The Cisco perimeter switch must be configured to block all outbound management traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-221019	CISC-RT-000390	SV-221019r622190_rule		Medium

Description
For in-band management, the management network must have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes, such as switches 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 perimeter of the managed network.

Description

For in-band management, the management network must have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes, such as switches 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 perimeter of the managed network.

STIG	Date
Cisco IOS-XE Switch RTR Security Technical Implementation Guide	2021-03-26

Details

Check Text ( C-22734r408851_chk )
The perimeter switch of the managed network must be configured with an outbound ACL on the egress interface to block all management traffic as shown in the example below: Step 1: Verify that all external interfaces has been configured with an outbound ACL as shown in the example below: interface GigabitEthernet0/2 description link to DISN ip address x.11.1.2 255.255.255.254 ip access-group EXTERNAL_ACL_OUTBOUND out Step 2: Verify that the outbound ACL discards management traffic as shown in the example below: ip access-list extended EXTERNAL_ACL_OUTBOUND deny tcp any any eq tacacs log-input deny tcp any any eq 22 log-input deny udp any any eq snmp log-input deny udp any any eq snmptrap log-input deny udp any any eq syslog log-input permit tcp any any eq www log-input deny ip any any log-input If management traffic is not blocked at the perimeter, this is a finding.

Check Text ( C-22734r408851_chk )

The perimeter switch of the managed network must be configured with an outbound ACL on the egress interface to block all management traffic as shown in the example below:

Step 1: Verify that all external interfaces has been configured with an outbound ACL as shown in the example below:

interface GigabitEthernet0/2
description link to DISN
ip address x.11.1.2 255.255.255.254
ip access-group EXTERNAL_ACL_OUTBOUND out

Step 2: Verify that the outbound ACL discards management traffic as shown in the example below:

ip access-list extended EXTERNAL_ACL_OUTBOUND
deny tcp any any eq tacacs log-input
deny tcp any any eq 22 log-input
deny udp any any eq snmp log-input
deny udp any any eq snmptrap log-input
deny udp any any eq syslog log-input
permit tcp any any eq www log-input
deny ip any any log-input

If management traffic is not blocked at the perimeter, this is a finding.

Fix Text (F-22723r408852_fix)
Configure the perimeter switch of the managed network with an outbound ACL on the egress interface to block all management traffic. Step 1: Configure an ACL to block egress management traffic. SW1(config)#ip access-list extended EXTERNAL_ACL_OUTBOUND SW1(config-ext-nacl)#deny tcp any any eq tacacs log-input SW1(config-ext-nacl)#deny tcp any any eq 22 log-input SW1(config-ext-nacl)#deny udp any any eq snmp log-input SW1(config-ext-nacl)#deny udp any any eq snmptrap log-input SW1(config-ext-nacl)#deny udp any any eq syslog log-input SW1(config-ext-nacl)#permit tcp any any eq www SW1(config-ext-nacl)#deny ip any any log-input SW1(config-ext-nacl)#exit Note: Permit commands would be configured to allow applicable outbound traffic. The example above is allowing web traffic. Step 2: Configure the external interfaces with the outbound ACL. SW1(config)#int g0/2 SW1(config-if)#ip access-group EXTERNAL_ACL_OUTBOUND out

Fix Text (F-22723r408852_fix)

Configure the perimeter switch of the managed network with an outbound ACL on the egress interface to block all management traffic.

Step 1: Configure an ACL to block egress management traffic.

SW1(config)#ip access-list extended EXTERNAL_ACL_OUTBOUND
SW1(config-ext-nacl)#deny tcp any any eq tacacs log-input
SW1(config-ext-nacl)#deny tcp any any eq 22 log-input
SW1(config-ext-nacl)#deny udp any any eq snmp log-input
SW1(config-ext-nacl)#deny udp any any eq snmptrap log-input
SW1(config-ext-nacl)#deny udp any any eq syslog log-input
SW1(config-ext-nacl)#permit tcp any any eq www
SW1(config-ext-nacl)#deny ip any any log-input
SW1(config-ext-nacl)#exit

Note: Permit commands would be configured to allow applicable outbound traffic. The example above is allowing web traffic.

Step 2: Configure the external interfaces with the outbound ACL.

SW1(config)#int g0/2
SW1(config-if)#ip access-group EXTERNAL_ACL_OUTBOUND out