Mini Spy Bug Walkthrough

What we like most about [GreatScott’s] project videos is that he not only shows making them but also the calculations for selecting parts and the modifications along the way. This time he’s made a mini spy bug that records up to nine hours of audio.

His first task was to figure out if the ATmega328p’s ADC is suitable for audio sampling, but only after he explains how sampling works by periodically checking the input voltage from the microphone. Checking the datasheet he found that the ADC’s fastest conversion time is 13 microseconds, which works out to a sampling rate of 76.923 kHz. Good enough.

He then walks through why and how he decided to go with a pre-made amplifier circuit built around the MAX9814 IC. Spoiler alert. His electret’s amplifier output voltage was too low, using an off-the-shelf circuit instead of making his own kept things simple, and the circuit has automatic gain control.

At this point, he added the MicroSD card adapter. Why not just transmit the audio over FM as so many others have done with their hacks? Perhaps he’s worried about someone detecting the transmission and finding his bug.

His final optimization involved getting a good battery life. He measured the circuit’s current draw at 20 milliamps. With a 160 mAh battery capacity, that would be 8 hours of recording time. Removing the Arduino Pro Mini’s voltage regulator and two LEDs got the current down to 18 milliamps and a recording time of 9 hours. Better.

Those are the highlights. Enjoy his full walkthrough in the video below.

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Hack Your Own Samsung TV With The CIA’s Weeping Angel Exploit

[Wikileaks] has just published the CIA’s engineering notes for Weeping Angel Samsung TV Exploit. This dump includes information for field agents on how to exploit the Samsung’s F-series TVs, turning them into remotely controlled spy microphones that can send audio back to their HQ.

An attacker needs physical access to exploit the Smart TV, because they need to insert a USB drive and press keys on the remote to update the firmware, so this isn’t something that you’re likely to suffer personally. The exploit works by pretending to turn off the TV when the user puts the TV into standby. In reality, it’s sitting there recording all the audio it can, and then sending it back to the attacker once it comes out of “fake off mode”.

It is still unclear if this type of vulnerability could be fully patched without a product recall, although firmware version 1118+ eliminates the USB installation method.

The hack comes along with a few bugs that most people probably wouldn’t notice, but we are willing to bet that your average Hackaday reader would. For instance, a blue LED stays on during “fake off mode” and the Samsung and SmartHub logos don’t appear when you turn the TV back on. The leaked document is from 2014, though, so maybe they’ve “fixed” them by now.

Do you own a Samsung F-series TV? If you do, we wouldn’t worry too much about it unless you are tailed by spies on a regular basis. Don’t trust the TV repairman!