If stolen, it could be sold on the black market in an underground international Internet chat room for as little as $6 to $18, law-enforcement and security experts say.

Sound outrageous?

Maybe, but not to FBI spokesman Paul Bresson in Washington. He said there's been "a real explosion of trading and forums on the Internet. It's an underground market operated by people who don't really know each other, but it's very organized."

There is no indication that personal information on the 500,000-plus state employees, dependents, taxpayers and others is being used illegally after a backup data tape was stolen from a state intern's car 10 days ago. Officials emphasize that it's highly unlikely the technical information could be accessed and used.

But based on the potential to mine crucial personal information on 500,000 individuals, Ohio's lost data could be marketed for more than $5 million, estimated Zulfikar Ramzan, senior security expert for Symantec, a California-based software-security firm.

"That's not counting any of the future repercussions," he said.

"This is a huge underground economy … I don't think anyone understands the magnitude of it."

Although there's always the danger that stolen information could be used directly by criminals, the greater threat comes in Internet trafficking of harvested information, security officials say.

"Cybercriminals continue to refine their attack methods in an attempt to remain undetected and to create global, cooperative networks to support the ongoing growth of criminal activity," Symantec said in a March report.

Ramzan said that credit-card numbers, including verification numbers, sell on the Internet for from $1 to $6, while entire identities -- bank accounts, credit-card numbers, date of birth and Social Security numbers -- go for $14 to $18. In the lingo of the criminals, those are known as "fulls."

FBI spokesman Bresson said stolen information is traded in Internet chat rooms, known as online fraud forums or carder forums.

"One person may have passwords. Another may have bank routing numbers and somebody else has a way to make credit cards," Bresson said.

In this specialized business, brokers deal in large volumes (such as 50,000 personal identification numbers) and earn commissions for sales and transactions.

While credit-card numbers are valued, Social Security numbers and bank routing numbers (used to make direct deposits for individuals and businesses) are also hot commodities, the FBI spokesman said. Names and addresses alone aren't of particular value.

The traders are worldwide, Bresson said, with many reports mentioning stolen-data trading thriving in Russia.

ajohnson@dispatch.com