Tagged: unintentional emissions

Deep-Tempest: Eavesdropping on HDMI via SDR and Deep Learning

Over the years we've posted several times about the TEMPEST applications of software-defined radio. TEMPEST aka (Van Eck Phreaking) is when you listen to the unintentional RF emissions of electronics and are able to recover information from that. In the past, we posted about TempestSDR, an RTL-SDR compatible program that allows you to view images from a computer monitor or TV simply by picking up the unintentional RF emissions from it.

Usually, the images received are fuzzy and it can be difficult to recover any information from them. However recently there has been work on combining Tempest techniques with deep learning AI for improving image quality.

Deep-tempest has recently been released on GitHub and from their demonstrations, the ability to recover the true image with deep learning is very impressive. From a fuzzy grey screen, they show how they were able to recover clear text which looks almost exactly like the original monitor image.

Deep-tempest is based on gr-tempest, and requires GNU Radio, Python 3.10 and a Conda environment. Instructions for installing it are on the GitHub.

The whitepaper on the University research done to implement Deep-Tempest can be found freely on arxiv at https://arxiv.org/pdf/2407.09717.

How Deep-Tempest Works
How Deep-Tempest Works
Deep-Tempest Results
Deep-Tempest Results

EM Eye: Eavesdropping on Security Camera via Unintentional RF Emissions

Researchers from the University of Michigan and Zhejiang University have recently published their findings on how it's possible to eavesdrop and wirelessly recover images from security cameras via RF unintentionally leaking from the camera electronics.

EM side-channel attacks aka receiving and decoding data from the unintentional RF transmissions from electronics are nothing new.  In the past, we've posted how some laptops unintentionally broadcast audio from the microphone via RF, how a tool called TempestSDR can be used to spy on monitors/TV's via RF leakage, how encryption keys can be stolen from PCs via unintentional RF, and even how Disney is looking to use RF leakage for RF fingerprinting.

In their research, the team discovered that security cameras leak enough sensitive RF that an image can be recovered from the leakage over a distance. In their tests, they used a USRP B210 SDR as the receiver and tested twelve cameras including four smartphones, six smart home cameras, and two dash cams. They found that eight of the twelve leaked strongly enough for the reception of images through windows, doors, and walls. Cameras like the Xiaomi Dafang and Wyze Cam Pan 2 performed the worst, allowing for images to be recovered from distances of 500cm and 350cm respectively.

The team has not only released a paper on the topic but has also released the full code as open-source software on GitHub. The software is based on a modified version of TempestSDR, so it may also work for other supported SDRs, like the HackRF and RTL-SDR.

EM Eye: How Attackers Can Eavesdrop on Camera Videos

Demonstrating How Speakers Can Become an Unintentional RF Transmitter

Over on YouTube channel Privacy & Tech Tips has uploaded a video showing how he used an RTL-SDR to pick up RF emissions coming from some speakers that were unintentionally acting as wireless microphones. He goes on to show how you can clean up the noisy received audio in Audacity using the noise reduction filter.

I show how electromagnetic emissions from personal devices many times turn our devices into (potential) remote listening + transmitting devices when active (as demonstrated). I discovered my speakers unintentionally transmitting audio (speaker acting as microphone) to a few different frequencies via GQRX recording (computer/Pinetab microphones completely disabled).

There are a few frequencies you can tune into to listen in remotely. This includes listening in to conversations in the room as the speaker also acts as a microphone when playing sound (***tested only on my own devices***).

When the speaker volume is turned down, the signal goes down and the broadcast goes away. When the speaker volume is down, it no longer functions as a remote microphone + transmitter.

We use Audacity to clean up the audio. GQRX is used to record the signals which are filtered on the Pinetab with internal RTL-SDR. Audio processing/noise reduction done running Parrot Linux using Audacity.

We touch on the fact all electronic devices give off their very own unique electromagnetic emissions which can act as device signatures (strength depends on shielding).

Sometimes speaker wire not properly shielded (as is found in most PC's) can act as a radio transmitter antenna without user knowledge. Here I discovered a few frequencies broadcasting the audio live (.25 second delay for SDR modulation).

📡 Laptop Speakers Are Transmitting (Radio) Microphones

Video Tutorial on Debugging RF Emissions on a Circuit Board with an RTL-SDR

Over on the Hackaday YouTube channel a video by Alex Whittemore has been uploaded showing how to do some basic RF emissions debugging. When creating electronic products it's important to ensure that there is no unintentional RF leakage in excess of emissions standards, and there is often a need to debug a circuit board to determine exactly what part or areas are generating excessive RF noise. To do this expensive EMC analyzers and near field probes are typically used.

