SC-34 Non-modifiable Executable Programs

Guidance: nonePolicy clause: noneWhat these mean

Baselines	Implementation level	Enhancements
Not in a baseline	System	2 (0 in a baseline)

Related controls: AC-3, SI-7, SI-14

Control statement

For [Assignment: organization-defined system components] , load and execute:

• a. The operating environment from hardware-enforced, read-only media; and
• b. The following applications from hardware-enforced, read-only media: [Assignment: organization-defined applications].

NIST discussion

The operating environment for a system contains the code that hosts applications, including operating systems, executives, or virtual machine monitors (i.e., hypervisors). It can also include certain applications that run directly on hardware platforms. Hardware-enforced, read-only media include Compact Disc-Recordable (CD-R) and Digital Versatile Disc-Recordable (DVD-R) disk drives as well as one-time, programmable, read-only memory. The use of non-modifiable storage ensures the integrity of software from the point of creation of the read-only image. The use of reprogrammable, read-only memory can be accepted as read-only media provided that integrity can be adequately protected from the point of initial writing to the insertion of the memory into the system, and there are reliable hardware protections against reprogramming the memory while installed in organizational systems.

Control enhancements

SC-34(1) No Writable Storage

Baselines: Not in a baseline

Employ [Assignment: organization-defined system components] with no writeable storage that is persistent across component restart or power on/off.

Discussion and assessment objectives for SC-34(1)

Disallowing writeable storage eliminates the possibility of malicious code insertion via persistent, writeable storage within the designated system components. The restriction applies to fixed and removable storage, with the latter being addressed either directly or as specific restrictions imposed through access controls for mobile devices.

Determine if [Assignment: organization-defined system components] are employed with no writeable storage that is persistent across component restart or power on/off.

Examine: System and communications protection policy; procedures addressing non-modifiable executable programs; system design documentation; system configuration settings and associated documentation; system architecture; list of system components to be employed without writeable storage capabilities; system audit records; system security plan; other relevant documents or records.

Interview: System/network administrators; organizational personnel with information security responsibilities; organizational personnel installing, configuring, and/or maintaining the system; system developers/integrators.

Test: Mechanisms supporting and/or implementing the employment of components with no writeable storage; mechanisms supporting and/or implementing persistent non-writeable storage across component restart and power on/off.

SC-34(2) Integrity Protection on Read-only Media

Baselines: Not in a baseline

Protect the integrity of information prior to storage on read-only media and control the media after such information has been recorded onto the media.

Discussion and assessment objectives for SC-34(2)

Controls prevent the substitution of media into systems or the reprogramming of programmable read-only media prior to installation into the systems. Integrity protection controls include a combination of prevention, detection, and response.

Determine if:

• SC-34(02)[01] the integrity of information is protected prior to storage on read-only media;
• SC-34(02)[02] the media is controlled after such information has been recorded onto the media;

Examine: System and communications protection policy; procedures addressing non-modifiable executable programs; system design documentation; system configuration settings and associated documentation; system architecture; system audit records; system security plan; other relevant documents or records.

Interview: System/network administrators; organizational personnel with information security responsibilities; organizational personnel installing, configuring, and/or maintaining the system; system developers/integrators.

Test: Mechanisms supporting and/or implementing the capability to protect information integrity on read-only media prior to storage and after information has been recorded onto the media.

Withdrawn enhancements: SC-34(3).

Assessment objectives (SP 800-53A)

Objectives and methods for SC-34

Determine if:

• SC-34a. the operating environment for [Assignment: organization-defined system components] is loaded and executed from hardware-enforced, read-only media;
• SC-34b. [Assignment: organization-defined applications] for [Assignment: organization-defined system components] are loaded and executed from hardware-enforced, read-only media.

Examine: System and communications protection policy; procedures addressing non-modifiable executable programs; system design documentation; system configuration settings and associated documentation; system architecture; list of operating system components to be loaded from hardware-enforced, read-only media; list of applications to be loaded from hardware-enforced, read-only media; media used to load and execute the system operating environment; media used to load and execute system applications; system audit records; system security plan; other relevant documents or records.

Interview: System/network administrators; organizational personnel with information security responsibilities; system developer; organizational personnel installing, configuring, and/or maintaining the system; system developers/integrators.

Test: Mechanisms supporting and/or implementing, loading, and executing the operating environment from hardware-enforced, read-only media; mechanisms supporting and/or implementing, loading, and executing applications from hardware-enforced, read-only media.