NEW YORK (CNNMoney) -- The Rapiscan scanner can see your private parts, but it can't see your gun.
That was the finding from a joint study conducted by three universities, who were able to slip guns through a Rapiscan body scanner without being detected.
"Frankly, we were shocked by what we found," said J. Alex Halderman, a professor of computer science at the University of Michigan, in a statement. "A clever attacker can smuggle contraband past the machines using surprisingly low-tech techniques."
The research team -- from the University of Michigan in Ann Arbor, Johns Hopkins University in Baltimore and the University of California in San Diego -- said they managed to conceal guns and "plastic explosive stimulants" from a Rapiscan Secure 1000 scanner.
This is the type of full-body X-ray scanner used in U.S. airports from 2009 until last year, when they were removed because of privacy concerns, the study said. They are now being used in jails and courthouses.
Another researcher, Hovav Shacham, blamed the security weaknesses on the Rapiscan company's assumption that the "attackers" would not be able to test the scanner. But he said they were able to buy a government surplus machine on eBay.
The scanners cost from $150,000 to $180,000 when they were distributed by the Department of Homeland Security to airports throughout the United States. The government installed 150 just in 2010, but many passengers objected to the scanners' ability to see their private parts.
Rapiscan, a subsidiary of OSI Systems in Hawthorne, Calif., was not immediately available for comment.
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