AC.L2-3.1.1
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Requirement
Limit system access to authorized users, processes acting on behalf of authorized users, and devices (including other systems).
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Discussion
Access control policies (e.g., identity- or role-based policies, control matrices, and cryptography) control access between active entities or subjects (i.e., users or processes acting on behalf of users) and passive entities or objects (e.g., devices, files, records, and domains) in systems. Access enforcement mechanisms can be employed at the application and service level to provide increased information security. Other systems include systems internal and external to the organization. This requirement focuses on account management for systems and applications. The definition of and enforcement of access authorizations, other than those determined by account type (e.g., privileged verses [sic] non-privileged) are addressed in requirement 3.1.2 (AC.L2-3.1.2).
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Further Discussion
Identify users, processes, and devices that are allowed to use company computers and can log on to the company network. Automated updates and other automatic processes should be associated with the user who initiated (authorized) the process. Limit the devices (e.g., printers) that can be accessed by company computers. Set up your system so that only authorized users, processes, and devices can access the company network.
This requirement, AC.L2-3.1.1, controls system access based on user, process, or device identity. AC.L2-3.1.1 leverages IA.L2-3.5.1 which provides a vetted and trusted identity for access control.
Example 1
Your company maintains a list of all personnel authorized to use company information systems, including those that store, process, and transmit CUI [a]. This list is used to support identification and authentication activities conducted by IT when authorizing access to systems [a,d].
Example 2
A coworker wants to buy a new multi-function printer/scanner/fax device and make it available on the company network within the CUI enclave. You explain that the company controls system and device access to the network and will prevent network access by unauthorized systems and devices [c]. You help the coworker submit a ticket that asks for the printer to be granted access to the network, and appropriate leadership approves the device [f].
Potential Assessment Considerations
- Is a list of authorized users maintained that defines their identities and roles [a]?
- Are account requests authorized before system access is granted [d,e,f]?
NIST 800-171A Assessment Guidance
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