Yvon Feaster Cody Gentry Matt Rardon CPSC 420

 History of Global Positioning System (GPS)  We will define spoofing and the different types.  Why would someone want to spoof a GPS?  Recent research on spoofing.  Countermeasures.

 We all know what GPS is and have used it directly or indirectly  How it works may be another story

 GPS we use today is based off of earlier technologies  Sputnik’s launch (1957)  Scientists use the Doppler Effect to measure distance of its orbit  Launch of Navy’s Transit System (1965)  Used to guide Polaris missiles for submarines  Launch of first NAVSTAR-GPS (1978)  What we use today  24 th satellite launched in 1993

 Each GPS receiver must know: 1. Where the satellites are 2. How to accurately calculate time 3. The speed of the radio signal from the satellite

 Triangulation is used  Uses at least 4 satellites to ensure accuracy  Measured by the intersection of each satellite’s signal-intercept radius  A random signal is generated and repeated by both the satellite and receiver  The lag time, or time it takes for the receiver to receive the signal travelling from the satellite, is used to calculate distance from the satellite

 Police use it to find out the closest officer to an emergency  Rescuers use it to find exact locations of stranded people  For example: miners were lost underground – GPS used to find out where to excavate to find them.  Used in navigation of airplanes, cars, etc.  Scientist use it for its accurate and precise timing  Timing to the billionth of a second  Location up to 3 – 6 mm on the most accurate units

 Spoofing  Def: a generic term covering a range of computer network attacks whereby the attacker attempts to forge or intercede in a chain of communication. (  Def: Spoofing refers to the process of replicating the GPS code so that the user computes incorrect position solutions. (

 Monetary Gain  Fishermen  Waste Disposal  Terrorism  Power Generators  Air Traffic Controllers  Privacy Concerns  Windows 7

 Software Code Spoofing  Differential Corrections Spoofing  GPS Signal Constellation Spoofing

 Cornell / Virginia Tech

 Argonne National Laboratories VAT  3 Steps 1. Release receiver’s lock on GPS constellation 2. Force receiver lock on spoofing satellite 3. Continue broadcasting spoofing signal  Can be achieved from 4586 ft away without direct LOS.

 Monitor the absolute GPS signal strength  Monitor and record the average signal strength  Compare the observed signal strength to the expected signal strength. If the absolute value of the observed signal exceed what is expected the receiver alerts the user  This is an unambiguous indication of a spoofing attack  This countermeasure takes minimal software changes

 Monitor the relative GPS signal strength  Modify the receiver software to record and compare the average signal strength from one moment to the next.  An extremely large change in the relative signal strength would indicate the beginning of a counterfeit GPS signal overriding the true satelite signal.  If the signal increases beyond a preset point then the end user is notified.

 Monitor the strength of each received satellite signal  This countermeasure is an extension of the first two countermeasures.  The relative and absolute signals strengths are monitored for each incoming satellite.  The signal coming from the artificial satellite tend to be of equal strength. Real satellite signal strengths vary and change over time. Therefore, if the signal strengths are too perfect this is an indication that the

 Monitor Satellite identification codes and the number of satellite signals received  GPS satellite simulators transmit signals from multiple satellites (usually 10) which is more than the number of real signals detected by a GPS receiver in the field. Keeping track of both the number of satellite signals received and the satellite identification codes over time will help determine foul play.

 Check the time Intervals  With most GPS satellite simulators, the time between the artificial signal from each satellite and the next is constant.  Real satellite receivers will pick up a signal from one satellite and a few moments later pick up another.  With satellite simulators the receiver picks up signals from all of the satellites simultaneously.  This will alert the user that there is a problem.

 Do a time comparison  Many current GPS receivers do not have an accurate clock.  By using timing data from an accurate, continuously running clock to compare with the time derived from the GPS signal, we can check the validity of the received GPS signal.

 Perform a sanity check  A small, solid-state accelerometer and compass can be used to independently monitor the physical trajectory of the receiver.  The information provided by this approach can be used to check the current position reported by the GPS based on the previously reported position.

 We covered the history of GPS  We defined spoofing and talked about different types of spoofing  We gave you examples of why a GPS might be spoofed  We talked about current research on spoofing GPS  Lastly, we talked about ways to combat spoofing.

 Bland, Eric. "GPS 'spoofing' could threaten national security." 02 Oct MSNBC.28 Nov  Cornell Chronicle Online -  Diaz, Jesus. "Windows 7's New Geolocation Service Introduces Privacy Problems." Gizmodo. 10 Nov Nov  Discovery.com GPS “Spoofing” Could Threaten National Security  History of GPS (  y=2006&m=February&x= lcnirellep ) ", usinfo.state.gov( (February 3, 2006).  Humphreys, T.E., B.M. Ledvina, M.L. Psiaki, and P.M. Kitner, Jr. "Assessing the Spoofing Threat: Development of a Portable GPS Civilian Spoofer." Sept Institution of Navigation. 28 Nov

 Ju, Anne. "Spoofing GPS Receivers." Cornell Chronicle. 19 Sept Cornell University.28 Nov  National Academy of Science, 2003 GPS_ The Role of Atomic Clocks – Text View.pdf  RMBL – How GPS Actually Works.pdf  Scott, Logan. "Expert Advice -- Location Assurance." GPS World. 01 July Nov  Sherri. "GPS Spoofing." Philosecurity. 7 Sept Nov  Uses for GPS.pdf  Warner, Jon S., Ph.D. and Johnston, Roger G., Ph.D., CPP, GPS Spoofing Countermeasures: poofing.html