3.13.3Separate admin interfaces from user interfaces in Rev. 3

This requirement focuses on account management for systems and applications. The definition and enforcement of access authorizations other than those determined by account type (e.g., privileged access, non-privileged access) are addressed in <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.01.02">03.01.02</a>. System account types include individual, group, temporary, system, guest, anonymous, emergency, developer, and service. Users who require administrative privileges on system accounts receive additional scrutiny by personnel responsible for approving such accounts and privileged access. Types of accounts that organizations may prohibit due to increased risk include group, emergency, guest, anonymous, and temporary. Organizations may choose to define access privileges or other attributes by account, type of account, or a combination of both. Other attributes required for authorizing access include restrictions on the time of day, day of the week, and point of origin. When defining other system account attributes, organizations consider system requirements (e.g., system upgrades, scheduled maintenance) and mission and business requirements (e.g., time zone differences, remote access to facilitate travel requirements). Users who pose a significant security risk include individuals for whom reliable evidence indicates either the intention to use authorized access to the system to cause harm or that adversaries will cause harm through them. Close coordination among mission and business owners, system administrators, human resource managers, and legal staff is essential when disabling system accounts for high-risk individuals. Time periods for the notification of organizational personnel or roles may vary. Inactivity logout is behavior- or policy-based and requires users to take physical action to log out when they are expecting inactivity longer than the defined period. Automatic enforcement of inactivity logout is addressed by <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.01.10">03.01.10</a>.

Access control policies control access between active entities or subjects (i.e., users or system processes acting on behalf of users) and passive entities or objects (i.e., devices, files, records, domains) in organizational systems. Types of system access include remote access and access to systems that communicate through external networks, such as the internet. Access enforcement mechanisms can also be employed at the application and service levels to provide increased protection for CUI. This recognizes that the system can host many applications and services in support of mission and business functions. Access control policies are defined in <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.15.01">03.15.01</a>.

Information flow control regulates where CUI can transit within a system and between systems (in contrast to who is allowed to access the information) and without regard to subsequent accesses to that information. Flow control restrictions include keeping CUI from being transmitted in the clear to the internet, blocking external communications traffic that claims to be sourced from within the organization, restricting requests to the internet that are not from the internal web proxy server, and limiting CUI transfers between organizations based on data structures and content. Transferring CUI between organizations may require an agreement that specifies how the information flow is enforced (see <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.12.05">03.12.05</a>). Transferring CUI between systems that represent different security domains with different security policies introduces the risk that such transfers violate one or more domain security policies. In such situations, information owners or stewards provide guidance at designated policy enforcement points between interconnected systems. Organizations consider mandating specific architectural solutions when required to enforce specific security policies. Enforcement includes prohibiting CUI transfers between interconnected systems (i.e., allowing information access only), employing hardware mechanisms to enforce one-way information flows, and implementing trustworthy regrading mechanisms to reassign security attributes and security labels. Organizations commonly use information flow control policies and enforcement mechanisms to control the flow of CUI between designated sources and destinations (e.g., networks, individuals, and devices) within systems and between interconnected systems. Flow control is based on characteristics of the information or the information path. Enforcement occurs in boundary protection devices (e.g., encrypted tunnels, routers, gateways, and firewalls) that use rule sets or establish configuration settings that restrict system services, provide a packet-filtering capability based on header information, or provide a message-filtering capability based on message content (e.g., implementing key word searches or using document characteristics). Organizations also consider the trustworthiness of filtering and inspection mechanisms (i.e., hardware, firmware, and software components) that are critical to information flow enforcement.

Separation of duties addresses the potential for abuse of authorized privileges and reduces the risk of malevolent activity without collusion. Separation of duties includes dividing mission functions and support functions among different individuals or roles, conducting system support functions with different individuals or roles (e.g., quality assurance, configuration management, network security, system management, assessments, and programming), and ensuring that personnel who administer access control functions do not also administer audit functions. Because separation of duty violations can span systems and application domains, organizations consider the entirety of their systems and system components when developing policies on separation of duties. This requirement is enforced by <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.01.02">03.01.02</a>.

Organizations employ the principle of least privilege for specific duties and authorized access for users and system processes. Least privilege is applied to the development, implementation, and operation of the system. Organizations consider creating additional processes, roles, and system accounts to achieve least privilege. Security functions include establishing system accounts and assigning privileges, installing software, configuring access authorizations, configuring settings for events to be audited, establishing vulnerability scanning parameters, establishing intrusion detection parameters, and managing audit information. Security-relevant information includes threat and vulnerability information, filtering rules for routers or firewalls, configuration parameters for security services, security architecture, cryptographic key management information, access control lists, and audit information.

Privileged accounts refer to accounts that are granted elevated privileges to access resources (including security functions or security-relevant information) that are otherwise restricted for non-privileged accounts. These accounts are typically described as system administrator or super user accounts. For example, a privileged account is often required in order to perform privileged functions such as executing commands that could modify system behavior. Restricting privileged accounts to specific personnel or roles ensures that only those authorized users can access and manipulate security functions or security-relevant information. Requiring the use of non-privileged accounts when such access is not needed can limit unauthorized access to and manipulation of security functions or security-relevant information.

Privileged functions include establishing system accounts, performing system integrity checks, conducting patching operations, changing system configuration settings, or administering cryptographic key management activities. Non-privileged users do not possess the authorizations to execute privileged functions. Bypassing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users. This requirement represents a condition achieved by the definition of authorized privileges in <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.01.01">03.01.01</a> and privilege enforcement in <a href="#/cprt/framework/version/SP_800_171_3_0_0/home?element=03.01.02">03.01.02</a>. The misuse of privileged functions — whether intentionally or unintentionally by authorized users or by unauthorized external entities that have compromised system accounts — is a serious and ongoing concern that can have significant adverse impacts on organizations. Logging the use of privileged functions is one way to detect such misuse and mitigate risks from advanced persistent threats and insider threats.