Smart ID tags that are expected to replace barcodes at supermarkets and luggage tags at airports could be vulnerable to computer viruses, according to research conducted at Amsterdam Free University.

Radio Frequency ID (RFID) tags are about the size of a grain of rice and can be scanned from a distance, without a direct line of site between the tag and the reader. This means that a whole supermarket trolley full of groceries could be scanned with one sweep.

It had been thought that since the tags store relatively small amounts of information that they would not be able to carry malicious programs, but the Dutch researchers have identified a potential vulnerability. They say that a single infected tag "could infect an entire system with disastrous consequences".

The report imagines the scenario of an infected tag being placed on a suitcase that’s presented for check-in at an airport. "As soon as the case is scanned, the infected tag will be able to invade the airport’s central baggage database and all cases subsequently checked in will also become infected," the report states.

"On arrival at other airports, these cases will be scanned again and within 24 hours, hundreds of airports throughout the world could be infected. The perfect solution for smugglers and terrorists wanting to send suspicious luggage across the world without being noticed."

However, security experts at the antivirus company Sophos said that viruses would be unlikely to spread in this way in the real world. "Any data storage device can carry virus code, but it doesn't necessarily mean that the virus would be able to spread successfully," Graham Cluley, the company’s senior technology consultant, said.

He said that the virus code described in the paper works only on the system constructed by the authors to demonstrate the threat. "The researchers who wrote this paper failed to find a vulnerability in the RFID system for their virus to exploit, so they had to deliberately build a system with a problem for their virus to spread."

Greg Day, security analyst at the online security company McAfee, said that the threat was small at the moment but is likely to grow as the use of RFID tags becomes more widespread.

"We've seen viruses less than 1,000 bytes in size, so in theory the threat is possible," he said. "Today we have not seen such an attack. However, as RFID becomes more commonplace, the likelihood of attack could grow."

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