HPE Aruba Networking AOS NDM Security Technical Implementation Guide

Successful identification and authentication must not automatically give an entity full access to a network device or security domain. The lack of authorization-based access control could result in the immediate compromise and unauthorized access to sensitive information. All DOD systems must be properly configured to incorporate access control methods that do not rely solely on authentication for authorized access. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset or set of resources. Information systems use access control policies and enforcement mechanisms to implement this requirement. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Some network devices are preconfigured with security groups. Other network devices enable operators to create custom security groups with custom permissions. For example, an information system security manager (ISSM) may require read-only access to audit the network device. Operators may create an audit security group, define permissions and access levels for members of the group, and then assign the ISSM's user persona to the audit security group. This is still considered privileged access, but the ISSM's security group is more restrictive than the network administrator's security group. Network devices that rely on authentication, authorization, and accounting (AAA) brokers for authentication and authorization services may need to identify the available security groups or access levels available on the network devices and convey that information to the AAA operator. Once the AAA broker identifies the user persona on the centralized directory service, the user's security group memberships can be retrieved. The AAA operator may need to create a mapping that links target security groups from the directory service to the appropriate security groups or access levels on the network device. Once these mappings are configured, authorizations can happen dynamically based on each user's directory service group membership.

To prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable unused or unnecessary physical and logical ports/protocols on information systems. Network devices are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., email and web services); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the network device must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved. Some network devices have capabilities enabled by default; if these capabilities are not necessary, they must be disabled. If a particular capability is used, it must be documented and approved.

MFA is when two or more factors are used to confirm the identity of an individual who is requesting access to digital information resources. Valid factors include something the individual knows (e.g., username and password), something the individual has (e.g., a smart card or token), or something the individual is (e.g., a fingerprint or biometric). Legacy information system environments only use a single factor for authentication, typically a username and password combination. Although two pieces of data are used in a username and password combination, this is still considered single factor because an attacker can obtain access by learning what the user knows. Common attacks against single-factor authentication are attacks on user passwords. These attacks include brute force password guessing, password spraying, and password credential stuffing. MFA, along with strong user account hygiene, helps mitigate the threat of having account passwords discovered by an attacker. Even in the event of a password compromise, with MFA implemented and required for interactive login, the attacker still needs to acquire something the user has or replicate a piece of the user's biometric digital presence. Private industry recognizes and uses a wide variety of MFA solutions. However, DOD PKI is the only prescribed method approved for DOD organizations to implement MFA. For authentication purposes, centralized DOD certificate authorities (CA) issue PKI certificate key pairs (public and private) to individuals using the prescribed x.509 format. The private certificates that have been generated by the issuing CA are downloaded and saved to smart cards which, within DOD, are referred to as common access cards (CAC) or personal identity verification (PIV) cards. This happens at designated DOD badge facilities. The CA maintains a record of the corresponding public keys for use with PKI-enabled environments. Privileged user smart cards, or "alternate tokens", function in the same manner, so this requirement applies to all interactive user sessions (authorized and privileged users). Note: This requirement is used in conjunction with a centralized authentication server (e.g., Authentication, Authorization, and Accounting [AAA], Remote Authentication Dial-In User Service [RADIUS], Lightweight Directory Access Protocol [LDAP]), a separate but equally important requirement. The MFA configuration of this requirement provides identification and the first phase of authentication (the challenge and validated response, thereby confirming the PKI certificate that was presented by the user). The centralized authentication server will provide the second phase of authentication (the digital presence of the PKI ID as a valid user in the requested security domain) and authorization. The centralized authentication server will map validated PKI identities to valid user accounts and determine access levels for authenticated users based on security group membership and role. In cases where the centralized authentication server is not used by the network device for user authorization, the network device must map the authenticated identity to the user account for PKI-based authentication. Satisfies: SRG-APP-000149-NDM-000247, SRG-APP-000080-NDM-000220, SRG-APP-000153-NDM-000249, SRG-APP-000177-NDM-000263

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. Network devices can accomplish this by making direct function calls to encryption modules or by leveraging operating system encryption capabilities.

