Block storage is a data storage model that organizes information into fixed-size blocks, commonly used for cloud volumes and virtual disks. Security teams need visibility into it because sensitive data frequently resides there even when attention is focused on object storage.
Block Storage as a Storage Primitive
Block storage presents data as addressable fixed-size blocks, which makes it behave more like a raw disk than a file share or object repository. That model is why it underpins virtual machines, database volumes, and other workloads that expect low-level, predictable read and write operations.
For security teams, the practical point is that block storage is often invisible at the application layer while still holding highly sensitive data. A volume can be detached, copied, snapshotted, or reattached long before anyone notices the data it contains, so governance needs to follow the volume itself, not just the workload using it.
Where Block Storage Fits in Cloud and Virtualized Systems
Block storage is commonly used for cloud disks, SAN-backed volumes, and persistent storage attached to servers, containers, or virtual machines. Because it is usually mounted into an operating system, the security boundary is often the host, hypervisor, or cloud control plane rather than the storage medium alone.
This matters when teams compare storage models. Object storage is better suited to unstructured content and API-driven access, while block storage is usually chosen for performance, compatibility, and application state. The choice affects how data is discovered, protected, backed up, and recovered.
Cloud platforms also expose block storage through management APIs and orchestration layers, which means access controls around volume creation, attachment, snapshotting, and deletion are part of the security model. If those controls are weak, the storage service can become a path to data exposure even when the underlying disk technology is sound.
Security Characteristics of Block Storage
Block storage security is shaped by who can provision volumes, who can attach them, how encryption is enforced, and how snapshots and replicas are handled. A well-managed block volume can be strongly protected, but it can also inherit risk from permissive infrastructure access and from the system that mounts it.
Because data is stored at the block level, confidentiality depends heavily on encryption, access separation, and the controls around keys and credentials used to manage the storage service. Integrity also matters, since unauthorized writes at the volume level can alter application state, logs, databases, or system images.
Visibility is another defining characteristic. Security tools may see the host or workload, but not the full contents of the volume unless the environment is instrumented for storage discovery and classification. For that reason, block storage often requires explicit inventory and data handling policies rather than assuming the attached application will reveal what is inside.
How Block Storage Differs from Other Storage Models
Compared with file storage, block storage gives the operating system more control over how data is structured and accessed. Compared with object storage, it usually delivers lower latency and higher predictability, but it also shifts more responsibility to the host operating system, filesystem, and application stack.
That difference changes the operational security posture. In block storage, the volume may be only one layer in a chain that includes the VM, the hypervisor, the cloud account, the backup system, and the snapshot catalogue. A weakness at any of those layers can expose data even if the block device itself is encrypted and functioning correctly.
This is why many environments treat block storage as a workload dependency that must be governed alongside compute. The storage layer may not be the visible target, but it is often where sensitive application data, database pages, and operating system artifacts are actually kept.
Risk and Threat Considerations
Block storage can become a quiet exposure point because the volume itself is often not the thing users monitor most closely. Unauthorized attachment, snapshot abuse, over-permissive management access, or failure to encrypt at rest can all turn a routine storage asset into a direct data exposure path.
Failure mechanism: An attacker or insider with control-plane or host-level access can copy, attach, or mount a volume, then read sensitive data without needing to compromise the application that uses it. Mismanaged snapshots and backups can create the same outcome if they are left broadly accessible or poorly governed.
Impact: The result can be disclosure of databases, configuration secrets, customer records, and system images, plus integrity loss if the attacker can write to the volume. In large cloud environments, the damage can scale quickly because storage assets are easy to clone and difficult to notice once detached from their original workload.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 sets the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | SC-28 — Protection of Information at Rest | Block storage commonly holds sensitive data at rest on cloud volumes and disks. |
| AC-6 — Least Privilege | Volume attach, snapshot, and restore permissions directly affect who can reach stored data. | |
| CM-8 — System Component Inventory | Block volumes and snapshots must be discoverable to govern where data resides. | |
| Recommendation — Encrypt block volumes at rest and verify the storage layer enforces the required protection. Restrict volume and snapshot administration to the minimum required set of principals. Inventory volumes, snapshots, and replicas so hidden data stores do not escape governance. | ||
| ISO/IEC 27001:2022 | A.8.24 — Use of cryptography | Block storage often relies on encryption to protect data stored on volumes and snapshots. |
| Recommendation — Apply cryptography controls to block volumes and their backups where data confidentiality requires it. | ||
Practitioner Guidance
Why practitioners should care: Block storage is not just capacity for virtual disks, it is a control surface for sensitive workload data. Ownership should therefore include encryption, volume lifecycle, snapshot governance, and visibility into which systems actually depend on each volume.
What to watch for: Review who can create, attach, snapshot, restore, and delete volumes, and treat those permissions as data-access permissions in practice. Also watch for stale volumes, orphaned snapshots, and copied disks that outlive the systems they were meant to support.
Practitioner takeaway: If the volume can be cloned, mounted, or restored, it needs the same level of security attention as the workload that uses it.
Related resources from NHI Mgmt Group
- What is the difference between scanning block storage and scanning object storage for data risk?
- What is the difference between secret storage and secret governance for agents?
- When should organisations block anonymous network traffic at login?
- When should organisations block an AI service rather than permit it?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 28, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
