The management VLAN is not pruned from any VLAN trunk links belonging to the managed network’s infrastructure.

From Layer 2 Switch Security Technical Implementation Guide

Part of The management VLAN is not pruned from trunk links

Associated with IA controls: ECSC-1

SV-19081r1_rule The management VLAN is not pruned from any VLAN trunk links belonging to the managed network’s infrastructure.

Vulnerability discussion

The OOBM access switch will connect to the management interface of the managed network elements. The management interface can be a true OOBM interface or a standard interface functioning as the management interface. In either case, the management interface of the managed network element will be directly connected to the OOBM network.An OOBM interface does not forward transit traffic; thereby, providing complete separation of production and management traffic. Since all management traffic is immediately forwarded into the management network, it is not exposed to possible tampering. The separation also ensures that congestion or failures in the managed network do not affect the management of the device. If the device does not have an OOBM port, the interface functioning as the management interface must be configured so that management traffic does not leak into the managed network and that production traffic does not leak into the management network. ISL and 802.1q trunking enables multiple VLANs to traverse the same physical links between layer 2 switches or between a layer 2 switch and a router. If the management VLAN is not pruned from any VLAN trunk links belonging to the managed network’s infrastructure, management traffic has the potential to leak into the production network.

Check content

By default all the VLANs that exist on a switch are active on a trunk link. Since the switch is being managed via OOBM connection, management traffic should not traverse any trunk links.

Fix text

Prune the management VLAN from any VLAN trunk links belonging to the managed network’s infrastructure.

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