MSS: (TcpMaxDataRetransmissions IPv6) How many times unacknowledged data is retransmitted (3 recommended, 5 is default)ID: oval:gov.nist.usgcb.windowsseven:def:20014 | Date: (C)2012-04-13 (M)2023-07-14 |
Class: COMPLIANCE | Family: windows |
The registry value entry TCPMaxDataRetransmissions was added to the template file in the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\ registry key. The entry appears as MSS: (TcpMaxDataRetransmissions) How many times unacknowledged data is retransmitted (3 recommended, 5 is default) in the SCE. This setting controls the number of times that TCP retransmits an individual data segment (non-connect segment) before the connection is aborted. The retransmission time-out is doubled with each successive retransmission on a connection. It is reset when responses resume. The base time-out value is dynamically determined by the measured round-trip time on the connection.
This entry sets the maximum number of retransmissions of a TCP segment containing data before the connection is abandoned. The retransmission timeout is doubled with each successive retransmission on a connection. It is reset when responses resume. The base timeout value is dynamically determined by the measured round-trip time on the connection.
Vulnerability:
A malicious user could exhaust a target computer's resources if it never sent any acknowledgment messages for data that was transmitted by the target computer.
Countermeasure:
Configure the TcpMaxDataRetransmissions entry to a value of 3.
Potential impact:
TCP starts a retransmission timer when each outbound segment is passed to the IP. If no acknowledgment is received for the data in a given segment before the timer expires, the segment is retransmitted up to three times.
Fix:
(1) GPO: 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)
(2) REG: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip6\Parameters!TcpMaxDataRetransmissions
Platform: |
Microsoft Windows 7 |