F5 BIG-IP TMOS VPN Security Technical Implementation Guide

NIST cryptographic algorithms approved by NSA to protect NSS. Based on an analysis of the impact of quantum computing, cryptographic algorithms specified by CNSSP-15 and approved for use in products in the CSfC program, the approved algorithms have been changed to more stringent protocols configure with increased bit sizes and other secure characteristics to protect against quantum computing threats. The Commercial National Security Algorithm Suite (CNSA Suite) replaces Suite B.

Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-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 140-2/140-3 cryptographic module validation certificate as an approved security function, the algorithm implementation must meet all the requirements of FIPS 140-2/140-3 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.

Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. A block cipher mode is an algorithm that features the use of a symmetric key block cipher algorithm to provide an information service, such as confidentiality or authentication. AES is the FIPS-validated cipher block cryptographic algorithm approved for use in DOD. For an algorithm implementation to be listed on a FIPS 140-2/140-3 cryptographic module validation certificate as an approved security function, the algorithm implementation must meet all the requirements of FIPS 140-2/140-3 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.

Unrestricted traffic may contain malicious traffic which poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a network, which uses bandwidth and other resources. VPN traffic received from another enclave with different security policy or level of trust must not bypass be inspected by the firewall before being forwarded to the private network.

Without IKE, the SPI is manually specified for each security association. IKE peers will negotiate the encryption algorithm and authentication or hashing methods as well as generate the encryption keys. An IPsec SA is established using either IKE or manual configuration. When using IKE, the security associations are established when needed and expire after a period of time or volume of traffic threshold. If manually configured, they are established as soon as the configuration is complete at both end points and they do not expire. When using IKE, the Security Parameter Index (SPI) for each security association is a pseudo-randomly derived number. With manual configuration of the IPsec security association, both the cipher key and authentication key are static. Hence, if the keys are compromised, the traffic being protected by the current IPsec tunnel can be decrypted as well as traffic in any future tunnels established by this SA. Furthermore, the peers are not authenticated prior to establishing the SA, which could result in a rogue device establishing an IPsec SA with either of the VPN end points. IKE provides primary authentication to verify the identity of the remote system before negotiation begins. This feature is lost when the IPsec security associations are manually configured, which results in a nonterminating session using static pre-shared keys.

Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Use of passwords for authentication is intended only for limited situations and must not be used as a replacement for two-factor CAC-enabled authentication. 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 must not be configured to use SHA-2 for integrity of remote access sessions. The information system must specify the hash algorithm used for authenticating passwords. Implementation of this requirement requires configuration of FIPS-approved cipher block algorithm and block cipher modes for encryption. Pre-shared key cipher suites may only be used in networks where both the client and server belong to the same organization. Cipher suites using pre-shared keys must not be used with TLS 1.0 or 1.1 and must not be used with TLS 1.2 when a government client or server communicates with nongovernment systems.

Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data. The VPN gateway must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. NIST cryptographic algorithms approved by NSA to protect NSS. Based on an analysis of the impact of quantum computing, cryptographic algorithms specified by CNSSP-15 and approved for use in products in the CSfC program, the approved algorithms have been changed to more stringent protocols configure with increased bit sizes and other secure characteristics to protect against quantum computing threats. The Commercial National Security Algorithm Suite (CNSA Suite) replaces Suite B.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection. 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 must not be configured to use SHA-2 for integrity of remote access sessions. This requirement is applicable to the configuration of IKE Phase 1 and Phase 2.