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Written by: Jaysn Rye

As adversaries grow faster, stealthier, and more destructive, traditional recovery strategies are increasingly insufficient. Mandiant's M-Trends 2025 report reinforces this shift, highlighting that ransomware operators now routinely target not just production systems but also backups. This evolution demands that organizations re-evaluate their resilience posture. One approach gaining traction is the implementation of an isolated recovery environment (IRE)—a secure, logically separated environment built to enable reliable recovery even when an organization's primary network has been compromised.

This blog post outlines why IREs matter, how they differ from conventional disaster recovery strategies, and what practical steps enterprises can take to implement them effectively.

Most organizations assume that regular backups equal resilience; however, that assumption doesn't hold up against today's threat landscape. Ransomware actors and state-sponsored adversaries are increasingly targeting backup infrastructure directly, encrypting, deleting, or corrupting it to prevent recovery and increase leverage.

The M-Trends 2025 report reveals that in nearly half of ransomware intrusions, adversaries used legitimate remote management tools to disable security controls and gain persistence. In these scenarios, the compromise often extends to backup systems, especially those accessible from the main domain.

Figure 1: Observed tools in 2024 ransomware-related investigations (source: M-Trends 2025)

In short: your backup isn't safe if it's reachable from your production network. During an active incident, that makes it irrelevant.

An isolated recovery environment (IRE) is a secure enclave designed to store immutable copies of backups and provide a secure space to validate restored workloads and rebuild in parallel while incident responders carry out the forensic investigation. Unlike traditional disaster recovery solutions, which often rely on replication between live environments, an IRE is logically and physically separated from production.

At its core, an IRE is about assuming a breach has occurred and planning for the moment when your primary environment is lost, ensuring you have a clean fallback that hasn't been touched by the adversary.

• Separation of infrastructure and access: The IRE must be isolated from the corporate environment. No shared authentication, no shared tooling, no shared infrastructure or services, no persistent network links or direct TCP/IP connections between the production environment and the IRE.
• Restricted administrative workflows: Day-to-day access is disallowed. Only break-glass, documented processes exist for access during validation or recovery.
• Known-good, validated artifacts: Data entering the IRE must be scanned, verified, and stored with cryptographic integrity checks all while maintaining the isolation controls.
• Validation environment and tools: The IRE must also include a secured network environment, which can be used by security teams to validate restored workloads and remove any identified attacker remnants.
• Recovery-ready templates: Rather than restoring single machines, the IRE should support the rapid rebuild of critical systems in isolation with predefined procedures.

Successfully implementing an IRE is not a checkbox exercise. It requires coordination between security, infrastructure, identity management, and business continuity teams. The following breaks down the major building blocks and considerations.

The foundational principle behind an IRE is separation. The environment must not share any critical infrastructure, identity, network, hypervisors, storage, or other services with the production environment. In most cases, this means:

• Dedicated platforms (on-premises or cloud based) and tightly controlled virtualization platforms

• No routable paths from production to the IRE network

• Physical air-gaps or highly restricted one-way replication mechanisms

• Independent DNS, DHCP, and identity services

Figure 2 illustrates the permitted flows into and within the IRE.

Figure 2: Typical IRE architecture

Identity is the primary attack vector in many intrusions. An IRE must establish its own identity plane:

• No trust relationships to production Active Directory

• No shared local or domain accounts

• All administrative access must require phishing resistant multi-factor authentication (MFA)

• All administrative access should be via hardened Privileged Access Workstations (PAW) from within the IRE

• Where possible, implement just-in-time (JIT) access with full audit logging

Accounts used to manage the IRE should not have any ties to the production environment; this includes being used from a device belonging to the production domain. These accounts must be used from a dedicated PAW.

Administrative access is often the weak link that attackers exploit. That's why an IRE must be designed with tight control over how it's managed, especially during a crisis.

In the following model, all administrative access is performed from a dedicated PAW. This workstation sits inside an isolated management zone and is the only system permitted to access the IRE's core components.

Here's how it works:

• No production systems, including IT admin workstations, are allowed to directly reach the IRE. These paths are completely blocked.

• The PAW manages the IRE's:

• Isolated Data Vault, where validated backups are stored.

• Management Plane, which includes IRE services such as Active Directory, DNS, PAM, backup, and recovery systems.

