Central Log Server Security Requirements Guide

To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DoD-approved PKIs, all DoD systems (e.g., networks, web servers, and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Access control policies include identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system. This requirement is applicable to access control enforcement applications (e.g., authentication servers) and other applications that perform information and system access control functions.

To assure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system. Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and any processes acting on behalf of users) must be uniquely identified and authenticated for all accesses.

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 and easily compromised. Use of passwords for authentication is intended only for limited situations and should not be used as a replacement for two-factor CAC-enabled authentication. Examples of situations where a user ID and password might be used include: - When the user does not use a CAC and is not a current DoD employee, member of the military, or DoD contractor. - When a user has been officially designated as temporarily unable to present a CAC for some reason (lost, damaged, not yet issued, broken card reader) (i.e., Temporary Exception User) and to satisfy urgent organizational needs must be temporarily permitted to use user ID/password authentication until the problem with CAC use has been remedied. - When the application is publicly available and or hosting publicly releasable data requiring some degree of need-to-know protection. If the password is already encrypted and not a plaintext password, this meets this requirement. Implementation of this requirement requires configuration of a FIPS-approved cipher block algorithm and block cipher modes for encryption. This method uses a one-way hashing encryption algorithm with a salt value to validate a user's password without having to store the actual password. Performance and time required to access are factors that must be considered, and the one-way hash is the most feasible means of securing the password and providing an acceptable measure of password security. Verifying the user knows a password is performed using a password verifier. In its simplest form, a password verifier is a computational function that is capable of creating a hash of a password and determining if the value provided by the user matches the hash. A more secure version of verifying a user knowing a password is to store the result of an iterating hash function and a large random salt value as follows: H0 = H(pwd, H(salt)) Hn = H(Hn-1,H(salt)) In the above, "n" is a cryptographically-strong random [*3] number. "Hn" is stored along with the salt. When the application wishes to verify that the user knows a password, it simply repeats the process and compares "Hn" with the stored "Hn". A salt is essentially a fixed-length cryptographically strong random value. Another method is using a keyed-hash message authentication code (HMAC). HMAC calculates a message authentication code via a cryptographic hash function used in conjunction with an encryption key. The key must be protected as with any private key.

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. 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. This requirement applies to all accounts, including authentication server; Authorization, Authentication, and Accounting (AAA); and local accounts such as the root account and the account of last resort. This requirement only applies to components where this is specific to the function of the device (e.g., TLS VPN or ALG). This does not apply to authentication for the purpose of configuring the device itself (management).

Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted. A trust anchor is an authoritative entity represented via a public key and associated data. It is used in the context of public key infrastructures, X.509 digital certificates, and DNSSEC. When there is a chain of trust, usually the top entity to be trusted becomes the trust anchor; it can be, for example, a Certification Authority (CA). A certification path starts with the subject certificate and proceeds through a number of intermediate certificates up to a trusted root certificate, typically issued by a trusted CA. This requirement verifies that a certification path to an accepted trust anchor is used to for certificate validation and that the path includes status information. Path validation is necessary for a relying party to make an informed trust decision when presented with any certificate not already explicitly trusted. Status information for certification paths includes certificate revocation lists or online certificate status protocol responses. Validation of the certificate status information is out of scope for this requirement.

If the private key is discovered, an attacker can use the key to authenticate as an authorized user and gain access to the network infrastructure. The cornerstone of the PKI is the private key used to encrypt or digitally sign information. If the private key is stolen, this will lead to the compromise of the authentication and non-repudiation gained through PKI because the attacker can use the private key to digitally sign documents and pretend to be the authorized user. Both the holders of a digital certificate and the issuing authority must protect the computers, storage devices, or whatever they use to keep the private keys.

To prevent the compromise of authentication information such as passwords during the authentication process, the feedback from the information system must not provide any information that would allow an unauthorized user to compromise the authentication mechanism. Obfuscation of user-provided information when typed into the system is a method used in addressing this risk. For example, displaying asterisks when a user types in a password is an example of obscuring feedback of authentication information.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection. To protect the integrity of the authenticator and authentication mechanism used for the cryptographic module used by the Central Log Server must be configured to use one of the following hash functions for hashing the password or other authenticator in accordance with SP 800-131Ar1: SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256, SHA3-224, SHA3-256, SHA3-384, and SHA3-512. Applications also include HMAC, KDFs, Random Bit Generation, and hash-only applications (e.g., hashing passwords and using SHA-1 or higher to compute a checksum). For digital signature verification, SP800-131Ar1 allows SHA-1 for legacy use where needed.

Without protection of the transmitted information, confidentiality and integrity may be compromised since unprotected communications can be intercepted and either read or altered. This requirement applies only to those applications that are either distributed or can allow access to data non-locally. Use of this requirement will be limited to situations where the data owner has a strict requirement for ensuring data integrity and confidentiality is maintained at every step of the data transfer and handling process. When transmitting data, applications need to leverage transmission protection mechanisms, such as TLS, SSL VPNs, or IPSEC. Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification. Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa.

FIPS 140-2 precludes the use of unvalidated cryptography for the cryptographic protection of sensitive or valuable data within Federal systems. Unvalidated cryptography is viewed by NIST as providing no protection to the information or data. In effect, the data would be considered unprotected plaintext. If the agency specifies that the information or data be cryptographically protected, then FIPS 140-2 is applicable. In essence, if cryptography is required, it must be validated. Cryptographic modules that have been approved for classified use may be used in lieu of modules that have been validated against the FIPS 140-2 standard.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection. To protect the integrity of the authenticator and authentication mechanism used for the cryptographic module used by the network device, the application, operating system, or protocol must be configured to use one of the following hash functions for hashing the password or other authenticator in accordance with SP 800-131Ar1: SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256, SHA3-224, SHA3-256, SHA3-384, and SHA3-512. For digital signature verification, SP800-131Ar1 allows SHA-1 for legacy use where needed.