https://www.theverge.com/2018/6/3/17422248/imsi-catcher-stingray-dhs-cell-phone-spying-washington-dc-white-house-donald-trump

Last year, the Department of Homeland Security launched a pilot project in Washington DC, deploying a network of sensors to ascertain the extent of cell phone surveillance being conducted in the capitol. They found that not only were International Mobile Subscriber Identity (IMSI) catchers in use, but some were being used in proximity to “potentially sensitive facilities like the White House.”

The revelation comes from a letter sent to Senator Ron Wyden of Oregon, a member of the Select Committee on Intelligence from Christopher C. Krebs, the Senior Official Performing the Duties of the Undersecretary for National Protection and Programs Directorate (NPPD), who was recently nominated to become the directorate’s Undersecretary. In his letter, Krebs notes that the test was to “better understand potential IMSI catcher activity” in the region, and that while the NPPD observed activity near the White House, it didn’t validate or attribute the activity to any “specific entities, devices, or purposes.” Some of this activity could have been from legitimate sources: he notes that US counterintelligence and law enforcement personnel followed up and “determined some detected signals were emanated from legitimate cell towers.” But this leaves the possibility that some of these signals were not from US authorities.