Email Attachment Security Insights From a Veteran Network Administrator

I’m writing this post after three cups of coffee—there’s just something about the caffeine kick that makes my mind sharper, especially when it comes to email security. Having been a network admin back in 1993 (yeah, the PSTN days and early days of dial-up) and having seen the mess the Slammer worm made back over voice and data mux, let me tell you one thing, email attachments have always been one of the primary vectors for data theft by attackers. It’s almost as if the bad guys never stopped.

So here we are a few decades down the road and phishing emails with malicious attachments are still one of the biggest threats for data breaches. If you like to run a business — or heck, even if you’re a home user who thinks you’re safe here — you need to know how attackers take advantage of email attachments and what you can do about it.

Cyber Kill Chain How Attackers Use Email Attachments

Here’s the thing. Hackers no longer simply send a virus in an attachment — their playbook has been upgraded. A tactic that I see often (and recently assisted three banks defending against during zero-trust architecture upgrades) is the use of maliciously crafted attachments that peacefully look like Word or Excel files but carry payloads to covertly open backdoors or siphon data.

Common Attack Techniques Using Email Attachments

• A Word or Excel file that seems harmless but that contains macros that run malicious scripts
• Reader exploits with malicious PDF files
• Compressed files (.zip, .rar) with encrypted payloads that evade scanners

And don’t even get me started on how attackers forge the actual sender to convince you that it’s your CEO or trusted vendor. In those early days of PSTN security, it seemed easier. The sophistication now is insane.

Remember the Slammer worm? That thing spread much, much too quickly just by exploiting servers, but email attachment attacks today are like a silent poison — slow, stealthy, and hard to recognize until it’s too late.

The goal? To convince you to click on that attachment. Once it’s open, malware can steal credentials, copy sensitive files or even load up ransomware. At times it’s downright artful social engineering. It’s often a weaponized file that leverages an unpatched vulnerability.

Email Encryption Best Practices

OK, so preventing bad attachments from being sent is the first piece — but what about the attachments you send? This is where encryption is a must.

First here, I am always suspicious (perhaps a little bitter) of anything touted as being AI-powered encryption — there’s a lot of snake oil out there. What actually does the trick is strong basic encryption standards, together with good key management.

Encryption Recommendations

• End-to-end encrypt your email, ideally with something like S/MIME or PGP
• Verify that your email gateway encrypts attachments in transit and at rest
• Create rules to enforce encryption for emails with sensitive data
• Prepare your users — because the best tech fails if the user hits send on an unencrypted, confidential file

As someone who worked on the upgrades of the zero-trust architectures of the banks, mandating encrypted email communication changed everything. However sneakily attackers try to pot shot users, those attachments which are encrypted are extremely more difficult to intercept and read.

Detection of Malicious Software and File Scanners

But you can encrypt emails until the cows come home. But if you allow malicious files to slip through, encryption won’t save your bacon.

PJ Networks deploys Fortinet’s email security solutions, scanning every email attachment (yes, every one) using a combination of signature-based detection, sandboxing and behavior analytics.

Why do we love Fortinet here? Because it’s flexible and can easily plug into whatever you already had going on—and it doesn’t crush your mail servers or bog your workflows down.

Key Benefits of Fortinet Email Security

• Scanning of attachments in real-time for both known and zero-day threats
• Automatically quarantine or block suspicious files
• Support for scanning of encrypted attachments (important, as attackers typically attempt to bury payloads further in encrypted zips)

I will do come clean, I used to pull out my hair busting malware in email attachments years ago. Not to mention freeing up your team to work on better things than firefighting via automated systems.

Secure Email Solutions from PJ Networks

I own my own security company: I’ve got skin in the game. We don’t just provide gear—we design solutions.

Our technology stack for email security at PJ Networks Pvt Ltd is based on Fortinet technology plus additional custom policies to suit the risk profile for each of our clients.

Our Approach to Email Security

• Scan and encrypt all incoming/outbound attachments
• Issue strict attachment size and type controls
• If possible implement email DLP (Data Loss Prevention) to stop sensitive data from leaving the organization
• Augment with user training — because technology on its own is not the panacea for human error

And of course we have real-world threat intelligence from events like DefCon — I just returned from the hardware hacking village, and I’m loaded up with actionable ideas for protecting endpoints against stealthy access via email chains.

I’m old school in some respects but I’m always learning. That combination — that long-haul experience with the cutting edge — is why our clients trust us to protect millions of emails a day.

Conclusion

The bottom line: Email attachment-based attacks are not going to disappear. They’re evolving. And your defenses must evolve with them or, frankly, you’re inviting trouble.

I’ve lived in the trenches since 1993. After PSTN mux nightmares, weathering the Slammer worm, and now doing battle with what banks are facing now upgrading their zero-trust policies, I cannot overemphasize enough the importance of strong encryption, vigilant scanning and a security culture that gets it.

You can fall into the trap that with your mail server’s spam filter, you are covered.

My last bit of counsel (after three cups of coffee, no less):

• Assume email attachments are poisonous until proven otherwise
• Always encrypt sensitive communications
• Advanced scanning — period
• Beat your team relentlessly on training. People Are Your First Line of Defense, Not Just Your Last

There’s no magic pill, but layered defense conquers all. If you seek support — true support — then ask. With the tools—and the know-how—PJ Networks can secure your email system tight.

Stay safe out there. Sanjay.