The VPN gateway must use AES for IKE cryptographic encryption operations required to ensure privacy of the IKE session.

From IPSec VPN Gateway Security Technical Implementation Guide

Part of AES is not used for IKE encryption.

Associated with IA controls: ECSC-1

SV-40994r1_rule The VPN gateway must use AES for IKE cryptographic encryption operations required to ensure privacy of the IKE session.

Vulnerability discussion

While there is much debate about the security and performance of Advance Encryption Standard (AES), there is a consensus that it is significantly more secure than any of the algorithms supported by IPSec implementations today. AES is available in three key sizes: 128, 192 and 256 bits, versus the 56 bit DES. Therefore, there are approximately 1021 times more AES 128-bit keys than DES 56-bit keys. In addition, AES uses a block size of 128 bits—twice the size of DES or 3DES. To ensure the privacy of the IKE session responsible for establishing the security association and key exchange for an IPSec tunnel, it is imperative that AES is used for encryption operations.

Check content

Examine all ISAKMP policies configured on the VPN gateway to determine what encryption algorithm is being used for establishing an IKE Security Association.

Fix text

Configure all ISAKMP policies to use AES for IKE cryptographic encryption operations.

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