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Controversial cellphone tracking technology is being deployed as a tool in President Donald Trump’s expanding effort to arrest and deport illegal US residents.

In March, US Immigrations and Customs Enforcement (ICE) deployed a cell-site simulator, often colloquially referred to as a “Stingray,” to track a Michigan man in the country illegally, according to recently unsealed court documents reported first by The Detroit News.


The local news outlet reported Thursday evening that a team of FBI and ICE agents in Detroit used a cell-site simulator to locate Rudy Carcamo-Carranza, a restaurant worker from El Salvador who had twice entered the country illegally. The 23-year-old reportedly accused of driving drunk and being involved in a hit-and-run crash.

This represents the first known case of such a device being used to hunt down an undocumented immigrant. Nathan Wessler, a staff attorney at the American Civil Liberties Union and widely recognized expert on cell-site simulator use, told the Michigan paper that he had never before seen a warrant approved in an immigration enforcement operation.

The use of cell-site simulators is a closely guarded secret among US law enforcement, typically bound by a nondisclosure agreement between agencies, the FBI, and the Harris Corporation, a US-based company which produces the Hailstorm, a slightly more advanced version of the more widely known Stingray model.

The Hailstorm, which is roughly the size of a suitcase, operates by emulating base transceiver stations, or “cell towers.” By transmitting a radio signal slightly more powerful than those of legitimate local towers, the Hailstorm forces nearby cellphones to drop connection to legitimate networks—those operated by AT&T, Verizon, and other providers—and re-connect to the police device instead. This works by exploiting the fact that cellphones are designed to always seek out the most powerful nearby signal to reserve battery power. The process is a little more complex, however.


The Harris device doesn’t just passively collect information from nearby cellphones by simply pretending to be something it’s not. With regard to modern LTE networks, on which most cellphones in the US now operate, a more apt description for the Hailstorm is a “cellular hacking device.” Older GSM networks only require cellphones to authenticate one way: the cellphone must prove it is authorized to be on the network, but the tower is not required to respond in kind. LTE, however, uses a more secure protocol called “two-way authentication.”

Essentially, this means that Hailstorms can only fool an LTE phone by authenticating itself back to the device, perfectly emulating a complex, multi-step “handshake” protocol with fraudulent credentials. (A hack by any other name is still a hack.)


The use of this device under any circumstance poses a unique threat to bystanders. Cell-site simulators are known by their very nature to disrupt calls—even ones to 911. A 2014 case in Canada noted that cell-site simulators pose inherent risks to “innocent third parties,” particularly those trying to reach emergency services. Canadian authorities instituted a three-minute rule with regard to their use after tests revealed frequent malfunctions in software designed to allow emergency calls to go through. No such limitations have been imposed in the US, however.

Because coverage blackouts are a byproduct of using cell-site simulators they’ve often been compared to cellphone jammers, the use of which constitutes a federal crime.


The Federal Communications Commission defines a cellphone jammer as a device that prevents cellphones from “making or receiving calls, text messages, and emails,” and further notes that jammers do not “discriminate between desirable and undesirable communications.” While that definition appears to fit the bill, and federal law prohibits police from using cellphone jammers under any circumstance, the FBI and other federal agencies routinely provide state and local police with access to cell-site simulator technology. Other agencies, including the U.S. Secret Service, are known to share their devices with local agencies.

Law enforcement operations to locate, detain, and deport individuals in the US illegally are skyrocketing. Figures released this week by Acting ICE Director Tom Homan show a nearly 40 percent uptick in detentions during President Trump’s first 100 days in office. As many as 41,300 undocumented immigrants have been arrested, and of those, nearly 11,000 had no prior criminal convictions—that’s double the number arrested over the same period last year.


While Homeland Security requires ICE and other agencies under its umbrella to obtain warrants before deploying cell-site simulators, should their use become typical, the result may be increased network issues for law abiding citizens. Due to the secrecy surrounding use of these devices, it will be well-nigh impossible to attribute any such disruption to ICE’s enforcement operations.

In a statement to The Detroit News yesterday, an ICE spokesman Khaalid Walls defended the agency’s use of cell-site simulators: “ICE officers and special agents use a broad range of lawful investigative techniques in the apprehension of criminal suspects,” he said. “Cell-site simulators are invaluable law enforcement tools that locate or identify mobile devices during active criminal investigations.”


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