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Microsoft 365 Security: Why You’re Paying Twice Without Knowing

Written by Kathryn Reeves | Mar 11, 2026 3:47:56 PM

You Don’t Have a Security Gap. You Have a Visibility and Duplication Problem.  

For years, organisations have been told the same story: you need more security tools.
More vendors. More dashboards. More spend.

Yet in practice, most security leaders aren’t under protected, they’re over tooled and underinformed.

Here’s the uncomfortable truth many don’t want to admit: a significant proportion of security budgets are being wasted on tools that duplicate capabilities already owned inside Microsoft 365. Not because teams are careless, but because they lack visibility into what’s licensed, what’s enabled, and what’s actually being used.

This isn’t a security maturity problem.
It’s a value intelligence problem.

 

The Silent Drain on Security Budgets

Across UK organisations we work with, a recurring pattern emerges:

  • Microsoft 365 E5 is already in place
  • Multiple third-party security tools run alongside it
  • Core Microsoft security capabilities remain disabled, under configured, or misunderstood

The result?
Security teams pay two to three times for the same outcomes - endpoint protection, email security, identity controls, SIEM, DLP - without realising it.

Microsoft’s rapid pace of innovation has made it difficult for many organisations to adapt their operating models fast enough.

Security spend hasn’t grown smarter… it’s just grown noisier.


Why Duplication Happens (And Keeps Happening)

The problem isn’t that Microsoft security is “hidden”.
It’s that licensing complexity outpaced governance.

Microsoft 365 E5 alone spans more than 20 security and compliance capabilities across identity, endpoint, email, data, cloud apps, and SIEM/XDR. Defender, Entra ID, Purview, Sentinel, each powerful on its own, exponentially more effective when configured together.

Yet most organisations:

  • Don’t map third-party tools against E5 entitlements
  • Don’t know which E5 features are enabled vs licensed
  • Don’t track coverage across users, workloads, and risk areas

So they default to what feels safe: renewing contracts.

That’s how you end up paying for:

  • EDR twice
  • Email security twice
  • MFA and identity governance twice
  • DLP twice

And still feeling exposed.

 

The Myth: “More Tools = Better Security”

Here’s the controversial bit:
More tools often reduce security effectiveness.

Fragmented stacks mean:

  • Slower investigations
  • Missed correlations
  • More admin overhead
  • Higher operational risk

Microsoft’s security strategy is unapologetically about consolidation - a single, natively integrated control plane across identity, endpoint, data, and cloud.

That’s not a weakness.
It’s the Strategy.

When security telemetry lives inside the same ecosystem that generates the data, you get context, not just alerts.

The Counter Argument: “Best of Breed Still Wins”

Security purists will push back hard at this point… and not without reason.

The argument goes like this:
best of breed tools outperform platforms, and relying too heavily on a single vendor creates systemic risk. If Microsoft goes down, everything goes down. If an attacker bypasses one control, they bypass them all. Diversity, they argue, equals resilience.

On paper, that sounds sensible.

And in highly specialised environments - critical infrastructure, niche compliance regimes, advanced SOCs with deep inhouse capability - it can be true. Some organisations do need niche tooling that goes beyond what Microsoft offers today. Some third-party products are objectively stronger in very specific areas.

But here’s where the counterargument starts to fall apart in the real world.

 

Why “Best of Breed” Often Becomes “Worst of Both”

The issue isn’t the tools.
It’s the operating reality.

Most organisations don’t have:

  • The people to deeply configure every platform
  • The time to integrate signals properly
  • The budget to operationalise five or six security consoles at once

So “best of breed” quietly becomes:

  • Best of breed on day one
  • Average at best by month six
  • Shelfware by renewal time

Meanwhile, Microsoft security tools, already licensed, already integrated, already embedded into identity, data, and productivity, sit idle.

The result isn’t resilience.
It’s complexity debt.

 

Vendor Lock In vs Operational Lock Out

Another common objection is vendor lock in.

But most organisations aren’t locked into Microsoft, they’re already operationally dependent on it:

  • Identity runs through Entra ID
  • Collaboration lives in M365
  • Data resides in SharePoint, OneDrive, Exchange
  • AI is arriving via Copilot

Pretending security exists outside that reality doesn’t reduce risk, it disconnects security from where the risk actually lives.

The bigger danger today isn’t vendor concentration.
It’s security teams being locked out of clarity.

 

The Real Question No One Asks

The debate shouldn’t be platform vs best-of-breed.

It should be:

Are we getting full value and full protection from what we already own… before adding more?

If the answer is no, then adding another tool doesn’t make you safer.
It just makes the problem harder to see.

 

A More Honest Middle Ground

This isn’t an argument for ripping out everything non Microsoft.
It’s an argument for evidence led security decisions.

Use third-party tools where they genuinely add value.
But stop paying for duplication you can’t see, measure, or justify.

Because in most organisations, the biggest security risk isn’t a missing tool, it’s unused capability hiding in plain sight.

 

E5, E7, and the Shift to Security at Scale

Microsoft 365 E5 has long been positioned as the “premium” security SKU. Increasingly, that’s true, but the conversation is changing.

With Microsoft signalling the evolution towards frontier security and AI driven operations (now emerging through the E7 SKU), the message is clear:

Security at scale isn’t about buying more tools, it’s about operating what you already own, intelligently.

AI assisted investigation, unified XDR, identity first security, data protection for Copilot - these only work when:

  • Capabilities are enabled
  • Coverage is understood
  • Gaps are visible

Throwing another vendor into the mix doesn’t solve that.
Visibility does.

 

Activation Beats Procurement... Every Time

One of the most common discoveries during security rationalisation exercises is how much value is already sitting idle:

  • Attack Surface Reduction rules left in audit mode
  • Entra ID risk policies licensed but unused
  • Defender for Cloud Apps not connected to data sources
  • Purview DLP and sensitivity labels untouched

These aren’t “nice to haves”.
They’re frontline controls, already paid for.

The biggest security wins today don’t come from new contracts.
They come from turning things on properly.

 

This Is Where Most Organisations Get Stuck

Knowing this and proving it are two different things.

Security leaders don’t need another slide deck telling them E5 is powerful.
They need evidence:

  • What’s licensed vs enabled
  • Where duplication exists
  • Where risk and waste intersect
  • What to fix first

That’s where most strategies fail… not on vision, but on visibility.

The Role of Prism for Security

Prism for Security exists for one reason:
to make Microsoft security measurable, visible, and actionable.

It shows organisations:

  • What Microsoft security capabilities they own
  • What’s enabled, partially enabled, or unused
  • How coverage aligns to users and workloads
  • Where third-party tools overlap with Microsoft investment

Not as a theoretical exercise, but as a live, data driven view of your environment.

When you can see your security posture clearly, decisions change:

  • Renewals get questioned
  • Activation becomes the priority
  • Consolidation becomes realistic

Security becomes simpler… and stronger.

 

 The Bottom Line

If your organisation runs Microsoft 365 E5 (or is considering E7) and still feels the need to keep adding security tools, the issue isn’t capability.

It’s clarity.

Before you buy anything else, ask a harder question:

Do we actually know what we already have… and are we using it?

If the answer isn’t a confident yes, that’s your risk.

Prism for Security helps you uncover hidden risk, wasted spend, and untapped protection across your Microsoft environment, turning licensing complexity into security confidence.

If you want to stop guessing and start optimising, that’s where the conversation should begin.

 

If you'd like to learn more watch our Secure Smarter webinar On Demand