The Cisco perimeter switch must be configured to have Cisco Discovery Protocol (CDP) disabled on all external interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-221097	CISC-RT-000370	SV-221097r622190_rule		Low

Description
CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP is media-and-protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing CDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack.

Description

CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP is media-and-protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing CDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack.

STIG	Date
Cisco NX-OS Switch RTR Security Technical Implementation Guide	2021-03-29

Details

Check Text ( C-22812r409780_chk )
Step 1: Verify CDP is not enabled globally via the command no cdp enable By default CDP is enabled globally; hence, the command cdp enable will not be shown in the configuration. If CDP is enabled, proceed to Step 2. Step 2: Verify CDP is not enabled on any external interface as shown in the example below: interface Ethernet2/2 description link to DISN no switchport no cdp enable Note: By default CDP is enabled on all interfaces if CDP is enabled globally. If CDP is enabled on any external interface, this is a finding.

Check Text ( C-22812r409780_chk )

Step 1: Verify CDP is not enabled globally via the command no cdp enable

By default CDP is enabled globally; hence, the command cdp enable will not be shown in the configuration. If CDP is enabled, proceed to Step 2.

Step 2: Verify CDP is not enabled on any external interface as shown in the example below:

interface Ethernet2/2
description link to DISN
no switchport
no cdp enable

Note: By default CDP is enabled on all interfaces if CDP is enabled globally.

If CDP is enabled on any external interface, this is a finding.

Fix Text (F-22801r409781_fix)
Disable CDP on all external interfaces via no cdp enable interface command or disable CDP globally via no cdp enable command.