The Cisco ASA remote access VPN server must be configured to use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-239978	CASA-VN-000630	SV-239978r769254_rule		Medium

Description
Without strong cryptographic integrity protections, information can be altered by unauthorized users without detection. SHA-1 is considered a compromised hashing standard and is being phased out of use by industry and Government standards. DoD systems must not be configured to use SHA-1 for integrity of remote access sessions. The remote access VPN provides access to DoD non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network.

Description

Without strong cryptographic integrity protections, information can be altered by unauthorized users without detection. SHA-1 is considered a compromised hashing standard and is being phased out of use by industry and Government standards. DoD systems must not be configured to use SHA-1 for integrity of remote access sessions. The remote access VPN provides access to DoD non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network.

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

Details

Check Text ( C-43211r666338_chk )
Verify the ASA SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions as shown in the example below. Step 1: Verify that SHA-2 or greater is used for IKE Phase 1 as shown in the example below. crypto ikev2 policy 1 … … … integrity sha256 Step 2: Verify that SHA-2 or greater is used for the IPsec Security Association. crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS protocol esp integrity sha-256 If the ASA does not use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions, this is a finding.

Check Text ( C-43211r666338_chk )

Verify the ASA SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions as shown in the example below.

Step 1: Verify that SHA-2 or greater is used for IKE Phase 1 as shown in the example below.

crypto ikev2 policy 1
…
…
…
integrity sha256

Step 2: Verify that SHA-2 or greater is used for the IPsec Security Association.

crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS
protocol esp integrity sha-256

If the ASA does not use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions, this is a finding.

Fix Text (F-43170r666339_fix)
Configure the ASA to use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions as shown in the example below. ASA1(config)# crypto ikev2 policy 1 ASA1(config-ikev2-policy)# integrity sha256 ASA1(config-ikev2-policy)# exit ASA1(config)# crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS ASA1(config-ipsec-proposal)# protocol esp integrity sha-256 ASA1(config-ikev2-policy)# end

Fix Text (F-43170r666339_fix)

Configure the ASA to use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions as shown in the example below.

ASA1(config)# crypto ikev2 policy 1
ASA1(config-ikev2-policy)# integrity sha256
ASA1(config-ikev2-policy)# exit
ASA1(config)# crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS
ASA1(config-ipsec-proposal)# protocol esp integrity sha-256
ASA1(config-ikev2-policy)# end