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The Cisco VPN remote access server must be configured to use AES encryption for the Internet Key Exchange (IKE) Phase 1 to protect confidentiality of remote access sessions.


Finding ID Version Rule ID IA Controls Severity
V-239979 CASA-VN-000640 SV-239979r666343_rule High
Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DoD non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. AES is the FIPS-validated cipher block cryptographic algorithm approved for use in DoD. For an algorithm implementation to be listed on a FIPS 140-2 cryptographic module validation certificate as an approved security function, the algorithm implementation must meet all the requirements of FIPS 140-2 and must successfully complete the cryptographic algorithm validation process. Currently, NIST has approved the following confidentiality modes to be used with approved block ciphers in a series of special publications: ECB, CBC, OFB, CFB, CTR, XTS-AES, FF1, FF3, CCM, GCM, KW, KWP, and TKW.
Cisco ASA VPN Security Technical Implementation Guide 2021-08-16


Check Text ( C-43212r666341_chk )
Verify IKE Phase 1 is set to use an AES encryption algorithm as shown in the example below.

crypto ipsec ikev2 ipsec-proposal IPSEC_TRANS
protocol esp encryption aes-192

If the value of the encryption algorithm for IKE Phase 1 is not set to use an AES algorithm, this is a finding.
Fix Text (F-43171r666342_fix)
Configure the ASA to use AES encryption algorithm for IKE Phase 1 as shown in the example below.

ASA1(config)# crypto ikev2 policy 1
ASA1(config-ikev2-policy)# encryption aes-192