By triangulating location information from different cell phone towers, cell phone providers can geolocate phones more accurately. This is often done to direct emergency services to a particular person, such as someone who has made a 911 call. The NSA can get this data either by network eavesdropping with the cooperation of the carrier, or by intercepting communications between the cell phones and the towers. A previously released a Top Secret NSA document says this: “GSM Cell Towers can be used as a physical-geolocation point in relation to a GSM handset of interest.”

This technique becomes even more powerful if you can employ a drone. Greenwald and Scahill write:

The agency also equips drones and other aircraft with devices known as “virtual base-tower transceivers”—creating, in effect, a fake cell phone tower that can force a targeted person’s device to lock onto the NSA’s receiver without their knowledge.

The drone can do this multiple times as it flies around the area, measuring the signal strength—and inferring distance—each time. Again from the Intercept article:

The NSA geolocation system used by JSOC is known by the code name GILGAMESH. Under the program, a specially constructed device is attached to the drone. As the drone circles, the device locates the SIM card or handset that the military believes is used by the target.

The Top Secret source document associated with the Intercept story says:

As part of the GILGAMESH (PREDATOR-based active geolocation) effort, this team used some advanced mathematics to develop a new geolocation algorithm intended for operational use on unmanned aerial vehicle (UAV) flights.

This is at least part of that advanced mathematics.

None of this works if the target turns his phone off or exchanges SMS cards often with his colleagues, which Greenwald and Scahill write is routine. It won’t work in much of Yemen, which isn’t on any cell phone network. Because of this, the NSA also tracks people based on their actions on the Internet.

Finding You From Your Web Connection

A surprisingly large number of Internet applications leak location data. Applications on your smart phone can transmit location data from your GPS receiver over the Internet. We already know that the NSA collects this data to determine location. Also, many applications transmit the IP address of the network the computer is connected to. If the NSA has a database of IP addresses and locations, it can use that to locate users.

According to a previously released Top Secret NSA document, that program is code named HAPPYFOOT: “The HAPPYFOOT analytic aggregated leaked location-based service / location-aware application data to infer IP geo-locations.”

Another way to get this data is to collect it from the geographical area you’re interested in. Greenwald and Scahill talk about exactly this:

In addition to the GILGAMESH system used by JSOC, the CIA uses a similar NSA platform known as SHENANIGANS. The operation—previously undisclosed—utilizes a pod on aircraft that vacuums up massive amounts of data from any wireless routers, computers, smart phones or other electronic devices that are within range.

And again from an NSA document associated with the FirstLook story: “Our mission (VICTORYDANCE) mapped the Wi-Fi fingerprint of nearly every major town in Yemen.” In the hacker world, this is known as war-driving, and has even been demonstrated from drones.