Title

TCP connection response retransmissions are not controlled. (Cat III impact)

Discussion

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.

Check Content

Fix Text

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “MSS: (TcpMaxConnectResponseRetransmissions) SYN-ACK retransmissions when a connection is not acknowledged” to “3 & 6 seconds, half-open connections dropped after 21 seconds”, “3 seconds, half-open connections dropped after 9 seconds” or “No retransmission, half-open connections dropped after 3 seconds”.

Additional Identifiers

Rule ID: SV-29612r1_rule

Vulnerability ID: V-4437

Group Title:

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.