5 Best Ransomware-Proof Enterprise Backup Solutions 2026

Intro

Ransomware has evolved from a data encryption problem into a backup destruction problem. According to the Sophos State of Ransomware 2025 report, 96% of ransomware attacks now specifically target backup repositories — and 76% succeed in compromising them. The strategy is straightforward: if attackers can destroy or encrypt your backups before triggering the payload, recovery becomes impossible or prohibitively expensive.

This shifts the question from "do we have backups?" to "are our backups actually ransomware-proof?" A backup that can be deleted by anyone with admin credentials is not ransomware-proof. A backup that depends on a software policy to enforce retention is not ransomware-proof. Genuine ransomware resilience requires that the backup storage layer enforces immutability independently — meaning the storage itself refuses deletion requests, regardless of who sends them.

The five solutions below represent the most credible approaches to this problem in the enterprise market. Each one provides meaningful protection against backup-targeting ransomware, though they differ significantly in how that protection is implemented and what trade-offs come with it.

1. Object First Ootbi

Object First Ootbi is built around a concept called Absolute Immutability — a term that distinguishes what Ootbi does from standard immutable backup storage and is worth understanding precisely, because the difference determines how the solution holds up when an attacker has already compromised administrative credentials.

What Absolute Immutability means

Most backup storage platforms offer immutability at the policy layer: a retention setting instructs the system not to delete objects before a certain date. This works against unsophisticated attacks. But it has a fundamental weakness — the policy lives in software, and software can be reconfigured by anyone with sufficient privileges. A ransomware operator who compromises storage admin credentials can, on most platforms, simply change the retention policy and then delete the backups.

Absolute Immutability closes this gap through three independent enforcement layers that operate simultaneously. The first is S3 Object Lock in compliance mode at the protocol level — the industry-standard WORM mechanism that prevents object deletion or modification during the retention window. The second is an OS-level root access block: Ootbi's operating system has no accessible root shell, which means there is no software path to override the retention policy even with administrative credentials. The third is hardware-locked firmware: the firmware itself is signed and sealed, blocking any modification that could introduce a bypass mechanism. These three layers are independent — compromising one does not compromise the others. Absolute Immutability means that no software action, regardless of the credentials behind it, can delete backup data within its retention window. The only way to destroy an Ootbi backup is to physically destroy the hardware.

Ootbi is the only purpose-built immutable backup appliance designed for Veeam environments. It ships as a 2U appliance (18TB per node, clusterable to 1.7PB), carries the full Veeam Ready certification stack (Object, Repository, SOSAPI, IAM STS), and holds ZTDR (Zero Trust Data Resilience) certification — confirming physical and logical separation between the backup application tier and the storage tier. Setup takes approximately 15 minutes.

At the 2026 Storage Awards, Ootbi won both "Enterprise Backup Hardware Vendor of the Year" and "Ransomware Company of the Year" — the latter decided by public vote from the UK tech community. "Ransomware threats continue to evolve, and organizations are increasingly prioritizing our secure, absolutely immutable backup storage as a necessary component of their cyber resilience strategy," said Daniel Fried, SVP Worldwide Sales at Object First.

Why it's ransomware-resistant

• Absolute Immutability: three independent enforcement layers (S3 Object Lock compliance, OS root block, hardware-locked firmware)

• No software-accessible override path — admin credential compromise does not enable backup deletion

• Full Veeam Ready certification stack + ZTDR certified

Best for: Veeam environments requiring the highest level of hardware-enforced ransomware protection

2. ExaGrid

ExaGrid protects backup data through a tiered architecture with a network-isolated immutability zone. Incoming backup data lands in a performance-optimized Landing Zone for fast restores. After a configurable delay, data moves to the Retention Time-Lock tier — a network-isolated zone that becomes read-only and unreachable from the network for the duration of the retention window.

The ransomware-protection value is in the network isolation: even if an attacker fully compromises the backup application server and the storage admin account, the Retention Time-Lock tier is not accessible from the network during the lock period. Ransomware that targets backup deletion by authenticating to the storage system simply cannot reach the locked tier.

ExaGrid works with all major backup platforms — Veeam, Commvault, Veritas NetBackup, Dell EMC NetWorker — making it a strong choice for enterprises running mixed backup environments. The built-in deduplication engine meaningfully reduces the storage footprint for long-retention policies.

Why it's ransomware-resistant

• Network-isolated Retention Time-Lock tier — unreachable from network during retention window

• Application-agnostic: Veeam, Commvault, Veritas, NetWorker all supported

• Built-in deduplication reduces long-term storage footprint

Best for: Multi-application enterprise environments that need network-isolated immutable backup with deduplication

3. Cloudian HyperStore

Cloudian HyperStore is an enterprise S3-compatible object storage platform that implements S3 Object Lock in both compliance and governance modes. In compliance mode, retention locks cannot be shortened or removed by any user — including the storage administrator — which eliminates the risk of a ransomware operator using compromised admin credentials to delete backup objects.

HyperStore is designed for petabyte-scale deployments and has a well-established compliance track record: it is recognized in guidance for SEC 17a-4(f) WORM storage, making it particularly relevant for financial services and healthcare enterprises where regulatory data retention requirements overlap with ransomware protection needs. Multi-tenancy and QoS controls allow large organizations to manage backup storage for multiple business units from a single platform.

