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
24th 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.
(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 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.
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&sessio
n=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=4369
20>.
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_s
poofing.html
