A new wave of phishing emails disguised as invoices are tricking Gmail and Google Workspace users. These emails often look real, bypass spam filters, and ask the recipient to click a link. That link leads to a fake login page or a malicious Google app authorization. Once the victim types in their credentials or grants access, attackers gain control of their Gmail.
This article breaks it down in simple words, shows how to check if your Workspace account is safe, and gives step-by-step protection tips.
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What is the "invoice hack" and how does it work?
Attackers send an email that looks like an invoice. When clicked, the link takes the user to a fake Google login page or an app request page.
- If you type your password, the attackers steal it.
- If you approve the app, attackers gain a token that lets them keep accessing your emails without needing your password.
Explained like you're five
Imagine you get a letter that says "Pay this bill." There's a door inside the letter, and you put your key (your Gmail password) in it. But the door is fake—it belongs to a thief. Now the thief has your key and can sneak into your room (your Gmail) whenever they want. Sometimes the thief even asks you for a master key that never expires (an app permission).
How Workspace users can check if they are safe or hacked
Red flags in Gmail and account activity
- Emails sent from your account you didn't write.
- Forwarding rules you didn't create.
- Logins from strange countries or devices.
- New "apps" connected to your account you didn't approve.
- Security notifications about changes you didn't make.
Quick safety checklist
- [ ] Check account activity in Gmail ("Last account activity" or myaccount.google.com/security).
- [ ] Review connected apps and remove unknown ones.
- [ ] Look for new filters or auto-forwarding in Gmail settings.
- [ ] Review devices and sign out of unknown ones.
- [ ] Change your password and turn on 2FA if unsure.
How to protect Gmail and Workspace accounts
Admin-level defenses
- Enforce 2FA for all users, ideally with physical security keys.
- Restrict OAuth app access so only verified apps can connect.
- Enable alerts for suspicious logins and new forwarding rules.
- Configure SPF, DKIM, and DMARC to block spoofed invoices.
User best practices
- Don't click invoices you're not expecting. Confirm with the company directly.
- Use a password manager (they won't auto-fill credentials on fake sites).
- Prefer security keys (FIDO2) over SMS for 2FA.
- Double-check the URL before typing your Google password.
What to do if you suspect a hack
- Sign out everywhere from Google account security.
- Change your password immediately.
- Remove any unknown connected apps (OAuth).
- Delete strange Gmail filters or auto-forwarding rules.
- Turn on strong 2FA (preferably with a hardware key).
- Call us immediately, we'll reset, revoke hacker access, and secure your Workspace.
If attackers have persistent tokens, admins must revoke them for full cleanup.
Quick defense comparison
| Option | When to use | Pros | Cons |
|---|---|---|---|
| Security Keys (FIDO2) | High-value accounts | Strongest protection | Cost per key |
| Authenticator App | Most users | Easy to deploy | Still phishable |
| SMS 2FA | Basic fallback | Better than nothing | Weak vs SIM swap |
| OAuth Blocking | Admin action | Stops rogue apps | Needs setup |
Conclusion & Next Steps
Invoice phishing emails are a serious threat because they look real, sometimes even using Google's own tools to appear legitimate. The good news: with awareness, stronger login protection, and admin controls, you can shut down these attacks.
Call to Action: If you suspect a hack, call us right away. We'll reset your account, block hacker access, and clean up any hidden traps.
Internal Links (Blogger)
Suggested External Links
- Doppel Intelligence, Report on Google Sites & OAuth phishing.
- Tom's Hardware, Study on phishing targeting Gmail & Gemini.
- Identity Theft Center, Guide on invoice phishing scams.
FAQs
Q1. Can I recover my Gmail if hackers got in?
Yes, change your password, revoke apps, and enable 2FA. Admins may need to revoke persistent tokens.
Q2. Why do fake invoices arrive if I didn't buy anything?
It's a trick: attackers send "urgent" bills to pressure you into clicking.
Q3. Doesn't Google block this?
Often yes, but attackers use valid signatures or Google infrastructure to sneak past filters. That's why extra protection is key.
References
Doppel Intelligence, Phishing using Google Sites & OAuth.
Tom's Hardware, Phishing using Gemini/Workspace flaws.
Identity Theft Center, Invoice phishing scam guide.
Trend report on phishing 2025.
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