Title

The system must be configured to limit how often keep-alive packets are sent. (Cat III impact)

Discussion

This setting controls how often TCP sends a keep-alive packet in attempting to verify that an idle connection is still intact. A higher value could allow an attacker to cause a denial of service with numerous connections.

Check Content

If the following registry value does not exist or is not configured as specified, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \System\CurrentControlSet\Services\Tcpip\Parameters\ Value Name: KeepAliveTime Value Type: REG_DWORD Value: 300000 (or less)

Fix Text

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> "MSS: (KeepAliveTime) How often keep-alive packets are sent in milliseconds" to "300000 or 5 minutes (recommended)" or less. (See "Updating the Windows Security Options File" in the STIG Overview document if MSS settings are not visible in the system's policy tools.)

Additional Identifiers

Rule ID: SV-226305r852143_rule

Vulnerability ID: V-226305

Group Title: SRG-OS-000420-GPOS-00186

Expert Comments

CCIs tied to check.

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