IPv6 TCP data retransmissions must be configured to prevent resources from becoming exhausted.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-21956	WN12-SO-000047	SV-53181r2_rule		Low

Description
Configuring Windows to limit the number of times that IPv6 TCP retransmits unacknowledged data segments before aborting the attempt helps prevent resources from becoming exhausted.

STIG	Date
Windows Server 2012/2012 R2 Member Server Security Technical Implementation Guide	2020-06-16

Details

Check Text ( C-47487r3_chk )
If the following registry value does not exist or is not configured as specified, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\ Value Name: TcpMaxDataRetransmissions Value Type: REG_DWORD Value: 3 (or less)

Fix Text (F-46107r2_fix)
Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "MSS: (TcpMaxDataRetransmissions IPv6) How many times unacknowledged data is retransmitted (3 recommended, 5 is default)" to "3" or less. (See "Updating the Windows Security Options File" in the STIG Overview document if MSS settings are not visible in the system's policy tools.)

Fix Text (F-46107r2_fix)

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "MSS: (TcpMaxDataRetransmissions IPv6) How many times unacknowledged data is retransmitted (3 recommended, 5 is default)" to "3" or less.

(See "Updating the Windows Security Options File" in the STIG Overview document if MSS settings are not visible in the system's policy tools.)