As thousands of people took to the streets during August’s Democratic National Convention in Chicago to protest Israel’s deadly assault on Gaza, a massive security operation was already underway. U.S. Capitol Police, the Secret Service, the Department of Homeland Security’s Homeland Security Investigations, sheriff’s deputies from nearby counties, and local law enforcement from around the country had descended on Chicago and They all came out en masseworking to control crowds and ensure the event went ahead without major disruption.
Amidst the headlines and the Mostly peaceful protestsWIRED was looking for something less visible. We were investigating reports about base station simulators (CSS), also known as IMSI catchers or Stingrays, the name of one of the technology’s first devices, developed by Harris Corporation. These controversial surveillance tools mimic cell towers to trick phones into connecting to them. Activists have long worried that the devices, which can capture sensitive data such as location, call metadata, and app traffic, could be used against political activists and protesters.
Armed with a fanny pack filled with two rooted Android phones and three Wi-Fi hotspots running CSS-detection software developed by the Electronic Frontier Foundation, a digital rights nonprofit, we conducted a first-of-its-kind wireless survey of the signals around the DNC.
WIRED attended protests across the city, events at the United Center (where the Democratic National Convention was held), and social gatherings with lobbyists, political figures, and influencers. We spent time walking the perimeter along the march routes and at planned protest sites before, during, and after these events.
In the process, we captured Bluetooth, Wi-Fi, and cellular signals. We then analyzed those signals for specific hardware identifiers and other suspicious signals that might indicate the presence of a cell-station simulator. Ultimately, we found no evidence that cell-station simulators had been deployed at the DNC. When taken together, however, the hundreds of thousands of data points we accumulated in Chicago reveal how invisible signals from our devices can create vulnerabilities for activists, police officers, and everyone in between. Our investigation revealed signals from as many as 297,337 devices, including as many as 2,568 associated with a major police body camera manufacturer, five associated with a law enforcement drone manufacturer, and a huge array of consumer electronics like cameras, earbuds, Internet of Things devices, and headsets.
WIRED often observed the same devices appearing in different locations, revealing the movement patterns of their operators. For example, a Chevrolet Wi-Fi hotspot, initially located in the United Center’s law enforcement-only parking lot, was later found parked on a side street next to a demonstration in downtown Chicago. A Wi-Fi signal from a Skydio police drone flying over a large anti-war protest was detected again the next day over the Israeli consulate. And Axon police body cameras with identical hardware identifiers were spotted at multiple protests that occurred days apart.
“Surveillance technologies leave traces that can be discovered in real time,” says Cooper Quintin, a senior staff technologist at the EFF. Regardless of the specific technologies WIRED detected, Quintin notes that the ability to identify police technology in real time is significant. “A lot of our devices are emitting signals that allow us to be tracked via wireless signals,” he says. While this allows police to be tracked, Quintin says, “this makes protesters equally vulnerable to the same kinds of attacks.”
The signals we collected are a byproduct of our extremely interconnected world and demonstrate a pervasive and disturbing reality: military, law enforcement, and consumer devices constantly emit signals that can be intercepted and tracked by anyone with the right tools. In the context of high-risk scenarios such as election rallies, meetings of politicians and other high-profile officials, and large-scale protests, the findings have implications for law enforcement and protesters alike.
