Secret phone surveillance technology likely deployed at 2024 DNC

A device capable of intercepting phone 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 during the August event.

Cell-site simulators simulate cell towers to intercept communications, arbitrarily collecting sensitive data such as call metadata, location information, and app traffic from all phones within their range. Their use has drawn widespread criticism from privacy advocates and activists, who argue that such technology can be used to covertly monitor protesters and suppress dissent.

The DNC called amid widespread protests against Israel’s attacks on Gaza. when Certified influencers attended exclusive yacht parties and VIP eventsFacing thousands of protesters Heavy law enforcement presenceincluding officers from the US Capitol Police, Secret Service, Homeland Security Investigations, local sheriff’s offices, and the Chicago Police Department.

Concerns about potential surveillance prompted Wired to operate A first-of-its-kind wireless survey to investigate the deployment of cell-site simulators. Reporters, equipped with two rooted Android phones and Wi-Fi hotspot running detection software, were used Rayhunter—A tool developed by EFF to detect data anomalies associated with these devices. WIRED’s reporters monitored signals at protest and event locations across Chicago, gathering extensive data during political conventions.

Preliminary tests during the DNC found no conclusive evidence of cell-site simulator activity. However, months later, EFF technicians reanalyzed the raw data using advanced detection methods. According to Cooper Quintin, a senior technologist at 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 technicians applied a new heuristic to test for situations where cell towers requested IMSI (International Mobile Subscriber Identity) numbers from devices. According to EFF’s analysis, on Aug. 18—the day before the official launch—a device carried by Wired reporters on its way to a hotel housing Democratic delegates from US Midwest states suddenly moved to a new tower. That tower asked for the device’s IMSI and then promptly disconnected—a sequence consistent with the operation of a cell-site simulator.

“This is highly suspicious behavior that normal towers do not exhibit,” Quintin said. He noted that the EFF typically observes similar patterns only during simulated and controlled attacks. “It’s not 100 percent overwhelmingly true, but it’s strong evidence to suggest that a cell-site simulator was deployed. We don’t know who was responsible — it could be the U.S. government, foreign actors or some other entity.”

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