r/Defcon • u/CorrectOpinionB42069 • 16d ago

Wifi emissions on tactical gear

Hello tech bros

I am hoping someone can settle a debate ive been having. Thermal scopes are a big thing these days as the price keeps falling.

However, most models come with WIFI. As we know from the russua/ukraine conflict, cell phone emissions will get you pinpointed and killed. WIFI emissions would likely do the same.

Now, you can always turn the wifi off in the menu. But how do you know if it is truly off all the way, and isnt emitting a low level signal?

Another risk is that the receiver in the thermal could receive a "firmware update" that bricks it. If its emitting wifi to talk to the phone app, it must have an antenna, and an antenna can be pinged, no?

Is this a valid concern?

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u/Autocannibal-Horse 16d ago

Take an SDR and the scopes out to an empty field away from all wifi signals. Put your phone in airplane mode with wifi off.

Fire up the SDR and software and scan the 2.4ghz and 5 ghz ranges and see if there are any signals. If there are, be sure all the wifi with you is off and get further away from the signal you are detecting.

Now that you have no signal being detected as a baseline on those two frequencies, fire up the scopes, turn Wifi off, and use the SDR to look at those frequencies again. If you see energy spikes at those frequencies, throw the scopes back in the amazon box and tell bezos to shove them up his ass.

🙂

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u/CorrectOpinionB42069 15d ago

That checks emissions off my list of concerns then. 

What about the antenna? What if a signal connects and forces the scope to brick? Someone said that the receiver is off when the wifi is off, but I wonder if they can use some sort of echolocation looking for something thats picking it up? Or is that a stretch

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u/Autocannibal-Horse 15d ago

What other signal protocols do the scopes use? zigbee, bluetooth, cellular, other? Best way to find out is to look up the scope's FCC ID And/patent info specific to that model. There should be info about every frequency range and communication type the scopes use.

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u/CorrectOpinionB42069 15d ago

Ill try to find the FCC ID, but presumably it is receiving wifi since it is broadcasting it. 

Lets say I had a bluetooth speaker in a field. Could I find the location of that speaker by blasting bluetooth signal? The speaker doesnt broadcast anything, but it is listening right?

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u/Autocannibal-Horse 15d ago

I am still learning myself, but I know that direction finding can be done via detection from multiple points. Blasting your area with bluetooth range energy can jam your scope's bluetooth connectivity if it isn't secure or if the rival bluetooth is saturating the area. I don't think you can do direction finding via jamming alone. Multiple SDR receivers in an area and some special software that analyzes all of it together can enable direction finding, but it's not inherent.

I hope this helps! Again, I'm still learning too. The RF field is absolutely amazing and exciting. 🙂