Connected Apps Are the New Attack Surface in Microsoft 365 (And It’s Not Mainstream Yet)
- AppGuard360 Research Team
- 26 minutes ago
- 4 min read
Microsoft 365 connected apps security: what IT admins need to know
Microsoft 365 connected apps security is now a core admin priority because OAuth permissions can create standing access to mail, files, and directory data until app grants are reviewed and revoked. Yet most Microsoft 365 security conversations still orbit the same center of gravity: passwords, MFA, and user sign-ins.
But attackers are quietly shifting one layer deeper—toward Microsoft 365 / Entra ID connected apps (OAuth).
Recent reporting based on Proofpoint research describes a pattern that’s easy to underestimate: adversaries use OAuth-based techniques to gain persistent access that can survive common containment steps like password resets, because the “access” isn’t just a login anymore—it’s a standing authorization granted to an application. TechRadar
That gap—app-based, long-lived access that slips past traditional identity cleanup—is exactly why connected apps are quickly becoming the next major exposure category. And because it’s not mainstream yet, this is the moment to get ahead of it.
If you want the practical starting point: AppGuard360 helps you inventory connected apps, identify risky permissions, and monitor for new apps and permission changes—so connected-app governance becomes routine, not reactive.
Why connected apps are different (and why normal playbooks miss them)
When a user (or admin) clicks Accept on an OAuth consent prompt, they aren’t “logging in.” They’re granting an application standing permission to access Microsoft 365 resources on their behalf—often including scopes that matter like mail, files, and directory data. If a malicious or compromised app is approved, the attacker doesn’t need to keep stealing passwords; they can keep using the authorization your tenant already granted. Proofpoint
This is why traditional containment steps can fall short. Resetting a user password may stop interactive sign-ins, but it doesn’t automatically remove previously granted OAuth permissions tied to an Entra ID enterprise application. In OAuth-abuse scenarios, the access can remain valid until you revoke the app’s permissions /grants (and invalidate related sessions/tokens as appropriate). TechRadar
AppGuard360 takeaway: The fastest way to reduce exposure is to treat connected apps like first-class identities—inventory them, review who approved them, and monitor for new high-risk permissions before they become persistent access paths.
Get ahead of connected-app risk in 10 minutes
Use our practical checklist to quickly spot risky Microsoft 365 / Entra ID connected apps (OAuth) and tighten consent before it becomes a headline in your tenant.
What “getting ahead of the curve” actually means
If you’re protecting Microsoft 365 like it’s 2019, you’re asking:
“Are users phishing-trained?”
“Is MFA enforced?”
“Do we have EDR?”
If you’re protecting Microsoft 365 like it’s 2026, you’re also asking:
Which connected apps exist in our tenant right now?
Who approved them, and when?
What permissions do they have (delegated + application)?
Do we have continuous review + alerting when new apps or risky grants appear?
Because in the real world, the “event” is often not a credential-theft headline—it’s a quiet consent, a new service principal, or a permission change nobody reviews until after damage is done. Proofpoint
Why this will become mainstream news (soon)
The techniques are already scaling. Proofpoint has documented OAuth-based tactics that enable persistent cloud access, and separate research shows a surge in OAuth device-code phishing used to compromise Microsoft 365 accounts. Proofpoint
The pattern is consistent: attackers don’t need to beat MFA if they can get your tenant to approve their access—or trick users into granting access through legitimate OAuth flows. TechRadar
What to do this week (practical, admin-realistic steps)
1) Control who can consent to apps
2) Add an admin consent workflow (so “secure” doesn’t break the business)
3) Make permission review and revocation routine—not reactive
Tip: If you clamp down on user consent without a process, you’ll create friction and shadow IT. The admin consent workflow gives users a request path while keeping approval centralized and auditable.
Where AppGuard360 fits (and why spreadsheets won’t scale)
Most teams can implement the steps above. The problem is doing them continuously—with visibility into:
New apps appearing
Permission changes (including high-risk scopes)
Stale apps with no clear owner
Consent requests piling up without review discipline
Audit questions like “who approved this, and when was it last reviewed?”
Don’t wait for connected apps to be your next breach story
AppGuard360 gives you continuous visibility and monitoring for Microsoft 365 / Entra ID connected apps (OAuth)—so approvals, permissions, and risky changes don’t slip through quarterly spreadsheets.
AppGuard360 is built specifically for the connected-app reality in Microsoft 365 / Entra ID: it helps you inventory, risk-rank, monitor change, and stay audit-ready for connected apps (OAuth)—before this becomes the incident you’re reacting to.
Bottom line
Passwords are still important—but connected apps are the access layer that often outlives passwords. If you can’t answer “who approved this connected app, what it can access, and when it was last reviewed” in under five minutes, you’re already behind the curve. TechRadar
App governance is becoming a first-class security control. The teams that operationalize it now won’t be the ones scrambling when this becomes mainstream.
Ready to operationalize connected-app governance?
Start with the checklists—or go straight to continuous monitoring. AppGuard360 helps you find risky Microsoft 365 / Entra ID connected apps (OAuth), reduce exposure, and stay ahead of the next wave of token-based attacks.