Cybercriminals are getting smarter and their latest trick is catching even tech-savvy users off guard. A new wave of PDF phishing scams is targeting inboxes across industries, and instead of asking you to “click a suspicious link,” these scams are convincing you to pick up the phone.

From early May to early June 2025, Cisco Talos researchers reported a sharp rise in these attacks, with scammers impersonating trusted brands like Microsoft, Adobe, and DocuSign. The twist? They’re using callback phishing and it’s proving dangerously effective.

What Is Callback Phishing and Why It Works

Traditional phishing attacks trick you into clicking a malicious link. Callback phishing flips the script by making you initiate the contact.

Here’s how these PDF scams work:

  1. You get an email with a PDF attachment that appears to come from a reputable company.
  2. Inside the PDF, there’s a message about a supposed issue — like a subscription renewal — along with a phone number for “tech support.”
  3. Thinking it’s safe to call, you dial the number.
  4. On the other end, a convincing “support agent” asks for sensitive data or guides you to install malicious software.

By removing the risky click and replacing it with a phone call, attackers bypass many traditional email security filters — and gain your trust faster.

Why PDF Phishing Scams Are So Dangerous

This method works because:

  • No obvious malware in the email — making it harder for security software to flag.
  • Social engineering over the phone — scammers sound professional and use real company lingo.
  • Familiar brands as bait — giving instant credibility to their requests.

For businesses, the consequences can be severe — from stolen credentials to ransomware infections.

How to Protect Your Business From PDF Phishing Attacks

If your business relies on email communication with vendors, clients, and partners, you’re a prime target. Here’s how to defend against these scams:

  • Never trust PDF attachments from unknown senders especially if they urge you to call a number.
  • Verify support numbers directly from the official company website.
  • Train employees to recognize phishing tactics and fake support scams.
  • Deploy advanced email security that flags suspicious attachments and scans PDFs for hidden threats.
  • Use a managed IT security partner like Intelecis to monitor, detect, and block these evolving attacks before they reach your team.

The Intelecis Advantage: Stop Scams Before They Reach Your Inbox

At Intelecis, we specialize in advanced threat detection and phishing prevention. Our white-glove IT and cybersecurity services include:

✅ 24/7 email threat monitoring and filtering
✅ Ongoing employee phishing awareness training
✅ Real-time incident response to suspected fraud attempts
✅ Advanced protection against social engineering attacks

PDF scams may be evolving, but so are we and with Intelecis on your side, your business stays one step ahead of cybercriminals.

Bottom Line:
The safest call you can make isn’t to the number in a shady PDF it’s to a trusted IT partner who knows how to stop these scams before they start.

Schedule your free cybersecurity assessment with Intelecis today.