SeaGlass: Policing IMSI-Catchers - aka Stingray Devices

June 07, 2017 3 min read

SeaGlass:  Policing IMSI-Catchers - aka Stingray Devices


Security researchers at the University of Washington have created a system called ‘SeaGlass’ to detect cell-site simulators (aka stingray devices - aka IMSI-catchers) all across a major city in an attempt to monitor the people who are monitoring us:  government and law enforcement.


Why Did Researchers Create SeaGlass?


Even though many of us have heard of the technology known as IMSI-catchers, few of us realize just how they work and how widely used these devices have become.

Your average person may not be aware of the fact that there can be dozens of these stingray devices in use across a city at any one time and they are running 24/7.  Our smart phones, while extremely useful and convenient, are also glaring vulnerabilities when it comes to our privacy and sensitive data.

While out and about, your cell phone could be giving away your location in real-time, your texts can be read, and your conversations recorded.

The security researchers at the University of Washington wanted to develop independent monitoring in an attempt to obtain information that was previously hidden from the public.


What Is An IMSI-Catcher? 


AnIMSI-catcher, or international mobile subscriber identity-catcher, is a type of device engineered to intercept and eavesdrop on unsuspecting mobile cell phone users.

*It is important to note that IMSI-catchers are also called stingray devices or cell-site simulators, and all 3 of these terms are interchangeable.

Using a “MITM” or man-in-the-middle-attack, an IMSI-catcher disguises itself as a WiFi hotspot or even a cellular tower.  Once the victim’s phone connects to it (and they often do not require permission), the hacker(s), or police in this case, have complete access to everything on it.


How Does SeaGlass Work?


SeaGlass uses an array of sensors built from fairly ordinary parts you can find at a Radio Shack.  These sensors are then attached or installed to various vehicles that tend to drive long hours or into many parts of a city.

imsi catcher stingray device cell site simulator seaglass university washington

This array of sensors will then pick-up all the broadcast signals from the appropriate cellular network, and create an aggregate map to show what “baseline” cellular activity looks like in the city.

imsi catcher stingray device university washington cell site simulator

From this baseline data, the researchers were able to build algorithms and statistical models that would detect any abnormalities in the area.

A co-author of the study and UW’s Allen School professor Tadayoshi Kohno explained, “We’ve demonstrated that SeaGlass is effective in detecting these irregularities and narrowing the universe of things people might want to investigate further.”


SeaGlass Finds Unusual Activity


So as one might imagine, once the researchers unleashed SeaGlass onto the city, they ended up with some rather strange and/or alarming findings.

For example, the US Department of Homeland Security runs an immigration services building just South of Seattle.  SeaGlass alerted that the tower next to the buildings ran or transmitted over six different frequencies over an 8-week period.   It’s unusual because 96% of all the other baseline towers around the city only utilize a single channel.   The other 4% will only use two or three.

Another strange finding was with a possible cell-site simulator operating around the Seattle-Tacoma International Airport.   This particular “cell tower” was operating in a decisively different manner, and the researchers said more investigation would be necessary in order to draw a definitely conclusion.



Not much is known by the public regarding these stingray devices, and that’s troubling considering the amount of use they seem to be getting these days.  

Without transparency in government and law enforcement, our surveillance state will become increasingly out of control.

An inexpensive solution to provide more of this transparency, SeaGlass is serving a vital purpose for the public, and one can only hope the use of it finds its way into every major city and town in America.

If you’re worried about your smartphone leaving you vulnerable to this type of man-in-the-middle attack, your best bet and for immediate peace of mind, is to use one of our patentedFaraday Phone Sleeves.

It takes less than a second to drop it inside the sleeve, and the patented magnetic enclosure will snap shut, blocking ALL wireless signals to and from your cell phone.

Josh Bare
Josh Bare

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