SV-250541r1117186: Allow Fallback to SSL 3.0 (Internet Explorer) must be disabled. | Microsoft Internet Explorer 11 STIG SCAP Benchmark

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Assessment Title

Rule Text

Allow Fallback to SSL 3.0 (Internet Explorer) must be disabled.

Description

Discussion Text

This parameter ensures only DoD-approved ciphers and algorithms are enabled for use by the web browser by blocking an insecure fallback to SSL when TLS 1.0 or greater fails. Satisfies: SRG-APP-000514, SRG-APP-000555, SRG-APP-000625, SRG-APP-000630, SRG-APP-000635

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

IA Controls

NIST SP 800-53

Not mappedCCI-002450SV-79219V-64729

References

DPMS Target Microsoft Internet Explorer 11 DISA DPMS Target Microsoft Internet Explorer 11 4095

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.ie:def:581
# Allow Fallback to SSL 3.0 (Internet Explorer) 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.

# Verifies 'Allow Fallback to SSL 3.0 (Internet Explorer)' is set to 'Enabled' with 'Allow insecure fallback for:' set to 'No Sites'
# 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\Microsoft\Windows\CurrentVersion\Internet Settings').GetValueKind('EnableSSL3Fallback').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings' -Name 'EnableSSL3Fallback' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'EnableSSL3Fallback') -eq 0))
}

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

SCC Assessment

The automated check DISA's SCAP Compliance Checker runs to assess this control. Pick a release below to see exactly what it evaluates on the target system.

SCC version

Not available for this version yet.

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 ms_ie11 target this check assesses.

# oval:mil.disa.fso.ie:def:581
$registryPath = "HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings"
$registryKey = "EnableSSL3Fallback"
if (-Not (Test-Path $registryPath)) { $exists = $false } else { $exists = $true }
if ($exists -eq $true) { $value = (Get-ItemProperty -Path $registryPath -Name $registryKey -ErrorAction SilentlyContinue).$registryKey } else { $value = 1 }
if (($value -eq 0) -or (-Not $exists)) { Write-Output "PASS"; Exit 0 } else { Write-Output "FAIL"; Exit 1 }

Remediation

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Internet Explorer >> Security Features >> "Allow fallback to SSL 3.0 (Internet Explorer)" to "Enabled", and select "No Sites" from the drop-down box.