The Portapack is an add on for the popular HackRF SDR which allows the HackRF to be used portably without a PC. Recently the cost of this hardware duo has come down to below US$150 due to low cost Chinese clones now being available on the market. Generally the clones are of good quality too.
Once you have the hardware it is possible to install third party custom firmware such as "Mayhem" on the Portapack which enables many features such as the ability to receive and transmit various different types of RF protocols. Back in 2018 we did a review of Mayhems predecessor which was known as the "Havok" firmware. More recently Tech Minds did a video overview of Mayhem.
Now over on his blog A. Petazzoni has started a new blog series which aims to introduce the basics of the Mayhem firmware, including installation and some hands on testing with RF spoofing, denial-of-service (DoS) and replay attacks. Currently only his first post is out, and in the post he show how to install Mayhem onto the Portapack, then goes on to briefly overview some applications such as RF replay attacks, replicating wireless remote controls, receiving and transmitting POCSAG, receiving and transmitting ADS-B, and creating a jammer.
Obviously a lot of what you can do with a Portapack and the Mayhem firmware is extremely illegal and very dangerous, so please do be careful with what and where you transmit especially if you are new to RF hobby. These signals should remain in your test area only, and not leak out into the wider environment.
McAfee Advanced Threat Research have recently uploaded a blog post describing how they investigated Chamberlain’s MyQ Hub, a “Universal” IoT garage door automation platform. Such a device allows you to operate and monitor the status your garage door remotely via an app. This can allow you to open and close the garage door for couriers, or for couriers to do it themselves if they are on the app.
Whilst they found that the internet based network side was secure, they discovered a flaw in the way that the MyQ hub communicates with the remote sensor over RF radio frequencies.
Although the system utilizes rolling codes for security, McAfee researchers made use of the "rolljam" technique, which is one well known method for breaking rolling code security. The basic idea is to use an SDR or other RF device to jam the signal, collect the second rolling code after two key presses, then play back the first. Now the attacker has the second unused rolling code ready to be played back at any time.
In their threat demonstration they utilized a SDR running GNU Radio on a computing platform which sits outside the target garage door. The method used in the demonstration actually only involves jamming and not the use of a replay. It exploits a method that confuses the state of the MyQ device, allowing the garage door to be mistakenly opened by the owner when he thinks that he is closing it. They write:
With our jamming working reliably, we confirmed that when a user closes the garage door via the MyQ application, the remote sensor never responds with the closed signal because we are jamming it. The app will alert the user that “Something went wrong. Please try again.” This is where a normal user, if not in direct sight of the garage door, would think that their garage door is indeed open, when in reality it is securely closed. If the user believes the MyQ app then they would do as the application indicates and “try again” – this is where the statelessness of garage doors comes into play. The MyQ Hub will send the open/closed signal to the garage door and it will open, because it is already closed, and it is simply changing state. This allows an attacker direct entry into the garage, and, in many cases, into the home.
McAfee Advanced Threat Research Demo Chamberlain MyQ
The attacker utilises a device with full-duplex RF capabilities (simultaneous transmit and receive) to produce a jamming signal, in order to prevent the car from receiving the valid code from the key fob. This is possible as RKEs are often designed with a receive band that is wider than the bandwidth of the key fob signal (refer Figure 3, right). The device simultaneously intercepts the rolling code by using a tighter receive band, and stores it for later use. When the user presses the key fob again, the device captures the second code, and transmits the first code, so that the user’s required action is performed (lock or unlock) (Kamkar, 2015). This results in the attacker possessing the next valid rolling code, providing them with access to the vehicle. The process can be repeated indefinitely by placing the device in the vicinity of the car. Note that if the user unlocks the car using the mechanical key after the first try, the second code capture is not required, and the first code can be used to unlock the vehicle.
In his demonstrating the attack he uses the RTL-SDR to initially find the frequency that they keyfob operates at and to analyze the signal and determine some of it's properties. He then uses a Raspberry Pi running RPiTX to generate a jamming signal, and the YardStick One to capture and replay the car keyfob signal.