When leadership asks us "which endpoint security product should we choose," the honest answer is usually that the question is no longer the right one to ask first. A decade ago, when an attack began with a malicious executable opened on a workstation, the EDR was the chokepoint. Catch the executable, catch the attack. Best-of-breed EDR products competed on detection accuracy at that single point of contact, and the best ones genuinely did win.
That world has moved. The attacks we have responded to most often in the last twelve months did not start on the endpoint. They started with a phishing email that stole a session token. Or a malicious OAuth consent grant against a Microsoft 365 application. Or an attacker buying credentials on a marketplace and signing in legitimately from a residential proxy. By the time those attacks touched an endpoint, if they touched one at all, the EDR's role had narrowed to "one signal among many," and the EDR alone could not see what had happened upstream.
This post is about the architectural shift that change represents, and why for Microsoft 365 environments specifically, the conversation has moved from "which EDR" to "which ecosystem can correlate what is happening across email, identity, endpoints, cloud apps, and data simultaneously."
What still matters in EDR
Before going further: best-of-breed EDR products are still genuinely good at what they do. CrowdStrike Falcon, SentinelOne, and similar standalone EDR platforms have invested heavily in kernel-level visibility, fileless attack detection, behavioral analytics, and managed threat hunting. For organizations whose threat model is dominated by endpoint-originated attacks (advanced persistent threats targeting specific machines, sophisticated malware delivery, supply chain compromise via signed binaries), the depth of a dedicated EDR remains meaningful.
The case we are making is not that those products are bad. It is that for the SMB and mid-market organizations operating in Microsoft 365, the dominant attack patterns do not start on the endpoint, and the EDR-only approach optimizes for a chokepoint that attackers have largely moved past.
How modern attacks actually unfold
The attack chains we see most often in 2025-2026 look something like this:
Step 1: Initial access via identity or email. An adversary-in-the-middle phishing kit (Tycoon, Evilginx, Mamba 2FA) captures a session token from an employee who enters credentials and MFA approval into what appears to be a legitimate Microsoft sign-in page. The token bypasses MFA entirely because the attacker is replaying a valid authenticated session. We covered this attack pattern in detail in our post on token theft and why MFA alone is not enough.
Step 2: Reconnaissance via cloud applications. With a valid session, the attacker reads the user's mailbox, browses their SharePoint and OneDrive content, queries Microsoft 365 Copilot if it is enabled (we wrote about this risk in Copilot governance), and identifies which mailboxes belong to executives or finance staff. No malware. No endpoint involvement.
Step 3: Lateral movement via OAuth grants or delegation. The attacker creates an OAuth application consent that grants them persistent access to the mailbox even if the user later changes their password. Or they configure mailbox forwarding rules that exfiltrate every incoming message. Or they delegate permissions to other accounts. Still no endpoint involvement.
Step 4: Monetization. Wire fraud via business email compromise, payroll diversion, vendor invoice manipulation, or ransomware initiation through the now-compromised cloud presence. Only at this last step, in some attacks, does the endpoint become a factor.
A standalone EDR sees little to none of steps 1 through 3. The endpoint may receive its first signal only at step 4, after the damage is largely done. The EDR is not failing at its job; the attack simply did not pass through the EDR's field of view until the very end.
What "ecosystem" actually means in Microsoft Defender
Microsoft's security architecture is not one product called Defender. It is a set of products that share telemetry and correlation under the Microsoft Defender XDR umbrella. For an attack like the one above, the products that matter are:
Defender for Office 365 sees the phishing email at delivery, can rewrite the malicious link, detonates attachments, and flags impersonation attempts. If the email gets through delivery filters, post-delivery scanning can still pull it from inboxes after the fact.
Defender for Identity monitors Active Directory and Entra ID for unusual sign-in patterns, suspicious authentication behavior, and lateral movement patterns including the token theft scenarios that bypass MFA. It produces alerts that correlate with sign-in events Microsoft Entra Identity Protection is already scoring for risk.
Defender for Cloud Apps monitors session activity inside the cloud apps themselves. Mass downloads, atypical access patterns, OAuth consent grants from unusual sources, and the kind of reconnaissance behavior described in step 2 above are visible here in ways they are not visible to any endpoint product.
Defender for Endpoint (or Defender for Business in SMB tenants) sees what happens on the endpoint itself: process behavior, file operations, network connections, exploit attempts. For attacks that do reach the endpoint, this is where the EDR work happens.
Microsoft Intune is not a Defender product technically, but it is the device management layer that makes Conditional Access policies enforceable. Without Intune (or equivalent), a "require compliant device" policy has nothing to evaluate against. We covered this in our post on Conditional Access mistakes.
