Yvon FeasterCody GentryMatt RardonCPSC 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 24th satellite launched in 1993

Each GPS receiver must know:1. Where the satellites are2. How to accurately calculate time3. 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.(http://www.standardchartered.com/online-banking/security-tips/glossary/en/#q30)

Def: Spoofing refers to the process of replicating the GPS code so that the user computes incorrect position solutions.

(http://www.modularmining.com/gps/glossary.htm)

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 Steps1. Release receiver’s lock on GPS constellation2. Force receiver lock on spoofing satellite3. 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. 2008.MSNBC.28 Nov. 2008 <gps 'spoofing' could threaten national security>.

Cornell Chronicle Online - http://www.news.cornell.edu/stories/Sept08/GPSSpoofing.aj.html

Diaz, Jesus. "Windows 7's New Geolocation Service Introduces Privacy Problems." Gizmodo. 10 Nov. 2008. 28 Nov. 2008 <http://gizmodo.com/5082276/windows-7s-new-geolocation-service-introduces-privacy-problems>.

Discovery.com GPS “Spoofing” Could Threaten National Security http://dsc.discovery.com/news/2008/10/02/gps-spoofing.html

History of GPS (http://usinfo.state.gov/xarchives/display.html?p=washfileenglish&

y=2006&m=February&x=20060203125928lcnirellep0.5061609) ", usinfo.state.gov(http://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. 2008. Institution of Navigation. 28 Nov. 2008 <http://www.ion.org/meetings/gnss2008/abstracts.cfm?track=c&session=5>.

Ju, Anne. "Spoofing GPS Receivers." Cornell Chronicle. 19 Sept. 2008.Cornell University.28 Nov. 2008 <http://www.news.cornell.edu/stories/sept08/gpsspoofing.aj.html>.

National Academy of Science, 2003 GPS_ The Role of Atomic Clocks – Text View.pdf http://www.beyonddiscovery.org/content/view.txt.asp?a=458 

RMBL – How GPS Actually Works.pdf http://thermbl.googlepages.com/howgpsactuallyworks

Scott, Logan. "Expert Advice -- Location Assurance." GPS World. 01 July 2007. 28 Nov. 2008 <http://sidt.gpsworld.com/gpssidt/content/printcontentpopup.jsp?id=436920>.

Sherri. "GPS Spoofing." Philosecurity. 7 Sept. 2008. 28 Nov. 2008 <http://philosecurity.org/2008/09/07/gps-spoofing>.

Uses for GPS.pdf  Warner, Jon S., Ph.D. and Johnston, Roger G., Ph.D., CPP, GPS

Spoofing Countermeasures: 2003 http://www.homelandsecurity.org/bulletin/Dual%20Benefit/warner_gps_spoofing.html