What Is a Sheep Dip?
Imagine this. You’re at a client site. An employee walks in with a USB drive, saying it came in the mail and has files they need. You plug it in and, surprise! Malware has invaded your client’s network.
Everybody looks at you. Not fun.
This could have been avoided if you had a “sheep dip.”
A sheep dip is like a quarantine zone for USB drives. You scan and clean them before they touch your production network. The sheep dip is named after farmers who dipped sheep in pesticide to kill bugs before they joined the rest of the flock. In our world, it’s about stopping malware before it spreads.
What You Need to Establish a Sheep Dip
You don’t need powerful servers to make a sheep dip station. Think of it as an isolated, safe zone workstation with rules. You need:
- A dedicated PC or laptop exclusively for scanning USB devices
- Multiple up-to-date antivirus or endpoint protection products
- A system restore or clean image to reset after scans
Mark Anthony Germanos
This setup lets you inspect any USB drive separately. If the USB is infected, you will know. It never touches your production network.
Segmenting Your Network
To make a serious sheep dip, put this dedicated workstation in its own segment. The only connection should be upstream to the internet router. Make sure users do not have physical access to the box. Label the wall jack and patch panel port you’ll be using. Run a patch cable from the patch panel port directly to the router. Use a router port designated as DMZ.
By isolating the sheep dip, you protect your business from infected files jumping the gap. By connecting this between your firewall and internet router, you isolate the sheep dip from production systems and reduce risk to the internal network. The firewall views the sheep dip workstation as another computer on the internet.
Checklist to Create Your Sheep Dip
Here’s a step-by-step checklist to set up a serious USB sheep dip:
- Dedicate a PC or laptop for scanning drives exclusively
- Install and update multiple antivirus or endpoint protection products
- Verify its DHCP-allocated IP is not in any production subnet
- Create a clean system image so you can reset quickly after scans
- Create a manual or log to track scanned devices
- Perform scans only when logged in with Guest-level privileges
- Train staff to never plug unknown USBs into production systems directly
Follow this list and you’ll have a strong first line of defense.
Keeping the Herd Safe
Think of it this way: Every USB drive that walks into your shop is a potential wolf in sheep’s clothing. A sheep dip station lets you keep the herd safe without breaking the bank. Protect your clients, protect your network and sleep better knowing you’ve shut the gate on threats.
Let’s get back to the intro. If you had a sheep dip, things would have been different. You would have scanned the USB drive, determined it contained malware, and told the employee it was not safe. Thank the employee for being cautious. You’ll need a budget to make a sheep dip happen. Be proactive. You’re protecting the confidentiality, integrity, and availability of your client’s data, network, and reputation.
FAQs
Q: Why can’t I just scan the USB on my own workstation?
A: If it’s infected, malware could run before your scanner catches it. Using a separate machine shields your primary system.
Q: Does the sheep dip work for all file types?
A: The scanner checks most common files, but exotic or encrypted files may need extra tools.
Q: How often should I update the sheep dip tools?
A: Daily. Malware changes fast.
Q: Can I use virtual machines for sheep dipping?
A: Yes, but your host machine must be isolated to avoid cross-contamination. Connect the host upstream to your Internet router. If the VM detects malware, you can restore a VM snapshot within a few minutes.
Q: Do I need to keep the sheep dip offline?
A: It should be offline except when updating tools. That way even if malware runs, it can’t call out to the internet. When not in use, unplug the network cable.
Q: Can I put it on my Wi-Fi?
A: No, that’s too dangerous. Your Wi-Fi probably has production workstations, servers, or IoT (internet of things) devicesle.
Mark Anthony Germanos is vCISO and an ethical hacker with Cyber Safety Net. He has been managing computer networks since 1992. Based in the Sacramento, CA, market, he supports eight-figure businesses that handle medical and charge card data. He authored several books, including AI for Beginners and Write with AI. You can reach him at mark@cybersafetynet.net.
Featured image: DALL-E
