Secret Cell Phone Surveillance Technology Will Likely Be Implemented at the 2024 DNC

A device capable of intercepting cellphone signals was likely deployed during the 2024 Democratic National Convention (DNC) in Chicago, WIRED has learned, raising critical questions about who authorized its use and for what purpose.

The device, known as a cell site simulator, was identified by the Electronic Frontier Foundation (EFF), a digital rights advocacy organization, after analyzing wireless signal data collected by WIRED during the event. of August

Cell site simulators mimic cell towers to intercept communications, indiscriminately collecting sensitive data such as call metadata, location information, and app traffic from all phones in their range. Its use has drawn widespread criticism from privacy advocates and activists, who argue that such technology can be exploited to secretly monitor protesters and suppress dissent.

The DNC met amid widespread protests over Israel’s assault on Gaza. While credentialed influencers attended exclusive yacht parties and VIP eventsthousands of protesters faced a strong law enforcement presenceincluding officers from the United States Capitol Police, the Secret Service, Homeland Security Investigations, local sheriff’s offices and the Chicago Police Department.

Concerns about potential surveillance prompted WIRED to conduct a first-of-its-kind wireless survey to investigate whether cell site simulators have been implemented. Reporters, equipped with two rooted Android phones and Wi-Fi hotspots running detection software, used Rayhunter-a tool developed by the EFF to detect data anomalies associated with these devices. WIRED reporters monitored signs at rallies and event venues in Chicago, collecting extensive data during the political convention.

Initial tests conducted during the DNC revealed no conclusive evidence of cell site simulator activity. However, months later, EFF technologists reanalyzed the raw data using improved detection methods. According to Cooper Quintin, a senior technologist at the EFF, the Rayhunter tool stores all interactions between devices and cell towers, allowing for deeper analysis as detection techniques evolve.

A breakthrough came when EFF technologists applied a new heuristic to examine situations where cell towers requested IMSI (international mobile subscriber identity) numbers from devices. According to EFF’s analysis, on August 18 – the day before the official start of the convention – a device carried by WIRED reporters en route to a hotel hosting Democratic delegates from states in the Midwest of the United States suddenly changed to a new tower. This tower requested the IMSI of the device and then immediately disconnected-a sequence consistent with the operation of a cell site simulator.

“This is extremely suspicious behavior that normal towers don’t show,” says Quintin. He notes that the EFF typically observes similar patterns only during simulated and controlled attacks. “This is not 100 percent incontrovertible truth, but it is strong evidence that suggests that a cell site simulator was implemented. We do not know who was responsible – it could be the United States government, foreign actors, or another entity.”

Under Illinois law, law enforcement agencies must obtain a warrant to deploy cell site simulators. Similarly, federal agents—including those of the Department of Homeland Security—are required to secure warrants unless an immediate threat to national security exists. However, a 2023 DHS Inspector General report found that both the Secret Service and Homeland Security Investigations did not always comply with these requirements.