Replacing a Fragmented Security Stack Without Leaving Gaps

Most security stacks aren’t designed. They build up over time.

An endpoint product chosen years ago. A separate email filter. A firewall from another vendor. Microsoft 365 security features that are licensed but only partly switched on. Each one was a perfectly reasonable decision at the time. Put together, though, they leave your team juggling multiple consoles and inconsistent alerts with no single view of what’s happening.

Consolidating onto one integrated, monitored platform is often the right answer. The catch is that the migration itself carries risk. Rush it, and you can leave devices unprotected, break business applications or overwhelm the internal team.

Here are the nine steps we follow to make sure that doesn’t happen:

1. Start with an honest inventory

You can’t protect what you can’t see. Before deploying anything, compare every source of truth: your device management platform, the existing security console, the asset register and your team’s own records. They rarely agree. Devices that haven’t checked in for months, duplicate records and forgotten servers all tend to surface here. Finding them now prevents the classic mistake of discovering an unprotected laptop after the old product has gone.

2. Agree the plan before touching anything

A security migration touches every device and identity in the business, so governance matters. Agree what’s in and out of scope, who approves each stage, the acceptance criteria for the pilot and each wave, escalation contacts on both sides, and how users and the service desk will be kept informed. When we replaced Newmarket Holidays’ security stack, all of this went into a signed project initiation document before a single change was made.

3. Review your wider baseline at the same time

A migration is a good moment to check where the rest of your controls stand. Running a Microsoft 365 security baseline review alongside the project gives everyone an evidence-based view of identity, device, email and data security, and turns a one-off swap into the first step of a proper improvement roadmap.

4. Deploy through your management platform

Where you can, push the new agents out through your existing device management tool, such as Microsoft Intune, rather than installing them by hand. It’s quicker, repeatable and auditable, and it makes it easy to see exactly which devices have the new protection and which don’t.

5. Run a proper pilot

Choose a pilot group that reflects the real estate: different device types, departments and critical applications. Use it to test compatibility with line-of-business software, device performance, alerting and escalation, and how the old and new products behave running side by side. Don’t move on until the pilot has been formally signed off.

6. Roll out in waves

Deploy to the rest of the business in planned waves rather than all at once. After each wave, check coverage, look into any failures and keep an exception list for devices that were offline or need extra work. It keeps problems small and easy to deal with.

7. Remove the old product last

If there’s one rule to remember, it’s this. Only remove the previous security product once the new protection is confirmed as installed, healthy and reporting on each device. Never the other way round. Stick to that, and the business is never left exposed during the changeover.

8. Connect identities and the network, not just endpoints

Modern attacks rarely stay on one device. Bringing Microsoft 365 identity monitoring and firewall logs into the same platform means analysts can join the dots: a suspicious sign-in, followed by unusual mailbox activity, followed by an odd outbound connection from a laptop.

9. Hand over to 24/7 monitoring

Once everything’s deployed, the platform should be watched around the clock by a security operations centre that triages alerts and only escalates what matters. Agree in advance which actions can be taken automatically, and which need your team’s approval.

The value often shows up quickly. At Newmarket Holidays, the SOC flagged a potentially risky third-party app with access to their Microsoft 365 environment within days of going live, along with clear steps to fix it. The full project is covered in our Newmarket Holidays case study.

Warning signs your migration is at risk

It’s worth pausing if device counts don’t match between systems; if nobody has agreed what “done” looks like for each wave; if the pilot group is just the IT team, or if there’s pressure to remove the old product early because the renewal date is looming. Those are exactly the moments when gaps appear.

Planning a security consolidation?

Here at Reliable, we work alongside internal IT and security teams to replace fragmented tools with integrated, 24/7 managed protection, planned and delivered as one team.

If you’re weighing up a change, our complimentary Security & Resilience Review is a sensible starting point. We’ll look at your current setup and priorities, and give you a short summary of the areas worth investigating before you commit to anything. It’s an introductory review, not a full technical audit.

Fewer consoles, less noise and no gaps. That’s what a good consolidation should leave behind.