Once issued by a DOD certificate authority (CA), PKI certificates are typically valid for three years or less within the DOD. However, there are many reasons a certificate may become invalid before the prescribed expiration date. For example, an employee may leave or be terminated and still possess the smartcard on which the PKI certificates were stored. Another example is that a smartcard containing PKI certificates may become lost or stolen. A more serious issue could be that the CA or server that issued the PKI certificates has become compromised, thereby jeopardizing every certificate keypair that was issued by the CA. These examples of revocation use cases and many more can be researched further using internet cybersecurity resources. PKI user certificates presented as part of the identification and authentication criteria (e.g., DOD PKI as multifactor authentication [MFA]) must be checked for validity by network devices. For example, valid PKI certificates are digitally signed by a trusted DOD CA. Additionally, valid PKI certificates are not expired, and valid certificates have not been revoked by a DOD CA. Network devices can verify the validity of PKI certificates by checking with an authoritative CA. One method of checking the status of PKI certificates is to query databases referred to as CRLs. These are lists that are published, updated, and maintained by authoritative DOD CAs. For example, once certificates are expired or revoked, issuing CAs place the certificates on a CRL. Organizations can download these lists periodically (i.e., daily or weekly) and store them locally on the devices themselves or onto another nearby local enclave resource. Storing them locally ensures revocation status can be checked even if internet connectivity is severed at the enclave's point of presence. However, CRLs can be large in storage size, and the use of CRLs can tax some computing resources. Another method of validating certificate status is to use the OCSP. Using OCSP, a requestor (i.e., the network device the user is trying to authenticate to) sends a request to an authoritative CA challenging the validity of a certificate that has been presented for identification and authentication. The CA receives the request and sends a digitally signed response indicating the status of the user's certificate as valid, revoked, or unknown. Network devices should only allow access for responses that indicate the certificates presented by the user were considered valid by an approved DOD CA. OCSP is the preferred method because it is fast, provides the most current status, and is lightweight.

Unapproved mechanisms that are used for authentication to the cryptographic module are not validated and therefore cannot be relied on to provide confidentiality or integrity, and DOD data may be compromised. Network devices using encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-2/140-3 is the current standard for validating that mechanisms used to access cryptographic modules use authentication that meets DOD requirements. However, authentication algorithms must configure security processes to use only authentication algorithms that are FIPS-approved and recommended by the National Institute of Standards and Technology (NIST). Satisfies: SRG-APP-000179-NDM-000265, SRG-APP-000224-NDM-000270, SRG-APP-000411-NDM-000330, SRG-APP-000412-NDM-000331

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. Quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated Transmission Control Protocol/Internet Protocol (TCP/IP) address/port pairs at the operating system level or deallocating networking assignments at the application level if multiple application sessions are using a single, operating system-level network connection. This does not mean that the device terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session. Satisfies: SRG-APP-000190-NDM-000267, SRG-APP-000186-NDM-000266

Centralized management of authentication settings increases the security of remote and nonlocal access methods. This control is particularly important protection against the insider threat. With robust centralized management, audit records for administrator account access to the organization's network devices can be more readily analyzed for trends and anomalies. The alternative method of defining administrator accounts on each device exposes the device configuration to remote access authentication attacks and system administrators with multiple authenticators for each network device.

The aggregation of log data kept on a syslog server can be used to detect attacks and trigger an alert to the appropriate security personnel. The stored log data can be used to detect weaknesses in security that enable the network Information Assurance team to find and address these weaknesses before breaches can occur. Reviewing these logs, whether before or after a security breach, is important to learn whether someone is an internal employee or an outside threat. Satisfies: SRG-APP-000516-NDM-000350, SRG-APP-000223-NDM-000269