• Green VLAN, which hosts rebuilt Tier-0 and Tier-1 infrastructure.

• Any restored services go first into a yellow staging VLAN, a controlled quarantine zone with no east-west traffic. Systems must be verified clean before moving into the production-ready green VLAN. Remote access to machines in the yellow VLAN is restricted to console only access (hypervisor or iLO consoles) from the PAW. No direct RDP/SSH is permitted.

This design ensures that even during a compromise of the production environment, attackers can't pivot into the recovery environment. All privileged actions are audited, isolated, and console-restricted, giving defenders a clean space to rebuild from.

Figure 3: Permitted administration paths

How data enters the IRE is just as important as how it's managed. Backups that are copied into the data transfer zone must be treated as potentially hostile until proven otherwise.

To mitigate risk:

• Data must flow in only one direction, from production to IRE, never the other way around.*

• This is typically achieved using data diodes or time-gated software replication that enforces unidirectional movement and session expiry.

• Ingested data lands in a staging zone where it undergoes:

• Hash verification against expected values.

• Malware scanning, using both signature and behavioural analysis.

• Cross-checks against known-good backup baselines (e.g., file structure, size, time delta).

Once validated, data is committed to immutable storage, often in the form of Write Once, Read Many (WORM) volumes or cloud object storage with compliance-mode object locking. Keys for encryption and retention are not shared with production and must be managed via an isolated KMS or HSM.

The goal is to ensure that even if an attacker compromises your primary backup system, they cannot alter or delete what's been stored in the IRE.

*Depending on overall recovery strategies, it's possible that restored workloads may need to move from the IRE back to a rebuilt production environment. 

An IRE is only useful if it enables recovery under pressure. That means planning and testing full restoration of core services. Effective IRE implementations include:

• Templates for rebuilding domain controllers, authentication services, and core applications

• Automated provisioning of VMs or containers within the IRE

• Access to disaster recovery runbooks that can be followed by incident responders

• Scheduled tabletop and full-scale recovery exercises (e.g., quarterly or bi-annually)

Many organizations discover during their first exercise that their documentation is out of date or their backups are incomplete. Recovery drills allow these issues to surface before a real incident forces them into view.

If you're relying on the IRE for forensic investigation as well as recovery, it's essential to ensure the integrity of system logs and metadata. This is where hash chaining becomes important.

• Implement hash chaining on logs stored in the IRE to detect tampering.

• Apply digital signatures from trusted, offline keys.

• Regularly verify the chain against trusted checkpoints.

This ensures that during an incident, you can prove not only what happened but also that your evidence hasn't been modified, either by an attacker or by accident.

The right model depends on your environment, compliance obligations, and team maturity.

Model

Advantages

Challenges

On-Premises

Full control, better for air-gapped environments

Higher CapEx, longer provisioning time, less flexibility

Cloud

Faster provisioning, built-in automation, easier to test

Requires strong cloud security maturity and IAM separation

Hybrid

Local speed + cloud resilience; ideal for large orgs with critical workloads

More complex design; requires secure identity split and replication paths

• Over-engineering for normal operations: The IRE is not a sandbox. Avoid mission creep.

• Using the IRE beyond cyber recovery: The IRE is not for DR testing, HA, or daily operations. Any non-incident use risks breaking its isolation and trust model.

• Assuming cloud equals isolation: Isolation requires deliberate configuration. Cloud tenancy is not enough.

• Neglecting insider threats: The IRE must defend against sabotage from inside the organization, not just ransomware.

As attackers accelerate and the blast radius of intrusions expands, the need for trusted, tamper-proof recovery options becomes clear. An isolated recovery environment is not just a backup strategy, it is a resilience strategy.

It assumes breach. It accepts that visibility may be lost during a crisis. And it gives defenders a place to regroup, investigate, and rebuild.

The Mandiant M-Trends 2025 report makes it clear; the cost of ransomware isn't just in ransom paid, but in days or weeks of downtime, regulatory penalties, and reputation loss. The cost of building an IRE is less than a breach, and the peace of mind it offers is far greater.

For deeper technical guidance on building secure recovery workflows or assessing your current recovery posture, Mandiant Consulting offers strategic workshops and assessment services.

A special thanks to Glenn Staniforth for their contributions.

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