Title

IPv6 TCP data retransmissions must be configured to prevent resources from becoming exhausted. (Cat III impact)

Discussion

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.

Check Content

Analyze the system using the Security Configuration and Analysis snap-in. (See "Performing Analysis with the Security Configuration and Analysis Snap-in" in the STIG Overview document.) Expand the Security Configuration and Analysis tree view. Navigate to Local Policies >> Security Options. (See "Updating the Windows Security Options File" in the STIG Overview document if MSS settings are not visible in the system's policy tools.) If the value for "MSS: (TcpMaxDataRetransmissions IPv6) How many times unacknowledged data is retransmitted (3 recommended, 5 is default)" is not set to "3" or less, this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\ Value Name: TcpMaxDataRetransmissions Type: REG_DWORD Value: 3 (or less)

Fix Text

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.

Additional Identifiers

Rule ID: SV-48433r3_rule

Vulnerability ID: V-21956

Group Title: IPv6 TCP Data Retransmissions

Expert Comments

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