Alex's tutorial video shows us how we can create a low cost home made EMC probe using an RTL-SDR, LNA and home made near field probe made out of magnet wire. The video starts by explaining RF compliance, demonstrating some higher end equipment, then moves on to showing how to build a probe yourself, before finally demonstrating it being used on some circuit boards. For software, he uses SDRAngel and QSPectrumAnalzyer which are preinstalled on a DragonOS image. 

The Hacakday.io project page has the tutorial in text and the video slides can be found here.

In the past we've also seen another post about home made EMC probes, and how to combine this idea with OpenCV to create noise heatmaps of circuit boards.

Basics of RF Emissions Debugging: Alex Whittemore

YouTube Tutorial: Spying on Computer Monitors with TempestSDR

Over on YouTube SignalsEverywhere (aka Corrosive) has uploaded a tutorial video showing how to use TempestSDR with an Airspy SDR. Back in November 2017 we posted about how we were able to get TempestSDR to run with an RTL-SDR, Airspy and SDRplay, and showed some results. Since then several people have managed to repeat our results, but many have also had trouble understanding how to make TempestSDR work and what all the settings are for.

TempestSDR is an open source tool that allows you to use any SDR that has a supporting ExtIO (such as RTL-SDR, Airspy, SDRplay, HackRF) to receive the unintentional signal radiation from a screen, and turn that signal back into a live image. This can let you view what is on a screen without any physical connections.

Corrosive's tutorial video shows us how to tune the signal in the TempestSDR software in order to receive a clear image as well as showing the software in action.

How to Spy on Computer Monitors | TempestSDR Tutorial (with an Airspy)

Using an RTL-SDR and TEMPEST to attack AES

All electronic devices emit some sort of unintentional RF signals which can be received by an eavesdropping radio. These unintentional signals are sometimes referred to as TEMPEST, after the NSA and NATO specification which aims to ensure that electronic devices containing sensitive information cannot be spied upon through unintentional radio emissions, sounds or vibrations. TEMPEST can also refers to the opposite, which is spying on unsecured electronic devices by these means.

Recently the team at Fox-IT, a cybersecurity specialist company has released a paper showing how an RTL-SDR can be used as a TEMPEST attack device to help recover AES-256 encryption keys (pdf) from a distance by utilizing unintentional RF emissions. AES is an encryption standard commonly used in computing with protocols like HTTPS (e.g. with online banking) and for securing WiFi networks.

In their experiments they set up an AES implementation on an FPGA, and used a simple wire loop antenna and RTL-SDR to measure and record the RF emissions. By then doing some analysis on the recorded signal they are able to fairly easily extract the AES encryption key, thus defeating the encryption.

Further testing in an anechoic chamber showed that with a discone antenna they were able to recover the keys from up to a meter away. A directional antenna could probably reach even further distances.

In the past we’ve seen a similar attack using a Funcube dongle, which is an SDR similar to the RTL-SDR. In that attack they were able to remotely recover encryption keys from a laptop running GnuPC. Also, somewhat related is Disney’s EM Sense which uses an RTL-SDR to identify electronic devices by their RF emissions.

[Also seen on Hackaday]

Fictional scenario involving a hacker recording RFI from a remote PC.
Fictional scenario involving a hacker recording RFI from a remote PC.

USBee: Leaking Data from Air-Gapped Computers and Receiving it with an RTL-SDR

This Monday researchers from Ben-Gurion University of Negev released an academic paper detailing their research in showing how attackers could cause your PC to wirelessly leak data. They write that usually covertly modified USB devices are required to leak data, as is the case with the NSA’s COTTONMOUTH device which is detailed in their ANT catalog. However, the innovation from these researchers is that their own implementation can be used to turn any unmodified USB device into a make shift transmitter.

The attack works by first infecting a computer with their malware software. The malware then utilizes the USB data bus to create electromagnetic emissions on a connected USB device. In these tests they use a USB flash drive and write a file to the device in such a way that the emissions produced are transmitting decodable data. They write that any binary data can be modulated and transmitted to a nearby receiver, such as an RTL-SDR dongle. Data rates can reach up to 80 bytes/s.  The data is modulated with binary frequency shift keying, and their receiver code is implemented in GNU Radio.

This story has also been featured on arstechnica and threatpost. The video below demonstrates the attack.

USBee: Jumping the air-gap with USB