CASA-VN-000240 - The Cisco ASA must be configured to use FIPS-validated SHA-2 or higher for Internet Key Exchange (IKE) Phase 2 - proposal
Authenticity protection provides protection against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. Although allowed by SP800-131Ar2 for some applications, SHA-1 is considered a compromised hashing standard and is being phased out of use by industry and Government standards. Unless required for legacy use, DoD systems should not be configured to use SHA-2 for integrity of remote access sessions. This requirement focuses on communications protection for the application session rather than for the network packet and establishes grounds for confidence at both ends of communications sessions in ongoing identities of other parties and in the validity of information transmitted. Depending on the required degree of confidentiality and integrity, web services/SOA will require the use of mutual authentication (two-way/bidirectional). An IPsec Security Association (SA) is established using either IKE or manual configuration.
Configure the ASA to use FIPS-validated SHA-2 or higher for IKE Phase 2. Step 1: Configure the IKE Phase 2 proposal as shown in the example below. ASA1(config)# crypto ipsec ikev2 ipsec-proposal AES_SHA ASA1(config-ipsec-proposal)# protocol esp integrity sha-384 sha-256 ASA1(config-ipsec-proposal)# exit Step 2: Configure the crypto map using the configured proposal. ASA1(config)# crypto map IPSEC_MAP 10 set ikev2 ipsec-proposal ASA1(config)# end