NIST 800-53 REV 5 • SYSTEM AND COMMUNICATIONS PROTECTION
SC-34(1) — No Writable Storage
Employ {{ insert: param, sc-34.01_odp }} with no writeable storage that is persistent across component restart or power on/off.
Supplemental Guidance
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.
Practitioner Notes
Configure systems with no writable storage for the operating system and applications — all executable code comes from read-only sources.
Example 1: Deploy diskless workstations that PXE boot from a network server. The OS image is read-only on the server. Users save data to network shares, but the operating system itself cannot be permanently modified.
Example 2: Use immutable container images in Docker/Kubernetes. The container image is read-only at runtime. If an attacker modifies files inside the container, restarting it restores the original image. Persistent data is stored only in explicitly mounted volumes.