Show HN: Coldframe, a honeypot that poses as a supermarket fridge controller
I built Coldframe, a honeypot that pretends to be a supermarket refrigeration controller. Inspired by the events on industrial fridge installations in the past weeks, I wanted to see what people would try against a convincing fake.To learn more about this I built a honeypot that resembled perfectly the Danfoss AK-SM 800A and Dixell XWEB interfaces. Both of them are recognized on Shodan as real ones (an not as honeypots). It’s one Python file using only the standard library, and it builds on eppser/danfoss-ak-sm-decoy and public research by Synacktiv, Claroty and Ironhackers.Things that were fun to get right:- Matching real units. I used Shodan records of real devices to match header order, page titles, certificate fields and TLS versions. The Danfoss persona sends nginx headers in the same order as a real AK-SM 800A. The Dixell persona sends no Server header and pads its page to exactly 8,202 bytes.- Recognising exploit attempts. It recognises CVE-2025-41450, the Danfoss “code of the day” login bypass, and records whether the submitted code is correct for today. It also tags attempts targeting three other Danfoss CVEs and the XWEB vulnerabilities.- Letting them in. Default logins open a fake store dashboard with defrost buttons, so you see the second move, not just the first. Nothing behind it is real.Two instances have been live for a day. So far they’ve only seen generic scanners and Shodan’s crawler, which is called refrigerator.census.shodan.io.Feedback welcome, especially from anyone who has seen these devices in the field!
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If I were you, I would probably ensure that the fridges you used have residential or commercial (aka non-DC) IP addresses. Maybe Shodan uses this data for their "honeypot" label, my experience was some time ago so no idea though.
The datacenter IP is the bigger tell. Real controllers sit on shop or ISP connections. Moving one decoy onto a residential line is on my list.
Along the way I did some hunting for vulnerabilities on the Danfass units, quite interesting stuff actually.
Heh.
a supermarket has no security team. If a fridge controller needs patching, a VPN and a strong password to be safe, that work has to come from the vendor or installer by default. One would hope that all these come by default or as a feature on these devices. It could even be a selling feature and not part of an expensive maintenance contract. A supermarket manager cannot be expected to do this work.
This model has worked fine for many other types of risks.
I think this is more indicative of the plethora of technical debt and straight up technical negligence that's accompanied the past 10-15 years of internet connected everything. What's happening today is the predictable result of project based works funded by capex deploying assets (of all types) with no consideration of opex funding for the technology components.
Just because a webserver is running in some physical device (fridge, camera, vacuum, washing machine, pump controller, lighting system, audiovisual equipment, access control system etc) does not magically exempt it from the same sort of ongoing sysadmin and maintenance you'd expect as a baseline for something running on standard compute. That applies equally to manufacturers publishing firmware, and the asset owners/service companies that have the responsibility to apply.
But I keep coming back to: why do supermarkets need networked freezers anyway? Most supermarkets are open most days, with long hours. Can't any adjustments just be done manually by staff on the rare occasions when that is needed? I've seen some people argue that the major usecase is defrosting. But when you're defrosting, you certainly have lots of people on site engaged in emptying the fridge in question. Surely flipping the thermostat is a rounding error as far as costs go?
* continuous monitoring and logging of the freezer's temperature (supermarkets are obliged to do so)
* sending alerts when something's off
Regarding the defrosting: Commercial freezers can defrost while the groceries stay in, just like the "No-Frost" freezer at home.
people who target these supermarket chains etc. are doing just that. not scanning the entire internet and popping all the fridges, but doing targeted attacks.
mostly your pot will just be a +1 on benign peoples scanners.
you want honeypots for things that are mass exploited, not for things used in targeted attacks.
just my 2 cents. respect the project can be fun to do ofc but i wouldnt expect much interesting results.
that being said maybe you can find parties who secure these chains, or themselves, and offer it as a TI sort of service. Seeing as they knew about these vulns for many months before they got hit, its unlikely they will pay for it or be interested.
- Letting them in. Default logins open a fake store dashboard with defrost buttons, so you see the second move, not just the first. Nothing behind it is real.
Given the context, this reads like vomit.
> Default logins open a fake store dashboard with defrost buttons, so you see the second move, not just the first.
I think we're past the point where it's reasonable to expect people to not use AI for code, but their prose still sucks balls. You should at least write your submission here yourself, come on.
I was happy reading you post and I imagine there are many many more people like me than the grinch.
I have no idea who you are, but I would rather give you the benefit of the doubt then try to get a dopamine hit by attacking you.
If you couldn't be bothered to write it, I can't be bothered to read it.
I don't think it's unreasonable to spend literally 3 minutes writing your own submission. I'm not asking to rewrite every code comment.
And it wasn't "slightly" AI sounding text. It's very obviously AI.
MFs be doing everything but pulling those fridges off the Internet. Given the amount of TOR nodes, IP addresses today, Honeypots mean nothing ....
Of course, it's my unpopular opinion. :)
Is there a definitive story that someone actually did hack these units on a grand scale?
After that were two separate supermarket events, which I think were both linked to the known Danfoss vulnerability (CVE-2025-41450); and most recently a blood bank event.
Confirmed exploits, many manufacturers, experts, …
Given the scope here (see map at https://en.wikipedia.org/wiki/2026_French_supermarket_refrig...), it'd either be individual hackers getting inspired from their neighbor hackers, or one actor targeting European countries.
Although seemingly the hack wasn't so sophisticated, maybe it's truly just some kids fucking around with what they see being open, and maybe just want to target European countries for the "lulz" or whatever, who knows.
Would be nice but none of the other <waves at cybersecurity for the last decade> events has been.
It seems like something horrific is going to have to happen before this is taken as seriously by government and private orgs as it should have been, that seems to be how it works with other stuff historically.