Back in April of 2018, DHS warned of many illegal devices (Original Story) in which some were legitimate law enforcement use and others that were being used illegally by threat actors. Part of the issue with the increased use of Stingray devices is the fact that there is no coordination between law enforcement, intelligence agencies or private companies that are authorized to utilize the technology on contract to other agencies. This lack of coordination creates scenarios where many IMSI catchers and fake mini towers are in operation in the same locations.
In locations where people frequently travel such as train stations, airports and ports of entry, we observe high numbers of fake cellular towers. The same issue is also playing out near embassies, military bases and other locations. The main problem is that over the past 10 years, the technology to allow this type of activity moved from expensive hardware that was out of the reach of threat actors to software defined radios that can emulate literally any type of communications device on the planet with simple software configurations that allow snooping, tracking and other nefarious activity.
As has been previously reported, many foreign embassies are also active in this area. Simply walking near embassies and monitoring the tower ID and information on your phone will be an enlightening experience. We observed our tower ID changing 4 times in 1 block and another 6 times the next block indicating that the problem is widespread. A review of cellular tower data from the FCC and other sites allowed us to know that in the location we were working, there should have only been 3 towers active (different carriers) and we noted 13 active and other strange activity such as our LTE service dropping to 2G which is an indication of a positive operation because 2G allows attacks to be carried out that are not possible with newer networks due to the methods in which phones authenticate to the cellular network.
Previously we noted some locations were we have been testing and we have had the cooperation of a nationwide carrier that has allowed us to map out network activity over most of the US, the problem is not just in big cities and around Government installations. In fact we noted activity in nearly all states where we have collected data. Another problem is passive listening as you can track users without even knowing who they are initially, after time you can use the locations to narrow down to individual users without even tipping them off that you are listening. As technology improves, it's easier to manipulate cellular devices and the barrier to entry gets lower as new hardware becomes available. New software defined radios are allowing inexpensive tinkering by anyone with time to research, compile some software and purchase of hardware that cost less than most peoples dinners.
In short, protect yourselves. This widespread problem is getting worse a year later, not better!