Entries Tagged "radio"

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Encryption Backdoor in Military/Police Radios

I wrote about this in 2023. Here’s the story:

Three Dutch security analysts discovered the vulnerabilities­—five in total—­in a European radio standard called TETRA (Terrestrial Trunked Radio), which is used in radios made by Motorola, Damm, Hytera, and others. The standard has been used in radios since the ’90s, but the flaws remained unknown because encryption algorithms used in TETRA were kept secret until now.

There’s new news:

In 2023, Carlo Meijer, Wouter Bokslag, and Jos Wetzels of security firm Midnight Blue, based in the Netherlands, discovered vulnerabilities in encryption algorithms that are part of a European radio standard created by ETSI called TETRA (Terrestrial Trunked Radio), which has been baked into radio systems made by Motorola, Damm, Sepura, and others since the ’90s. The flaws remained unknown publicly until their disclosure, because ETSI refused for decades to let anyone examine the proprietary algorithms.

[…]

But now the same researchers have found that at least one implementation of the end-to-end encryption solution endorsed by ETSI has a similar issue that makes it equally vulnerable to eavesdropping. The encryption algorithm used for the device they examined starts with a 128-bit key, but this gets compressed to 56 bits before it encrypts traffic, making it easier to crack. It’s not clear who is using this implementation of the end-to-end encryption algorithm, nor if anyone using devices with the end-to-end encryption is aware of the security vulnerability in them.

[…]

The end-to-end encryption the researchers examined recently is designed to run on top of TETRA encryption algorithms.

The researchers found the issue with the end-to-end encryption (E2EE) only after extracting and reverse-engineering the E2EE algorithm used in a radio made by Sepura.

These seem to be deliberately implemented backdoors.

Posted on August 26, 2025 at 7:06 AM • View Comments

Remotely Stopping Polish Trains

Turns out that it’s easy to broadcast radio commands that force Polish trains to stop:

…the saboteurs appear to have sent simple so-called “radio-stop” commands via radio frequency to the trains they targeted. Because the trains use a radio system that lacks encryption or authentication for those commands, Olejnik says, anyone with as little as $30 of off-the-shelf radio equipment can broadcast the command to a Polish train­—sending a series of three acoustic tones at a 150.100 megahertz frequency­—and trigger their emergency stop function.

“It is three tonal messages sent consecutively. Once the radio equipment receives it, the locomotive goes to a halt,” Olejnik says, pointing to a document outlining trains’ different technical standards in the European Union that describes the “radio-stop” command used in the Polish system. In fact, Olejnik says that the ability to send the command has been described in Polish radio and train forums and on YouTube for years. “Everybody could do this. Even teenagers trolling. The frequencies are known. The tones are known. The equipment is cheap.”

Even so, this is being described as a cyberattack.

Posted on August 28, 2023 at 7:05 AM • View Comments

Backdoor in TETRA Police Radios

Seems that there is a deliberate backdoor in the twenty-year-old TErrestrial Trunked RAdio (TETRA) standard used by police forces around the world.

The European Telecommunications Standards Institute (ETSI), an organization that standardizes technologies across the industry, first created TETRA in 1995. Since then, TETRA has been used in products, including radios, sold by Motorola, Airbus, and more. Crucially, TETRA is not open-source. Instead, it relies on what the researchers describe in their presentation slides as “secret, proprietary cryptography,” meaning it is typically difficult for outside experts to verify how secure the standard really is.

The researchers said they worked around this limitation by purchasing a TETRA-powered radio from eBay. In order to then access the cryptographic component of the radio itself, Wetzels said the team found a vulnerability in an interface of the radio.

[…]

Most interestingly is the researchers’ findings of what they describe as the backdoor in TEA1. Ordinarily, radios using TEA1 used a key of 80-bits. But Wetzels said the team found a “secret reduction step” which dramatically lowers the amount of entropy the initial key offered. An attacker who followed this step would then be able to decrypt intercepted traffic with consumer-level hardware and a cheap software defined radio dongle.

Looks like the encryption algorithm was intentionally weakened by intelligence agencies to facilitate easy eavesdropping.

Specifically on the researchers’ claims of a backdoor in TEA1, Boyer added “At this time, we would like to point out that the research findings do not relate to any backdoors. The TETRA security standards have been specified together with national security agencies and are designed for and subject to export control regulations which determine the strength of the encryption.”

And I would like to point out that that’s the very definition of a backdoor.

Why aren’t we done with secret, proprietary cryptography? It’s just not a good idea.

Details of the security analysis. Another news article.

Posted on July 26, 2023 at 7:05 AM • View Comments

A Device to Turn Traffic Lights Green

Here’s a story about a hacker who reprogrammed a device called “Flipper Zero” to mimic Opticom transmitters—to turn traffic lights in his path green.

As mentioned earlier, the Flipper Zero has a built-in sub-GHz radio that lets the device receive data (or transmit it, with the right firmware in approved regions) on the same wireless frequencies as keyfobs and other devices. Most traffic preemption devices intended for emergency traffic redirection don’t actually transmit signals over RF. Instead, they use optical technology to beam infrared light from vehicles to static receivers mounted on traffic light poles.

Perhaps the most well-known branding for these types of devices is called Opticom. Essentially, the tech works by detecting a specific pattern of infrared light emitted by the Mobile Infrared Transmitter (MIRT) installed in a police car, fire truck, or ambulance when the MIRT is switched on. When the receiver detects the light, the traffic system then initiates a signal change as the emergency vehicle approaches an intersection, safely redirecting the traffic flow so that the emergency vehicle can pass through the intersection as if it were regular traffic and potentially avoid a collision.

This seems easy to do, but it’s also very illegal. It’s called “impersonating an emergency vehicle,” and it comes with hefty penalties if you’re caught.

Posted on February 22, 2023 at 7:30 AM • View Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.