The Cisco ASA remote access VPN server must be configured to use SHA-2 at 384 bits 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-239978r916146_rule	CCI-001453	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 nonpublic 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			2024-08-22

Details

Check Text (C-239978r916146_chk)

Verify that the ASA uses SHA-2 at 384 bits 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 at 384 bits or greater is used for IKE Phase 1 as shown in the example below. crypto ikev2 policy 1 … … … integrity sha384 Step 2: Verify that SHA-2 at 384 bits or greater is used for the IPsec Security Association. crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS protocol esp integrity sha-384 If the ASA does not use SHA-2 at 384 bits or greater for hashing to protect the integrity of IPsec remote access sessions, this is a finding.

Fix Text (F-43170r916136_fix)

Configure the ASA to use SHA-2 at 384 bits 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 sha384 ASA1(config-ikev2-policy)# exit ASA1(config)# crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS ASA1(config-ipsec-proposal)# protocol esp integrity sha-384 ASA1(config-ikev2-policy)# end