AC-3(3) - Access Enforcement | Mandatory Access Control

Enforce [Assignment: organization-defined mandatory access control policy] over the set of covered subjects and objects specified in the policy, and where the policy: (a) Is uniformly enforced across the covered subjects and objects within the system; (b) Specifies that a subject that has been granted access to information is constrained from doing any of the following; (1) Passing the information to unauthorized subjects or objects; (2) Granting its privileges to other subjects; (3) Changing one or more security attributes (specified by the policy) on subjects, objects, the system, or system components; (4) Choosing the security attributes and attribute values (specified by the policy) to be associated with newly created or modified objects; and (5) Changing the rules governing access control; and (c) Specifies that [Assignment: organization-defined subjects] may explicitly be granted [Assignment: organization-defined privileges] such that they are not limited by any defined subset (or all) of the above constraints.


ID: AC-3(3)
Enhancement of : AC-3

Space Segment Guidance

Non-discretionary (mandatory) access controls on a spacecraft are beneficial in segmenting mission-critical bus commands from payload-specific data flows. By assigning policy-based rules rather than relying solely on user- or process-driven choices, designers can ensure that, for example, a remote instrument's software cannot accidentally write to bus registers handling attitude control. Policy-based rules can also be instrumental in cross-domain scenarios, where specific payload data might be subject to higher classification than the spacecraft's housekeeping information. An effective mechanism might involve kernel-level or hardware-based partitions that label each data channel or subsystem with distinct security attributes. If the platform hosts multiple payloads with different security clearances, a robust mandatory access control scheme can prevent inadvertent "spillage" while preserving regular housekeeping and telemetry flows. While older satellites might lack the hardware-backed features needed, modern space designs increasingly adopt mandatory partitions or hypervisors that deliver strong data isolation. Properly configured, mandatory access control reduces the chance of cross-contamination from software faults or malicious payload behavior.