Your Helmholz REX 100 Has a Critical Problem. Here’s the Fix.

Oye, mi gente, let’s have a serious talk. Pour a little coffee and listen up, because this is important for anyone working with industrial systems. We’re talking about a popular piece of equipment, the Helmholz REX 100 router, which is like a digital gatekeeper for many factories and plants. The problem? For a while, this gatekeeper was leaving the front door unlocked and the keys hanging right by the knob.

This isn’t just some small bug, amigos. Researchers found a whole collection of serious security holes in these devices. Imagine a guard who can be tricked into giving a stranger the master key, or who freezes up if you shout at him too much. That’s what was happening here. These vulnerabilities could let a bad actor, a cyber-bandido, walk right into a factory’s control network. From there, they could shut things down, steal secrets, or cause real chaos.

But don’t worry. The story has a good ending. The problems have been fixed. My job today is to tell you straight what the problems were, how the bad guys could use them, and exactly what you need to do to protect yourself. Vamos.

The Fiesta of Flaws: What Was Wrong with the REX 100?

The security researchers found not just one, but a whole series of problems, some of them very, very bad. They gave them all official CVE numbers, but let’s break it down into simple terms.

The Open Door (Unauthenticated RCE): This was the big one, de verdad. There was a way for an attacker on the network to send a special command to the router and get complete control, what we call root access. No password, no login, nothing needed. ¡Qué malo! They also found hard-coded, secret administrator accounts with passwords that couldn’t be changed. It’s like having a hidden back door that only the bad guys know about.
The Insider Trick (Authenticated Command Injection): Even if an attacker needed a password, things were still not good. If they could get a login, even a low-level one, they could trick the router’s web page into running malicious commands. So they might get in as a simple user but trick the system into making them the boss.
Making a Mess (Denial of Service): Other flaws allowed an attacker to basically scream at the router by sending it tons of junk requests. This would overwhelm the poor device, causing it to freeze and stop working until someone manually rebooted it. Imagine your whole factory’s remote connection going blind because of this. Not good.
Stealing Secrets (Info Leaks & XSS): Finally, there were problems that let a logged-in attacker steal information. They could pull the router’s configuration, which might contain sensitive VPN passwords. Another bug allowed them to inject malicious code into the web management page to hijack an administrator’s session.

When you put all these things together, you have a device that was, frankly, very vulnerable. And because these routers are often the bridge between a company’s office network and its critical factory floor network, compromising it is a very big deal.

How the Bandidos Could Attack

So you might be thinking, “This sounds bad, but could a hacker really do this?” The answer is yes, and sometimes, it would be fácil.

The biggest gift to an attacker was the default password. Many of these routers were installed and nobody ever changed the factory password from “admin” or something similar. An attacker could just try that, log in, and then use the command injection flaws to take over completely. ¡Por favor, mi gente, always change the default passwords on everything!

Even without a password, an attacker on the same local network could use the “Open Door” flaw to gain control. And if a company made a mistake and connected the router’s management page directly to the internet, then any hacker in the world could find it and attack it. They scan for these things all day, every day.

Once they are in control of the router, ¡zas!, the game is over. They are now at the gateway of your operational technology (OT) network. They can:

Spy on your industrial processes.
Disrupt operations by sending bad commands to your machinery.
Pivot and move deeper into your network.
Install malware to create a permanent backdoor for themselves.

The researchers also warned about a “cloud hop” scenario. These routers connect to the myREX24 cloud portal. If a hacker could compromise one router, they might be able to use that trusted connection to attack the cloud, or use the cloud to attack other routers. It could create a dangerous chain reaction.

La Solución: How to Fix It and Stay Safe

Okay, enough of the scary talk. Let’s get to the solution, because there is a clear one, gracias a Dios. Helmholz, the company that makes the router, worked with the researchers and has released patches. Here is what you must do.

UPDATE YOUR FIRMWARE! This is the most important step. I cannot say it enough. You need to make sure your REX 100 router is running firmware version 2.3.3 or newer. This version fixes all the known problems we talked about. All of them. If your router is connected to the myREX24 cloud portal, you can even update it remotely. Check your devices. Do it yesterday.
CHANGE YOUR PASSWORDS! I said it before, and I will say it again. Use a long, strong, unique password for your router. If you are still using the password it came with out of the box, you are inviting trouble.
SEGMENT YOUR NETWORK! A device like this should not have its management page exposed to the open internet. Put it behind a firewall. Restrict who on your network can even talk to it. Treat it like the critical piece of infrastructure it is.
MONITOR YOUR SYSTEMS! Keep an eye out for strange behavior. If a device reboots unexpectedly or you see weird network traffic, investigate it. It could be a sign that something is wrong.

The Big Lesson for Our Industry

This story is more than just about one router. It is a wake-up call for the entire industrial world. The devices that connect our factories to the outside world are high-value targets. We cannot just plug them in and forget about them.

Security must be part of the entire lifecycle, from buying the device to installing it and maintaining it. We must demand secure products from vendors, and vendors must respond quickly when problems are found, just as Helmholz did here. Their cooperation with the researchers and CERTs was a good thing to see.

For us, the operators and defenders, it means we have to be vigilant. We need to do the basics right: patch our systems, use strong passwords, and build strong network defenses. These simple things are our best protection.

So, go check your systems. Make sure you are patched and protected. Stay safe out there, amigos.