An inbound ACL is not configured for the management network sub-interface of the trunk link to block non-management traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17834	NET1005	SV-19308r1_rule		Medium

Description
If the management systems reside within the same layer 2 switching domain as the managed network elements, then separate VLANs will be deployed to provide separation at that level. In this case, the management network still has its own subnet while at the same time it is defined as a unique VLAN. Inter-VLAN routing or the routing of traffic between nodes residing in different subnets requires a router or multi-layer switch (MLS). Access control lists must be used to enforce the boundaries between the management network and the network being managed. All physical and virtual (i.e. MLS SVI) routed interfaces must be configured with ACLs to prevent the leaking of unauthorized traffic from one network to the other.

Description

If the management systems reside within the same layer 2 switching domain as the managed network elements, then separate VLANs will be deployed to provide separation at that level. In this case, the management network still has its own subnet while at the same time it is defined as a unique VLAN. Inter-VLAN routing or the routing of traffic between nodes residing in different subnets requires a router or multi-layer switch (MLS). Access control lists must be used to enforce the boundaries between the management network and the network being managed. All physical and virtual (i.e. MLS SVI) routed interfaces must be configured with ACLs to prevent the leaking of unauthorized traffic from one network to the other.

STIG	Date
Infrastructure Router Security Technical Implementation Guide Cisco	2018-11-27

Details

Check Text ( C-20257r1_chk )
Review the router configuration and verify that an inbound ACL has been configured for the management network sub-interface as illustrated in the following example configuration: IOS interface GigabitEthernet3 no ip redirects no ip directed-broadcast interface GigabitEthernet3.10 encapsulation dot1q 10 description Management VLAN ip address 10.1.1.1 255.255.255.0 ip access-group 108 in ! access-list 108 permit …

Check Text ( C-20257r1_chk )

Review the router configuration and verify that an inbound ACL has been configured for the management network sub-interface as illustrated in the following example configuration:

IOS

interface GigabitEthernet3
no ip redirects
no ip directed-broadcast
interface GigabitEthernet3.10
encapsulation dot1q 10
description Management VLAN
ip address 10.1.1.1 255.255.255.0
ip access-group 108 in
!
access-list 108 permit …

Fix Text (F-17751r1_fix)
If a router is used to provide inter-VLAN routing, configure an inbound ACL for the management network sub-interface for the trunk link to block non-management traffic.