Spectrum Analyzer is the best choice but there are phone applications that can do this job, relatively accurate.
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My main focus is to analyse what kind of “UNWANTED” wireless signals are emitted from various “rogue” and “compromised” devices. Primarily when someone is a “target” for unauthorized data exfiltration (high profile hacking), I noticed that even air gapped systems (like laptops, notebooks, mobiles, tablets etc with every wireless card and lan adapter physically removed) are able to emit radio/gsm or other forms of signals to capture and transmit audio and video data to and from nearest wifi router/device along with giving full access to compromised machine itself by the hacker in real time. Which means the hacker virtually has full control over the system in real time, the moment victim opens the lid and push the power on button.
Which in conclusion means that, whatever one does even in an “air gapped” machine (with every wireless internal/external card or lan wire physically removed), can also be recorded and have access to by the hackers in real time. This is usually achieved when the compromised air gapped machine has some sort of hidden malware “deceptive” transceiver chip planted inside the motherboard (or main cpu processor itself) that constantly sends/receive data in real time virtually giving carte-blanch access to the victim’s machine by the hackers even in an air gapped state.
In such a scenario, it becomes extremely risky if the victim plans to venture into projects like developing his/her own movie scripts, 3d plans, or prepare for litigation against powerful agencies. As whatever he/she does even in his air gapped machine will eventually be leaked and ends up in the hands of the adversaries, nullifying all of his efforts, hard work and creativity.
What I feel the best can be done in such a scenario is to either switch to paper/pen based model. Or rely on a system (Counter Surveillance Device) that can detect the presence of such rogue signals so that the particular device in question can either be rectified or be discarded.
After doing lots of research, I came across couple of such devices (however both of them are way too expensive in terms of cost affordability). Following :
[ DeltaX G2 - Countersurveillance sweeping system ]
[ ANDRE® Deluxe Near-field Detection Receiver ]
They both seem to be out of reach from a common man’s pocket. However, with proper knowledge, guidance and information I am confident that one can shortlist a suitable spectrum analyzer that can do the similar detection job without hurting too much on the pocket. Would appreciate any advice. Thanks.