The Innocent Auto-Reply That Opens the Door to Hackers
It's summer. You've set your out-of-office message, booked your flights, and handed off your responsibilities. Your auto-reply goes out to anyone who emails you:
"Hi, I'm out of the office from June 28 to July 5. For urgent matters, please contact my assistant Sarah at sarah@company.com or call our office at (804) 555-0100. I'll respond when I return."
Seems harmless, right? To a cybercriminal, this message is a goldmine.
What Hackers Learn From Your Vacation Auto-Reply
A well-crafted (but naively written) out-of-office message hands attackers exactly the information they need to launch a targeted attack:
- You're away — and won't be monitoring your email or able to quickly verify suspicious requests
- The exact dates — attackers know precisely when to strike and how long they have
- Who covers for you — now they know Sarah is the person to impersonate or social engineer
- Your phone number — useful for voice phishing (vishing) attacks or SMS scams
- Your organization's email format — combining your name format with the domain, attackers can now guess other employee email addresses
- Urgency leverage — "urgent matters" framing tells attackers which emotional hooks to use on your team
How Attackers Use This Information
Business Email Compromise (BEC)
Once an attacker knows you're away, they may impersonate you in emails to your colleagues or finance team. "Hi Sarah, I'm in a meeting and can't call — can you process an urgent wire transfer to this account?" The combination of urgency, your absence, and the financial context makes this devastatingly effective.
Spear Phishing Your Backup Contact
Your alternate contact — Sarah, in our example — is now a direct target. Attackers may email Sarah pretending to be a vendor, client, or partner, knowing she's handling increased responsibilities and may be less vigilant than normal.
Reconnaissance for Future Attacks
Even if attackers don't strike immediately, your auto-reply feeds their target database. They now have validated email addresses, organizational structure, phone numbers, and schedule information that makes future attacks more effective.
How to Write a Safer Vacation Auto-Reply
You can still set an out-of-office without giving hackers a roadmap. Here's what to change:
❌ Don't Include:
- Specific return dates (say "next week" or "shortly" instead)
- Alternate contact names and email addresses in the external auto-reply
- Your personal phone number
- Detailed context about your absence ("I'm at a conference in Las Vegas")
✅ Do Include:
- A general acknowledgment that you're temporarily unavailable
- A general office phone number (not a direct line to a specific person)
Sample Safer Auto-Reply:
"Thank you for your email. I'm currently out of the office and will respond upon my return. For immediate assistance, please call our main office at (804) 555-0100."
Set Two Different Auto-Replies
Microsoft 365 and most email platforms allow you to set separate auto-replies for internal senders (colleagues) versus external senders (everyone else). Consider giving colleagues more detail while keeping the external reply minimal.
Train Your Team — Not Just Your IT Department
Cybersecurity awareness for Richmond and Chester VA businesses isn't just about technology — it's about people. Every employee with a company email address is a potential attack vector. Training your team to recognize social engineering, BEC attempts, and phishing is just as important as deploying the right security tools.
Yesteck provides security awareness training and simulated phishing exercises for businesses throughout the Richmond metro area as part of our managed IT and cybersecurity programs.
Talk to Yesteck about protecting your business from social engineering attacks.