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


Overview

Finding ID Version Rule ID IA Controls Severity
V-4438 5.098 SV-25077r2_rule Low
Description
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.
STIG Date
Windows 7 Security Technical Implementation Guide 2016-12-19

Details

Check Text ( C-62013r1_chk )
Analyze the system using the Security Configuration and Analysis snap-in.
Expand the Security Configuration and Analysis tree view.
Navigate to Local Policies >> Security Options.

If the value for "MSS: (TcpMaxDataRetransmissions) 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\Tcpip\Parameters\

Value Name: TcpMaxDataRetransmissions

Value Type: REG_DWORD
Value: 3 (or less)
Fix Text (F-66909r1_fix)
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.