How can we find out whether the Department of Homeland Security spy plane spotted on the tarmac at PDX is equipped with surveillance electronics to spy on Black Lives Matter protesters? Is DHS assembling a list of "terrorists" for future targets? —Inga W.

Come, come, Inga; you can't just say "DHS spy plane" and expect me to know what you're talking about. Do you mean the Cessna Caravan that circled downtown Portland for three hours on June 13? Or one of the two Beechcraft Super King Air 350s that did the same on July 22, 28, and 29?

Then again, maybe you mean the U.S. Air Force Dornier 328 surveillance plane than made five flights over Portland from July 21 to 23. Or perhaps you're talking about the Lockheed P-3 AWACS plane (as seen in Iraq Wars I and II!) that turned up at PDX on July 23?

In any case, as reported in WW on Aug. 5, the flight patterns of at least the first three planes above are consistent with an electronic surveillance technology called "dirtboxing."

A dirtbox is a high-tech wireless transmitter, sometimes mounted in a small plane, that pretends to be a cellphone tower. When your phone (and every other phone in the vicinity) tries to connect to this fake tower, the box collects its electronic serial number, its approximate location, and the time and duration of calls it makes. It can do this even if you're using a cellphone privacy app like Signal that encrypts your calls and texts. If you're not, it may get those as well.

Sure, the authorities might need a subpoena to connect that raw cell data to a name and address, but it doesn't matter. Say an ESN harvested at a Portland protest on June 29 turns up at a protest in Chicago on Sept. 5. That's suspicious enough to get that subpoena, no problem. Nice try, Osama!

Or, if they're in a hurry, they can just use the proximity-tracking function on a second dirtbox—in an unmarked van, say—to hunt your terrorist ass down in person.

The whole thing is extremely creepy, and it's probably only the staggering incompetence of the Trump administration that's keeping it from being even worse. In the meantime, protesters might consider picking up a cheap burner—or even, God forbid, leaving the phone at home.

Questions? Send them to dr.know@wweek.com.