Stingray Makes Waves

min read

Or, How Technology Helps Your Friendly Neighborhood Policeman Violate Your Privacy in New and Innovative Ways

Geoffrey S. Nathan, Faculty Liaison for Computing and Information Technology, Wayne State University

We already know that our government (and other people's governments) like to collect vast amounts of data on its citizens, on the off-chance that the data might prove useful in preventing a terrorist attack. And, given the extent of mission creep, that data is also being used in other kinds of criminal investigations, such as drug investigations and child pornography prosecutions (although perhaps not always in a legitimate manner). [1] That data is collected at a national level, however, and has not (to the best of public knowledge) been shared with local law enforcement.

However, it turns out that a tool developed for the purpose of fighting terrorism by snooping on cellphone usage has now been made available to local police and is being used, in a surprisingly large number of cases.

The tool, known as Stingray, is made by the Harris Corporation []. It's about the size of a small suitcase and functions as a cellphone tower. When turned on it forces all cellphones within range to connect to it and can then extract certain kinds of data from the phones it connects to (which is all the phones within normal cellphone range). The data includes the International Mobile Subscriber Identity (IMSI, a unique number commonly associated with a phone's SIM card), Electronic Serial Number (ESN, a similar number used in CDMA phones), or other similar data — information uniquely identifying a phone. But it also can collect the encryption key and then retransmit the signal (with appropriate authentication) to a real cellphone tower, thus creating what security folks call a "man in the middle" attack. [2]

Law enforcement, knowing the phone ID data, can then identify the carrier and get the identities of the users. Suggested usage includes collecting the identities of everyone carrying a cellphone while engaging in a protest — or at least being in the general vicinity of one.

Although these devices were originally designed to be used by Homeland Security, they have been made available to state and local law enforcement agencies through the Homeland Security grants that were made somewhat notorious recently as civil libertarian attention has focused on the increased militarization of local police. They have also been purchased through civil forfeiture fund accounts, another law enforcement tool that has been, to say the least, controversial. [3]

Law enforcement agencies that have bought these devices (and used them, needless to say) include Hennepin County MN, Sunrise County FL, and several others.

The immediate question that the use of these devices raises is whether they are legal. The fourth amendment, which requires searches to be carried out through the issuance of a warrant, has not been precisely delineated for cases like these. When the government forces your cellphone to connect to its recording device, rather than to a cellphone tower (Stingray uses electronic trickery to do this), is that a search? Some courts have ruled that cellphone connection data is public, while others have ruled it is not, and the Supreme Court has not yet heard such a case.

However the issue is decided, people should know that their cellphones are potentially connected to police monitoring devices, and currently there is no oversight over when the police are doing this, especially not judicial oversight.

And, just when you thought it was safe to hide in your home, there's another piece of technology police have begun using, the Range-R. [4] It's a device that uses radar signals to detect movement through walls. [5] The police claim they're using them in advance of SWAT raids (presumably accompanied by a warrant permitting the raid), but a Supreme Court ruling in 2001 stated that the police cannot use infrared devices to do just this, so it's unlikely that the use of radar signals rather than passive reception of infrared patterns would make a legal difference.

Most disturbing of all in the use of these privacy-invading technologies is that the police have in general attempted to hide their use, claiming that they used a confidential source, or that to reveal the use of the device would violate a nondisclosure agreement with the manufacturer.

In the end, there's probably nothing you can do to protect your privacy against these devices, other than to hope that someone with a great deal of money will be willing to try to get their use brought before the Supreme Court. The hope being, of course, that the court will think this is not what the founding fathers had in mind when they objected to the politically motivated searches that King George III's men indulged in lo those many years ago.


  1. Clarence Walker, "New Hi-Tech Police Surveillance: The 'Stingray' Cell Phone Spying Device," Global Research, November 14, 2014.
  2. Kate Klonick, "Stingrays: Not Just for Feds!" Slate, Future Tense, Nov. 10, 2014.
  3. US Attorney General Holder recently moved to restrict the use of civil forfeiture, which essentially allows police to seize money and goods from people the police suspect of some crime. The money was then available for law enforcement use to purchase supplies such as tanks and Stingrays.
  4. Brad Heath, "New Police Radars Can 'See' Inside Homes," USA Today, January 20, 2015.
  5. Mariella Moon, "FBI and US Marshals Stock Up on Radars That Can See through Walls," Engadget, January 23, 2015.


© 2015 Geoffrey S. Nathan. The text of this EDUCAUSE Review blog is licensed under the Creative Commons Attribution 4.0 license.

Geoff Nathan blogs at