SC-4

SC-4 INFORMATION IN SHARED RESOURCES

Overview

Number	Title	Impact	Priority	Subject Area
SC-4	Information In Shared Resources	MODERATE	P1	System And Communications Protection

Instructions
The information system prevents unauthorized and unintended information transfer via shared system resources.

Guidance
This control prevents information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This control does not address: (i) information remanence which refers to residual representation of data that has been nominally erased or removed; (ii) covert channels (including storage and/or timing channels) where shared resources are manipulated to violate information flow restrictions; or (iii) components within information systems for which there are only single users/roles.

Guidance

This control prevents information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This control does not address: (i) information remanence which refers to residual representation of data that has been nominally erased or removed; (ii) covert channels (including storage and/or timing channels) where shared resources are manipulated to violate information flow restrictions; or (iii) components within information systems for which there are only single users/roles.

Enhancements

SC-4 (1) Security Levels

Withdrawn: Incorporated into SC-4.

SC-4 (2) Periods Processing

This control enhancement applies when there are explicit changes in information processing levels during information system operations, for example, during multilevel processing and periods processing with information at different classification levels or security categories. Organization-defined procedures may include, for example, approved sanitization processes for electronically stored information.

The information system prevents unauthorized information transfer via shared resources in accordance with Assignment: organization-defined procedures when system processing explicitly switches between different information classification levels or security categories.