The Alert Fires, but Nothing Actually Stops It
If you run Huntress or a similar detection tool on Microsoft 365, you've probably seen it: a login flagged as coming from a free VPN service. The alert tells you something happened. It doesn't tell you how to make it stop happening. As one IT admin recently described on Reddit, the tooling flags free VPN usage on M365 accounts, but there's no clean, automated way to block it — just manual remediation, account by account, alert by alert.
For a solo IT admin or a small MSP juggling dozens of tenants, that's not a workflow. That's a treadmill. And treadmills don't stop attackers — they just tire out the humans watching the dashboard.
Detection Without Blocking Is a Half-Finished Job
Detection tools are valuable because they surface anomalies you'd otherwise miss. But visibility isn't containment. If your only response to a flagged free VPN login is to manually disable a user, reset a password, and hope you caught it before damage was done, you're always operating a step behind the attacker.
This gap matters more than ever because credential theft has become the primary way attackers get in front of your identity layer in the first place. According to The Hacker News, the Lunex Stealer malware abuses a legitimate AMD driver to disable security monitoring and steal browser-stored credentials — including saved M365 passwords and session tokens. Once an attacker has those credentials, routing the login through a free VPN or anonymizer is a simple, well-worn move to defeat geo-based and IP-reputation detection.
The pattern doesn't stop at credential theft. It's part of a larger trend of attackers exploiting identity and access gaps that organizations aren't actively watching. A recent case of ghost service accounts enabling M365 data theft in Chile showed how forgotten, unmonitored access paths become the exact channel attackers use to exfiltrate data undetected. Similarly, according to The Hacker News, JADEPUFFER-linked attackers used compromised service principals to delete Azure resources — another example of identity and access controls being the actual battleground, not just the perimeter firewall. Free VPN logins on M365 are the same category of problem: an access gap that detection alone can't close.
How to Actually Block It: Conditional Access, Not Manual Cleanup
The real fix isn't a better alert. It's a policy that prevents the login from succeeding in the first place. Microsoft 365 (via Entra ID / Azure AD Conditional Access, which requires at least a P1 license) lets you build rules that block sign-ins based on location, IP reputation, device compliance, and risk signals — automatically, every time, without a human watching a queue.
Here's the practical approach for small IT teams:
- Enable named locations and IP ranges. Define your trusted office IPs and known remote-work locations. Anything outside that list can be treated as higher risk.
- Use Microsoft Entra ID Protection risk policies. These use Microsoft's threat intelligence to flag and block sign-ins from anonymizer networks and known malicious IP ranges — including many commercial free VPN exit nodes.
- Require compliant or hybrid-joined devices for access. Attackers routing through a VPN from an unmanaged device won't pass this check even if they have valid credentials.
- Layer in phishing-resistant MFA. Passkeys or certificate-based auth close the gap that password-only or SMS MFA leaves open, a topic we've covered in detail in our guide to passkeys vs SMS MFA before the 2026 deadline.
- Set the policy order correctly. Conditional access rules evaluate in a specific way, and a misordered policy set can leave holes even when every individual rule looks correct — we break down the right sequence in our post on conditional access policy setup order for small business.
Once these policies are live, a flagged free VPN login isn't just visible in a dashboard — it's rejected at the door. That turns your detection tool from a to-do list generator into a confirmation system.
Don't Forget the Bigger Identity Picture
Blocking VPN-routed logins is one control, not the whole strategy. Attackers who can't get in through the front door will look for side doors: stale service accounts, over-permissioned integrations, and unmonitored identity paths. If you haven't audited your tenant for these gaps recently, our overview of identity threat detection for small business is a good next stop to make sure conditional access isn't the only layer standing between you and an incident.
Take Action
Alerts are only useful if something acts on them. If you're not sure whether your M365 tenant has conditional access gaps, stale identity paths, or exposed configurations that attackers could exploit before your detection tool even fires, a proactive scan will tell you before an attacker does. Oscar Six Security's Radar scan is $99 and gives small business IT admins and MSPs a clear, prioritized view of exposure — no enterprise contract required. Check your exposure with Radar.
Focus Forward. We've Got Your Six.