🎯 The Threat: Microsoft Device Code Phishing

Microsoft has recently issued a warning about a sophisticated phishing attack that takes advantage of its own legitimate login system. It’s called device code phishing, and it’s being used to trick employees into giving away account access — even with MFA enabled.

Unlike traditional phishing, which uses fake login pages or spoofed websites, this one leverages real Microsoft login screens to create a false sense of security.

🔍 How It Works

1. It starts with a convincing email — maybe an invite to a Microsoft Teams meeting or a document share.
2. You’re asked to enter a short device code on a real Microsoft login page.
3. What you don’t realize: That code is tied to the attacker’s device, not yours.
4. By entering it, you log them in — not yourself.

Because the login is legitimate, it often bypasses MFA and slips past most security tools unnoticed.

Even worse, once the attacker is in, they may capture your session token — a digital key that keeps them logged in behind the scenes, even if you change your password.

🚨 Real Impact for Small Businesses

Imagine handing over access to your Microsoft 365 account — email, files, contacts, Teams chats — without even realizing it. That’s exactly what this attack enables.

Once inside:

• Attackers can read sensitive emails

• Download company files

• Impersonate you to trick others (CEO fraud or lateral phishing)

• Maintain access undetected for weeks or months

This type of breach can cost small businesses tens of thousands in downtime, compliance violations, and lost trust.

🛡️ How Check Your Six Locks This Down

We don’t just react — we prevent.

Our team configures and monitors Microsoft environments to close down this attack vector entirely. Here’s how:

✅ Disable Unused Device Code Login

If your business doesn’t use this feature, we shut it down at the tenant level.

✅ Restrict Access to Trusted Devices & Locations

Our conditional access policies block login attempts from unfamiliar IPs, devices, and geolocations.

✅ Detect & Respond to Suspicious Behavior

We implement behavioral analytics to flag unusual login activity — even from valid credentials.

✅ Train Your Team (and Test Them)

Our awareness training teaches your staff to spot phishing emails and device code traps. We can even run simulated attacks to prove your defenses work.

✅ Session Control

We monitor and revoke rogue session tokens so hackers can’t stick around silently.

📢 Warning Signs to Watch For

• You’re asked to enter a short “device code” from an email

• The login screen looks normal but the request feels out of place

• The request isn’t part of your regular login process

Pro tip: Real Microsoft logins don’t usually involve entering a code someone else sends you. If in doubt, pause and verify — via a separate message, phone call, or internal chat.

💬 Don’t Wait Until It Happens

Even sophisticated users can fall for this — the emails are clean, the login page is real, and the code seems harmless. That’s why device code phishing is so dangerous — and why proactive defense is critical.

✅ Let’s Lock It Down — Together

At Check Your Six, we specialize in protecting San Jose and Bay Area businesses from emerging threats like this. From Microsoft 365 hardening to endpoint protection and full threat response, we’ve got your six.

📞 Schedule a free Cybersecurity Risk Assessment today.
🔒 Let’s make sure you’re protected — before someone else gets in.