the either of 2 right most characters are "1", this is a finding.
If the both of 2 right most characters are "0", this is not a finding.

Fix Text (F-66513r3_fix)
The default system configuration does not use DES encryption for Kerberos and supports this requirement. If Kerberos encryption types must be configured, ensure the following are not selected: DES_CBC_CRC DES_CBC_MD5 If the policy for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: Configure encryption types allowed for Kerberos" is configured, only the following selections are allowed: RC4_HMAC_MD5 AES128_HMAC_SHA1 AES256_HMAC_SHA1 Future encryption types

Fix Text (F-66513r3_fix)

The default system configuration does not use DES encryption for Kerberos and supports this requirement. If Kerberos encryption types must be configured, ensure the following are not selected:

DES_CBC_CRC
DES_CBC_MD5

If the policy for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: Configure encryption types allowed for Kerberos" is configured, only the following selections are allowed:

RC4_HMAC_MD5
AES128_HMAC_SHA1
AES256_HMAC_SHA1
Future encryption types