Details

Network devices must have TCP Keep-Alives enabled for TCP sessions.

Idle TCP sessions can be susceptible to unauthorized access and hijacking attacks. By default, routers do not continually test whether a previously connected TCP endpoint is still reachable. If one end of a TCP connection idles out or terminates abnormally, the opposite end of the connection may still believe the session is available. These ‘orphaned’ sessions use up valuable router resources and can also be hijacked by an attacker. To mitigate this risk, routers must be configured to send periodic keepalive messages to check that the remote end of a session is still connected. If the remote device fails to respond to the keepalive message, the sending router will clear the connection and free resources allocated to the session.

Solution

Configure the device to enable TCP Keep-Alives.

Supportive Information

The following resource is also helpful.

• https://iasecontent.disa.mil/stigs/zip/U_Network_L2_Switch_V8R27_STIG.zip

This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system Cisco.

References

• 800-53|SC-10.
• CAT|III
• Rule-ID|SV-5615r3_rule
• STIG-ID|NET0724
• Vuln-ID|V-5615

Source

• Tenable.com/audits