The Cisco router must be configured to enforce approved authorizations for controlling the flow of management information within the device based on control policies.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-96023	CISC-ND-000140	SV-105161r1_rule		Medium

Description
A mechanism to detect and prevent unauthorized communication flow must be configured or provided as part of the system design. If management information flow is not enforced based on approved authorizations, the network device may become compromised. Information flow control regulates where management information is allowed to travel within a network device. The flow of all management information must be monitored and controlled so it does not introduce any unacceptable risk to the network device or data. Application-specific examples of enforcement occur in systems that employ rule sets or establish configuration settings that restrict information system services or message-filtering capability based on message content (e.g., implementing key word searches or using document characteristics). Applications providing information flow control must be able to enforce approved authorizations for controlling the flow of management information within the system in accordance with applicable policy.

Description

A mechanism to detect and prevent unauthorized communication flow must be configured or provided as part of the system design. If management information flow is not enforced based on approved authorizations, the network device may become compromised. Information flow control regulates where management information is allowed to travel within a network device. The flow of all management information must be monitored and controlled so it does not introduce any unacceptable risk to the network device or data. Application-specific examples of enforcement occur in systems that employ rule sets or establish configuration settings that restrict information system services or message-filtering capability based on message content (e.g., implementing key word searches or using document characteristics). Applications providing information flow control must be able to enforce approved authorizations for controlling the flow of management information within the system in accordance with applicable policy.

STIG	Date
Cisco IOS Router NDM Security Technical Implementation Guide	2019-12-19

Details

Check Text ( C-94855r1_chk )
Review the Cisco router configuration to verify that it is compliant with this requirement. Step 1: Verify that the line vty has an ACL inbound applied as shown in the example below. line vty 0 4 access-class MANAGEMENT_NET in transport input ssh Step 2: Verify that the ACL permits only hosts from the management network to access the router. ip access-list standard MANAGEMENT_NET permit x.x.x.0 0.0.0.255 If the Cisco router is not configured to enforce approved authorizations for controlling the flow of management information within the device based on control policies, this is a finding.

Check Text ( C-94855r1_chk )

Review the Cisco router configuration to verify that it is compliant with this requirement.

Step 1: Verify that the line vty has an ACL inbound applied as shown in the example below.

line vty 0 4
access-class MANAGEMENT_NET in
transport input ssh

Step 2: Verify that the ACL permits only hosts from the management network to access the router.

ip access-list standard MANAGEMENT_NET
permit x.x.x.0 0.0.0.255

If the Cisco router is not configured to enforce approved authorizations for controlling the flow of management information within the device based on control policies, this is a finding.

Fix Text (F-101701r1_fix)
Configure the Cisco router to restrict management access to specific IP addresses via SSH as shown in the example below. R2(config)#ip access-list standard MANAGEMENT_NET R2(config-std-nacl)#permit x.x.x.0 0.0.0.255 R2(config-std-nacl)#exit R2(config)#line vty 0 4 R2(config-line)#transport input ssh R2(config-line)#access-class MANAGEMENT_NET in R2(config-line)#end