Deployment is software-defined on Cloudian-certified hardware or existing servers. HyperStore supports erasure coding and multi-site replication with consistent Object Lock semantics across sites.

Why it's ransomware-resistant

• S3 Object Lock compliance mode: admin credentials cannot override retention

• Regulatory pedigree: recognized in SEC 17a-4(f) WORM guidance

• Petabyte-scale with multi-tenancy, QoS, and multi-site replication

Best for: Large enterprises and regulated industries that need petabyte-scale immutable object storage with compliance credentials

4. StoneFly

StoneFly offers purpose-built ransomware-proof backup storage through a combination of immutable snapshots, air-gapping capability, and multi-layer access controls. Their backup appliances — including the DR365V series — are designed to provide an isolated, hardened target for enterprise backup data with built-in defenses against ransomware-driven backup deletion.

The core protection mechanism is immutable snapshots with configurable lock periods: once a snapshot is taken and locked, it cannot be deleted or modified until the retention period expires, regardless of administrator credentials. StoneFly layers this with optional air-gap configurations that physically isolate the backup repository from the network after each backup job completes — eliminating network-based attack vectors entirely.

StoneFly appliances support both on-premises deployment and hybrid configurations that include cloud-connected vaulting to AWS, Azure, or Google Cloud. Integration with Veeam, Commvault, and Veritas allows enterprises to use StoneFly as a hardened secondary backup target within existing workflows.

Why it's ransomware-resistant

• Immutable snapshots with configurable lock periods

• Optional air-gap mode that physically isolates the repository after each backup job

• Hybrid support: on-prem appliance with cloud-connected vaulting to AWS, Azure, or GCP

Best for: Enterprises that want air-gap capability combined with immutable snapshots and cloud vaulting flexibility

5. Pure Storage SafeMode Snapshots

Pure Storage SafeMode addresses ransomware protection for organizations already running Pure FlashArray or FlashBlade as primary storage. It makes volume snapshots eradication-proof by requiring vendor authorization before any SafeMode-protected snapshot can be permanently deleted — introducing a mandatory delay and out-of-band human verification that breaks automated ransomware playbooks.

The mechanism is architecturally different from S3 Object Lock or network isolation. SafeMode does not rely on a protocol-level retention policy that an attacker might find a way to modify. Instead, deletion requires contacting Pure Storage support, who verify the request through a separate authentication channel before enabling eradication. An attacker with full admin credentials to the storage array still cannot delete SafeMode snapshots without Pure's involvement — which is the key ransomware protection property.

SafeMode is best understood as a snapshot ransomware protection layer for Pure-native environments, not a standalone backup repository. Organizations running Pure primary storage get meaningful ransomware protection without deploying additional hardware or a separate backup target.

Why it's ransomware-resistant

• Vendor-authorized eradication — snapshot deletion requires out-of-band Pure Storage approval

• Protects FlashArray and FlashBlade with no additional hardware required

• Breaks automated ransomware deletion sequences through mandatory human verification

Best for: Pure Storage environments that need ransomware-proof snapshot protection without additional backup hardware

What makes backup storage actually ransomware-proof?

The term "ransomware-proof" is used loosely in vendor marketing. There are three concrete criteria that separate genuinely ransomware-resistant backup storage from platforms that are merely hardened against unsophisticated attacks.

1. Can the retention policy be modified with admin credentials?

If an admin with full storage credentials can shorten or remove a retention lock, then ransomware that compromises those credentials can delete backups. Compliance-mode S3 Object Lock and hardware-level controls address this; governance-mode policies and software-only retention settings do not.

2. Is the backup storage reachable from the backup application server?

ZTDR and similar frameworks require separation between the backup application tier and the storage tier. If an attacker compromises the backup server, they should not be able to use credentials from that server to access the backup storage directly. Network isolation and management plane separation both address this.

3. Is there a software-accessible override mechanism?

Some platforms include "break glass" mechanisms — administrative overrides that exist for legitimate recovery scenarios. These are ransomware attack surfaces. The strongest ransomware-proof storage platforms either eliminate these overrides entirely (as Ootbi does with hardware-locked firmware and no root shell) or move the override out of band entirely (as Pure Storage SafeMode does with vendor-authorized eradication).

Choosing the right solution

For Veeam-centric environments that need the strongest possible hardware-enforced protection, Ootbi's Absolute Immutability — three independent enforcement layers with no software override path — sets the benchmark in this category. ExaGrid is the right choice for multi-application enterprises that need network-isolated immutability with deduplication savings. Cloudian HyperStore fits large-scale environments in regulated industries where compliance track record matters alongside petabyte-scale capacity. StoneFly offers the most flexibility for organizations that need configurable air-gap capability combined with cloud vaulting. Pure Storage SafeMode is the practical answer for enterprises already running Pure primary storage that want meaningful ransomware protection without additional hardware investment.

The underlying requirement is consistent: ransomware-proof backup storage must enforce immutability at a layer that an attacker cannot reach with compromised credentials. The question to ask every vendor is simple — if I give you admin credentials right now, what prevents me from deleting a backup that was created an hour ago?