Secret Phone Monitoring Tech Should Be Deployed to 2024 DNC

A device capable of jamming phone signals may have been used at the 2024 Democratic National Convention (DNC) in Chicago, WIRED has learned, raising serious questions about who authorized its use and what it was for.

The device, known as a cell-site simulator, was discovered by the Electronic Frontier Foundation (EFF), a digital liberties organization, after analyzing wireless data collected by WIRED during the August incident.

Mobile trackers impersonate platforms for communication, indiscriminately collecting sensitive data such as call metadata, location information, and app traffic from all phones in their domain. Their use has drawn criticism from privacy advocates and rights activists, who say such technology can be used to surreptitiously monitor and suppress dissent.

The DNC met amid protests over Israel’s actions in Gaza. When celebrities attended exclusive yacht parties and VIP eventsthousands of demonstrators faced a the presence of law enforcement officersincluding the US Capitol Police, Secret Service, Homeland Security Investigations, local sheriff’s offices, and the Chicago Police Department.

Concerns about the potential for censorship prompted WIRED to act a first-of-its-kind wireless study to investigate whether cell site simulators are being deployed. Journalists, with two rooted Android phones and Wi-Fi hotspots running detection software, used Rayhunter-a tool developed by EFF to identify data errors associated with these tools. WIRED reporters covered demonstrations at protests and event centers in Chicago, gathering information on the political rally.

Preliminary tests conducted in the DNC showed no conclusive evidence of cell-site simulator activity. However, a few months later, EFF’s technical experts re-analyzed the incident using more sophisticated methods. According to Cooper Quintin, chief technology officer at EFF, the Rayhunter tool keeps track of all interactions between devices and cellular platforms, allowing for deep analysis of how detection methods are changing.

The breakthrough came when EFF engineers used a new method to detect when cell platforms requested IMSI (international mobile subscriber identity) numbers for devices. According to EFF’s analysis, on August 18, one day before the start of the meeting, the device carried by WIRED reporters on the way to the hotel where the Democratic delegates from the US Midwest states suddenly changed to a new building. The tower requested the device’s IMSI and immediately disabled it—a list that matches the operating system’s operating system.

“These are very suspicious things that normal platforms don’t show,” says Quintin. He added that the EFF often observes similar processes during the trial and correction process. “This is not an undisputed fact, but it is strong evidence that the cell test machine was sent. We do not know who was responsible, whether it was the United States government, foreign agencies or other organizations.”

Under Illinois law, law enforcement agencies are required to obtain a subpoena to transmit stem cell tests. Similarly, government agencies – including those from the Department of Homeland Security – must obtain authorizations only when a national security threat exists. However, 2023 DHS Inspector General report found that the Secret Service and Homeland Security Investigations did not cooperate.