WIRED has discovered a device capable of blocking phone signals that may have been deployed during the 2024 Democratic National Convention (DNC) in Chicago, raising important questions about who has authorized the use of this device and for what purpose.
The device, known as a cell emulator, was identified by the Electronic Frontier Foundation (EFF), a digital rights advocacy organization, after analyzing wireless signal data collected by WIRED in the August event.
Cell site emulators mimic cell towers to intercept communications, indiscriminately collecting sensitive data such as call metadata, location information, and application traffic from all phones within their coverage area. Their use has drawn widespread criticism from privacy advocates and activists, who say such technology could be exploited to secretly monitor protesters and herds. oppress dissidents.
The DNC was convened amid widespread protests over Israel's attack on Gaza. While Certified influencers attended exclusive yacht parties and VIP eventsthousands of protesters faced one heavy law enforcement presenceincluding officers from the U.S. Capitol Police, Secret Service, Homeland Security Investigations, local sheriff's offices and Chicago police.
Concerns about surveillance capabilities prompted WIRED to come forward the first wireless survey to investigate whether a mobile station emulator is being deployed. The reporters were armed with two rooted Android phones and Wi-Fi hotspots running usage detection software ray hunter—a tool developed by EFF to detect unusual data related to these devices. WIRED reporters monitored signals at protests and event venues across Chicago, collecting extensive data during the political convention.
Initial tests conducted during the DNC showed no conclusive evidence of cell site simulation activity. However, months later, EFF technologists reanalyzed the raw data using improved detection methods. According to Cooper Quintin, 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 technologists applied a new heuristic to test situations in which cell towers request IMSI (international mobile subscriber identity) numbers from devices. bag. According to EFF's analysis, on August 18—the day before the convention officially began—a device was carried by WIRED reporters on their way to the hotel housing Democratic Party delegates from the states. in the US Midwest suddenly switched to a new tower. That tower requests the device's IMSI and then immediately disconnects—a sequence consistent with the behavior of a cell station emulator.
“This is extremely suspicious behavior that normal towers do not exhibit,” Quintin said. He noted that EFF typically only observes similar patterns in simulated and controlled attacks. “This is not a 100% indisputable fact, but it is compelling evidence that a cell site emulator was deployed. We don't know who is responsible – it could be the US government, foreign organizations or another entity.”
Under Illinois law, law enforcement agencies must obtain permission to deploy mobile station simulators. Similarly, federal agents—including those from the Department of Homeland Security—are required to secure arrest warrants unless an immediate national security threat exists. However, the 2023 DHS Inspector General report found that both the Secret Service and Homeland Security Investigations did not always comply with these requirements.