Covert phone monitoring technology will likely be deployed at the 2024 DNC

A device capable of intercepting phone signals may have been 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 August event.

Cell site simulators mimic cell towers to intercept communications, and randomly collect sensitive data such as call metadata, location information, and application traffic from all phones within range. Its use has drawn widespread criticism from privacy advocates and activists, who claim the technology could be exploited to secretly monitor protesters and suppress dissent.

The Democratic National Convention was held amid widespread protests over the Israeli attack on Gaza. while Certified influencers attended exclusive yacht parties and VIP eventsThousands of demonstrators faced a Heavy presence of law enforcement forcesincluding officers from the U.S. Capitol Police, Secret Service, Homeland Security Investigations, local sheriff’s offices, and Chicago Police.

Concerns about potential surveillance prompted WIRED to do so A first-of-its-kind wireless survey was conducted to check whether cell site simulators are being deployed. Messengers were used, equipped with Android phones and detection-enabled Wi-Fi hotspots Rayhunter– A tool developed by EFF to detect anomalies in the data associated with these devices. WIRED reporters monitored signals at protests and event sites throughout Chicago, and collected extensive data during the political convention.

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

The breakthrough occurred when EFF technologists implemented a new heuristic to examine situations where cell towers request IMSI (International Mobile Subscriber Identity) numbers from devices. According to an analysis by the Electronic Front Foundation, on August 18 — one day before the convention officially began — a device carried by WIRED reporters on their way to a hotel housing Democratic delegates from states in the US Midwest suddenly turned into a new tower. This tower dialed the device’s IMSI number and then immediately lost contact, a sequence consistent with the operation of a cell site simulator.

“This is very suspicious behavior that normal zodiac signs don’t exhibit,” Quentin says. He points out that the EFF typically only noticed similar patterns during simulated and controlled attacks. “This is not a 100% indisputable fact, but it is strong evidence that a cell site simulator was deployed. We do not know who is responsible, it could have been the US government, foreign actors, or another entity.”

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