The Cisco ASA remote access VPN server must be configured to use LDAP over SSL to determine authorization for granting access to the network.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-239966	CASA-VN-000400	SV-239966r666304_rule		Medium

Description
Protecting authentication communications between the client, the VPN Gateway, and the authentication server keeps this critical information from being exploited. In distributed information systems, authorization processes and access control decisions may occur in separate parts of the systems. In such instances, authorization information is transmitted securely so timely access control decisions can be enforced at the appropriate locations. To support the access control decisions, it may be necessary to transmit as part of the access authorization information, supporting security attributes. This is due to the fact that in distributed information systems, there are various access control decisions that need to be made and different entities (e.g., services) make these decisions in a serial fashion, each requiring some security attributes to make the decisions. This applies to VPN gateways that have the concept of a user account and have the login function residing on the VPN gateway.

Description

Protecting authentication communications between the client, the VPN Gateway, and the authentication server keeps this critical information from being exploited. In distributed information systems, authorization processes and access control decisions may occur in separate parts of the systems. In such instances, authorization information is transmitted securely so timely access control decisions can be enforced at the appropriate locations. To support the access control decisions, it may be necessary to transmit as part of the access authorization information, supporting security attributes. This is due to the fact that in distributed information systems, there are various access control decisions that need to be made and different entities (e.g., services) make these decisions in a serial fashion, each requiring some security attributes to make the decisions. This applies to VPN gateways that have the concept of a user account and have the login function residing on the VPN gateway.

STIG	Date
Cisco ASA VPN Security Technical Implementation Guide	2021-08-16

Details

Check Text ( C-43199r666302_chk )
Step 1: Verify that authorization is enforced as shown in the example below. tunnel-group ANY_CONNECT type remote-access tunnel-group ANY_CONNECT general-attributes authorization-server-group LDAP authorization-required Step 2: Verify that LDAP over SSL has been enabled. aaa-server LDAP protocol ldap aaa-server LDAP (INSIDE) host 10.1.1.1 ldap-over-ssl enable If the ASA is not configured to use LDAP over SSL to determine authorization for granting access to the network, this is a finding.

Check Text ( C-43199r666302_chk )

Step 1: Verify that authorization is enforced as shown in the example below.

tunnel-group ANY_CONNECT type remote-access
tunnel-group ANY_CONNECT general-attributes
authorization-server-group LDAP
authorization-required

Step 2: Verify that LDAP over SSL has been enabled.

aaa-server LDAP protocol ldap
aaa-server LDAP (INSIDE) host 10.1.1.1
ldap-over-ssl enable

If the ASA is not configured to use LDAP over SSL to determine authorization for granting access to the network, this is a finding.

Fix Text (F-43158r666303_fix)
Step 1: Configure the ASA to use LDAP over SSL as shown in the example below. ASA2(config)# aaa-server LDAP protocol ldap ASA2(config)# aaa-server LDAP (INSIDE) host 10.1.1.1 ASA2(config-aaa-server-host)# ldap-over-ssl enable ASA2(config-aaa-server-host)# exit Step 2: Configure the ASA to enforce authorization using the common name (CN) from the user’s certificate. ASA2(config)# tunnel-group ANY_CONNECT general-attributes ASA2(config-tunnel-general)# authorization-required ASA2(config-tunnel-general)# authorization-server-group LDAP ASA2(config-tunnel-general)# end

Fix Text (F-43158r666303_fix)

Step 1: Configure the ASA to use LDAP over SSL as shown in the example below.

ASA2(config)# aaa-server LDAP protocol ldap
ASA2(config)# aaa-server LDAP (INSIDE) host 10.1.1.1
ASA2(config-aaa-server-host)# ldap-over-ssl enable
ASA2(config-aaa-server-host)# exit

Step 2: Configure the ASA to enforce authorization using the common name (CN) from the user’s certificate.

ASA2(config)# tunnel-group ANY_CONNECT general-attributes
ASA2(config-tunnel-general)# authorization-required
ASA2(config-tunnel-general)# authorization-server-group LDAP
ASA2(config-tunnel-general)# end