SV-29372r2: The system must limit how many times unacknowledged TCP data is retransmitted. | Windows Vista Security Technical Implementation Guide

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Assessment Title

Rule Text

The system must limit how many times unacknowledged TCP data is retransmitted.

Description

Discussion Text

In a SYN flood attack, the attacker sends a continuous stream of SYN packets to a server, and the server leaves the half-open connections open until it is overwhelmed and no longer is able to respond to legitimate requests.

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

IA Controls

NIST SP 800-53

Not mappedCCI-002385CCE-3460-3

Additional Details

Third-Party Tools

Responsibility

System Administrator

References

DPMS Target Windows Vista DISA DPMS Target Windows Vista 1029

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:485
# The system must limit how many times unacknowledged TCP data is retransmitted.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# registry_object (registry_test)
function test_1 {
  return ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters' -Name 'TcpMaxDataRetransmissions'))
}
# registry_object (registry_test)
function test_2 {
  return ((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters').GetValueKind('TcpMaxDataRetransmissions').ToString()]) -eq 'reg_dword')
}
# registry_object (registry_test)
function test_3 {
  return (-not ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters' -Name 'TcpMaxDataRetransmissions')))
}
# registry_object (registry_test)
function test_4 {
  return (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters' -Name 'TcpMaxDataRetransmissions' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'TcpMaxDataRetransmissions') -le 3)
}
# registry_object (registry_test)
function test_5 {
  return (-not ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters' -Name 'TcpMaxDataRetransmissions')))
}

if ((test_1 -and (test_2 -or test_3) -and (test_4 -or test_5))) {
  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_vista target this check assesses.

# oval:mil.disa.fso.windows:def:485
if ((Test-Path -Path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxDataRetransmissions") -or (Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxDataRetransmissions" -ErrorAction SilentlyContinue | Select-Object -ExpandProperty TcpMaxDataRetransmissions -ErrorAction SilentlyContinue) -le 3) {Write-Output "PASS"; Exit 0} else {Write-Output "FAIL"; Exit 1}

Remediation

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "MSS: (TcpMaxDataRetransmissions) How many times unacknowledged data is retransmitted (3 recommended, 5 is default)" to "3" or less.