The gateway router for the managed network is not configured with an ACL or filter on the egress interface to block all outbound management traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17829	NET1000	SV-19317r2_rule	ECSC-1	Medium

Description
The management network must still have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes such as routers and firewalls. Management traffic between the managed network elements and the management network is routed via the same links and nodes as that used for production or operational traffic. Safeguards must be implemented to ensure that the management traffic does not leak past the managed network’s premise equipment such as using egress ACLs.

Description

The management network must still have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes such as routers and firewalls. Management traffic between the managed network elements and the management network is routed via the same links and nodes as that used for production or operational traffic. Safeguards must be implemented to ensure that the management traffic does not leak past the managed network’s premise equipment such as using egress ACLs.

STIG	Date
Perimeter Router Security Technical Implementation Guide Cisco	2017-03-09

Details

Check Text ( C-20266r1_chk )
The gateway router of the managed network must be configured with an ACL or filter on the egress interface to block all outbound management traffic. Review router configuration to verify that any traffic destined to the management network is blocked. The configuration example below is blocking all traffic with a destination address from the 10/8 prefix which is being used as the address block for the management network. IOS interface Serial0/0 description to_NIPRNet ip address 188.1.20.3 255.255.255.0 ip access-group 100 in ip access-group 101 out interface Fastethernet 0/0 description to_our_PrivateNet ip address 192.168.1.1 255.255.255.0 ! access-list 101 deny ip any 10.0.0.0 0.255.255.255 log access-list 101 permit ip … … access-list 101 deny ip any any log

Check Text ( C-20266r1_chk )

The gateway router of the managed network must be configured with an ACL or filter on the egress interface to block all outbound management traffic.

Review router configuration to verify that any traffic destined to the management network is blocked. The configuration example below is blocking all traffic with a destination address from the 10/8 prefix which is being used as the address block for the management network.

IOS

interface Serial0/0
description to_NIPRNet
ip address 188.1.20.3 255.255.255.0
ip access-group 100 in
ip access-group 101 out
interface Fastethernet 0/0
description to_our_PrivateNet
ip address 192.168.1.1 255.255.255.0
!
access-list 101 deny ip any 10.0.0.0 0.255.255.255 log
access-list 101 permit ip …
…
access-list 101 deny ip any any log

Fix Text (F-17746r1_fix)
Configure the gateway router of the managed network with an ACL or filter on the egress interface to block all outbound management traffic.