SV-25277r3: The use of DES encryption suites must not be allowed for Kerberos encryption. | Windows 7 Security Technical Implementation Guide

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Assessment Title

Rule Text

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

Description

Discussion Text

Certain encryption types are no longer considered secure. This setting configures a minimum encryption type for Kerberos, preventing the use of the DES encryption suites.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000803CCE-9532-3

Additional Details

Responsibility

System Administrator

References

DPMS Target Windows 7 DISA DPMS Target Windows 7 1712

Checks

OVAL

oval:mil.disa.fso.windows:var:375300 ← xccdf_mil.disa.stig_value_Network_Security_Configure_encryption_types_allowed_for_Kerberos_var

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

# Windows PowerShell
# Reconstructed from oval:mil.disa.fso.windows:def:3753
# The use of DES encryption suites must not be allowed for Kerberos encryption.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Verifies 'Network Security: Configure encryption types allowed for Kerberos' is configured with at least one encryption type selected
# registry_object (registry_test)
function test_1 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters').GetValueKind('SupportedEncryptionTypes').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Name 'SupportedEncryptionTypes' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'SupportedEncryptionTypes') -gt 0))
}
# Verifies 'Network Security: Configure encryption types allowed for Kerberos' is configured with 'DES_CBC_CRC' deselected
# registry_object (registry_test)
function test_2 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters').GetValueKind('SupportedEncryptionTypes').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Name 'SupportedEncryptionTypes' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'SupportedEncryptionTypes') -eq 1))
}
# Verifies 'Network Security: Configure encryption types allowed for Kerberos' is configured with 'DES_CBC_MD5' deselected
# registry_object (registry_test)
function test_3 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters').GetValueKind('SupportedEncryptionTypes').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Name 'SupportedEncryptionTypes' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'SupportedEncryptionTypes') -eq 2))
}

if ((test_1 -and test_2 -and test_3)) {
  Write-Output "PASS"
} else {
  Write-Output "FAIL"
}

Assessment Script Powered by AISyntax-verified

A standalone PowerShell script to assess this control automatically. Review before running it in your environment.

Syntax-checked as valid PowerShell. Not executed here — running it for real needs the actual windows_7 target this check assesses.

# oval:mil.disa.fso.windows:def:3753
if (!(Get-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters" -Name SupportedEncryptionTypes -ErrorAction SilentlyContinue)) {exit 1} else {if ((Get-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters" -Name SupportedEncryptionTypes).SupportedEncryptionTypes -band 1 -eq 0 -and (Get-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters" -Name SupportedEncryptionTypes -ErrorAction SilentlyContinue).SupportedEncryptionTypes -band 2 -eq 0) {exit 0} else {exit 1}}

Remediation

Configure the policy 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:

				RC4_HMAC_MD5
				AES128_HMAC_SHA1
				AES256_HMAC_SHA1
				Future encryption types

				Options such as RC4_HMAC_MD5 may also be excluded to align with STIGs for later Windows versions.