Microsoft Purview monitors the data layer: DLP policies that catch sensitive content moving to unauthorized destinations, insider risk signals, and audit trails across the entire estate.
The architectural argument is that these products are not five separate tools competing for budget. They are five surfaces of the same attack chain, and they share telemetry through Microsoft Defender XDR's correlation engine. An alert from Defender for Identity (unusual sign-in) can automatically trigger isolation of the affected user's endpoint via Defender for Endpoint, revocation of active sessions via Entra ID, and audit log capture via Purview, all without manual coordination.
This is called Automatic Attack Disruption when the correlation results in containment action. We covered it in our post on the newest Microsoft 365 security features. It is one of the most under-deployed capabilities in Microsoft 365 tenants we audit, and it is the closest thing to a "the whole stack acts together" feature in any vendor's portfolio.
What a standalone EDR cannot replicate
When organizations deploy a best-of-breed EDR alongside Microsoft 365 but skip the rest of the Defender stack, the standalone product typically integrates with Microsoft 365 via API connectors, syslog forwarding, or a SIEM in the middle. This integration works for some scenarios and is genuinely useful for many. It also has structural limits:
Latency. Native correlation inside Defender XDR happens at machine speed. Cross-vendor correlation goes through API rate limits, SIEM normalization pipelines, and analyst review queues. Attacks that complete in 30-60 minutes (token theft to BEC fraud is often this fast) outrun the integration.
Identity layer visibility. Most standalone EDR products have limited or no visibility into the identity layer itself. They see endpoint-side outcomes of identity-layer events, not the events themselves. Defender for Identity reads the AD and Entra ID signals natively, in real time, with risk scoring already applied.
Cloud app session visibility. This one is the largest single gap. Standalone EDR products do not see what happens inside SharePoint, Exchange, Teams, or third-party SaaS apps. Defender for Cloud Apps does. For attacks that live entirely within the cloud presence, this matters.
Automated response across domains. A standalone EDR can isolate an endpoint when it detects a compromise. It generally cannot revoke that user's active sessions across Microsoft 365, force a password change, expire OAuth grants, and quarantine related emails. Defender XDR's Automatic Attack Disruption does all of this from a single correlated detection.
When a hybrid approach makes sense
This is not a "all-Microsoft or nothing" argument. We have clients who run Microsoft Defender for everything except endpoint, where they use a best-of-breed EDR for specific reasons: existing investment, specialized industry requirements, threat hunting maturity that benefits from the vendor's managed services, or simply organizational preference. That architecture can work, and it can work well, provided the integration is configured properly and the operational team understands what each tool sees and does not see.
What we counsel against is the inverse: running a best-of-breed EDR and leaving Microsoft 365 protected only by Defender for Office 365 default policies and whatever Conditional Access exists. The endpoint gets premium coverage and the rest of the attack surface gets minimal coverage. The attacks targeting the rest of the attack surface, which is most of them now, are exactly what the standalone EDR cannot see.
What we recommend for SMBs and mid-market
For most Microsoft 365 SMBs and mid-market organizations we work with, the path that delivers the best security outcome per dollar spent is:
- Activate the Defender products already included in the license. Business Premium tenants have Defender for Office 365 Plan 1 and Defender for Business. E3 tenants have Defender for Office 365 Plan 1. E5 tenants have the full suite. Most of this capability ships turned off or under-configured. We discussed this gap extensively in our post on what we found auditing Microsoft 365 tenants.
- Add Intune device management so that compliance state can be checked and enforced via Conditional Access. The capability is in Business Premium and above; the configuration work is where most tenants fall short.
- Add Defender for Cloud Apps standalone if not on E5. This is the single most consistently undervalued add-on for SMBs running outside of E5 licensing. The shadow IT visibility, session policies, and AI security dashboard it provides cover gaps that no other tool in the stack covers.
- Reserve standalone best-of-breed EDR for cases where the threat model genuinely justifies it. Specific industries (defense contractors, financial services with elevated threat profile, organizations with active APT exposure) may have requirements that warrant the additional layer. Most SMBs do not.
How NeoDefender helps
Our work with cybersecurity managed services is built around the ecosystem approach described above. We are a Microsoft Solutions Partner because we believe the integrated stack delivers better outcomes for the organizations we work with than swapping individual products in and out. That is not a vendor loyalty argument. It is a coverage and correlation argument we have tested against real incidents.
If your organization is currently running a best-of-breed EDR alongside Microsoft 365 with limited integration, or running Microsoft 365 without the Defender products you have already paid for, the Reality Check is where we benchmark what you have, what you are missing, and where the highest-leverage gaps are.
Schedule a call with the NeoDefender team to talk through how the Defender ecosystem could be configured in your specific environment, and where the trade-offs with your current stack actually land.
