[ISN] Homemade GPS jammers raise concerns

From: InfoSec News (isnat_private)
Date: Mon Jan 20 2003 - 00:58:39 PST

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    By Bob Brewin
    JANUARY 17, 2003
    Government officials and communications experts are assessing the
    public safety and security implications of a newly posted online
    article that provides directions for making cheap devices that can jam
    Global Positioning System (GPS) signals.
    Information in the article that appears in the current issue of the
    online hacker magazine Phrack potentially puts at risk GPS devices
    used for commercial navigation and military operations, authorities
    The Phrack article provides a detailed guide to building a low-cost,
    portable GPS jammer out of components that can be easily obtained from
    electronics supply houses. According to the article, the "onslaught of
    cheap GPS-based navigation (or hidden tracking devices) has made it
    necessary for the average citizen to take up the fine art of
    electronic warfare." Electronics and GPS experts who read the article
    this week called it technically competent and said amateurs with a
    certain amount of technical skill could build a GPS jammer from the
    Although the article said the jammer is designed to work only against
    civil-use GPS signals broadcast on the frequency of 1575.42 MHz and
    not the military frequency of 1227.6 MHz, James Hasik, an
    Atlanta-based consultant and author of the book The Precision
    Revolution: GPS and the Future of Aerial Warfare, disagreed.
    Hasik said that while the Phrack jammer is targeted at civil GPS
    signals, known as the C/A code, it could also threaten military
    systems, since "almost all military GPS receivers must first acquire
    the C/A signal" before locking onto the military signal, known as the
    P(Y) code.
    Hasik said that GPS receivers are especially vulnerable to jamming
    because of low signal strength after traveling 20,000 miles through
    space from GPS satellites.
    The U.S. Department of Defense, which faces the possibility of having
    its GPS-guided weapons come up against Russian-made GPS jammers in
    Iraq, has antijamming technology at its disposal. Still, Defense
    officials viewed the Phrack article with concern.
    Air Force Lt. Col. Ken. McClellan, a Pentagon spokesman, said the
    implications of homemade jammers described in the article are
    "somewhat serious" because the use of such jammers "could disrupt
    commercial operations."
    McClellan said GPS experts at the Pentagon do not "at the moment" view
    homemade jammers as a hazard to flight safety for commercial aircraft
    or ship operations, "but rather a nuisance."
    The Federal Aviation Administration is developing a nationwide
    GPS-based precision landing system. And the Coast Guard operates a
    GPS-based maritime navigation system on both coasts, the Great Lakes,
    inland waterways and Hawaii. Bill Mosley, a spokesman for the
    Department of Transportation, the parent agency of the FAA and the
    Coast Guard, said his department is well aware of the threat posed by
    GPS jammers.
    The DOT's John A. Volpe Transportation Systems Center, in Cambridge,
    Mass., prepared a report in August 2001 that said, "Some jamming
    devices/techniques are available on the Internet and proliferation
    will continue, because a single device that could disrupt military and
    civil operations worldwide would be attractive to malicious
    governments and groups."
    As a result of that study, Mosley said, Transportation Secretary
    Norman Mineta last March ordered an "action plan" to protect civilian
    GPS signals and users by, among other things, "the transfer of
    appropriate antijam technology from the military to civil use." Mosley
    was unable say whether that technology transfer has occurred.
    Richard Langley, a GPS expert and professor of geodesy at the
    University of New Brunswick in Fredericton, New Brunswick, called the
    implications of home-brew GPS jammers "scary." But he expressed doubt
    that the Phrack jammer would be very effective against aircraft when
    used from the ground. However, Langley noted that if a terrorist used
    the jammer from on board an aircraft, it would extend the range and
    "hence the effectiveness of the jammer."
    James Miller, program manager for GPS at United Air Lines Inc., said
    the loss of a GPS signal in a commercial aircraft wouldn't "cause a
    catastrophic event," because airliners operate with multiple
    navigation systems. But loss of a GPS signal by general aviation
    aircraft flying solely on GPS could be "quite challenging," he said.
    Warren Morningstar, a spokesman for the Aircraft Owners and Pilots
    Association in Frederick, Md., said general aviation pilots don't use
    GPS as their sole navigation source and called the potential of
    jamming a "nuisance" rather than a safety hazard.
    "You need to take it seriously anytime there is publicity about things
    that could disrupt the critical infrastructure," said Mike Swiek,
    executive director of the U.S. GPS Industry Council in Washington.  
    But, Swiek said, "there is no need for panic. All the GPS systems are
    monitored for any type of interference." Swiek noted that while "any
    garden-variety radio engineer" has the knowledge to build a GPS
    jammer, there have been few reports of any attacks against GPS
    Gabe Neville, a spokesman for Rep. Joseph Pitts, (R-Penn.),
    co-chairman of the House Electronic Warfare Working Group, said news
    of the Phrack story about jamming indicates that GPS jamming
    technology is "easily available" and that the Pentagon needs to beef
    up its electronic warfare research and development budget. But Neville
    said he doubts a homemade jammer could cause as much damage or
    disruption as systems acquired and operated by foreign governments.
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