SV-251571r960963: Firefox deprecated ciphers must be disabled. | Mozilla Firefox for Windows STIG SCAP Benchmark

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Assessment Title

Rule Text

Firefox deprecated ciphers must be disabled.

Description

Discussion Text

A weak cipher is defined as an encryption/decryption algorithm that uses a key of insufficient length. Using an insufficient length for a key in an encryption/decryption algorithm opens up the possibility (or probability) that the encryption scheme could be broken.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000381

References

DPMS Target Mozilla Firefox 2021 VERSION DISA DPMS Target Mozilla Firefox 2021 VERSION 5446

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.stig.firefox.windows:def:126
# Firefox deprecated ciphers must be disabled.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Software\Policies\Mozilla\Firefox\DisabledCiphers\TLS_RSA_WITH_3DES_EDE_CBC_SHA is set to 1 reg_dword
# 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\Policies\Mozilla\Firefox\DisabledCiphers').GetValueKind('TLS_RSA_WITH_3DES_EDE_CBC_SHA').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\DisabledCiphers' -Name 'TLS_RSA_WITH_3DES_EDE_CBC_SHA' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'TLS_RSA_WITH_3DES_EDE_CBC_SHA') -eq 1))
}

if (test_1) {
  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 moz_firefox_windows target this check assesses.

# OVAL Definition: oval:mil.disa.stig.firefox.windows:def:126
$compliant = Test-Path "HKLM:\SOFTWARE\Policies\Mozilla\Firefox\DisabledCiphers\TLS_RSA_WITH_3DES_EDE_CBC_SHA" -and ((Get-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Mozilla\Firefox\DisabledCiphers\TLS_RSA_WITH_3DES_EDE_CBC_SHA").psobject.properties.value -eq 1)
if ($compliant) { Write-Output "PASS"; Exit 0 } else { Write-Output "FAIL"; Exit 1 }

Remediation

Windows group policy:
1. Open the group policy editor tool with "gpedit.msc".
2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\Disabled Ciphers
Policy Name: TLS_RSA_WITH_3DES_EDE_CBC_SHA
Policy State: Enabled

macOS "plist" file:
Add the following:
<key>DisabledCiphers</key>
  <dict>
    <key>TLS_RSA_WITH_3DES_EDE_CBC_SHA</key>
    <true/>
  </dict>

Linux "policies.json" file:
Add the following in the policies section:
"DisabledCiphers": {
  "TLS_RSA_WITH_3DES_EDE_CBC_SHA": true
}