Title

The Juniper EX switch must be configured to prune the default VLAN from all trunked interfaces that do not require it. (Cat II impact)

Discussion

All unassigned interfaces are placed into the default VLAN and devices connected to enabled, but unassigned interfaces can communicate within that VLAN. Although the default VLAN is not automatically assigned to any trunked interface, if the default VLAN must be trunked or a misconfigured trunk unintentionally includes the default VLAN, unauthorized devices connected to enabled but unassigned access interfaces could gain network connectivity beyond the local switch.

Check Content

Review the switch configuration and verify that the default VLAN is pruned from trunk links that do not require it. [edit interfaces] <interface name> { unit 0 { family ethernet-switching { interface-mode trunk; vlan { members [ vlan_name ... vlan_name ]; } } } } If the default VLAN is not pruned from trunk links that should not be transporting frames for that VLAN, this is a finding.

Fix Text

Remove unnecessary VLANs from trunked interfaces. delete interfaces <trunked interface name> unit 0 family ethernet-switching vlan members <default | other unnecessary VLAN name>

Additional Identifiers

Rule ID: SV-253968r843937_rule

Vulnerability ID: V-253968

Group Title: SRG-NET-000512-L2S-000009

Expert Comments

CCIs tied to check.

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