Just in time for summer vacation, cybercrooks have a new destination: your frequent-flier miles. Stealing travelers' airline rewards seems to be the latest form of identity theft, according to Internet security watchdog Kaspersky Lab.

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It's done by sending out millions of spam emails that purport to be flight confirmations, special offers or travel alerts. Each one requests reward program membership numbers and passwords.

"A sense of urgency is important, and that'll make people give up their details," says Kaspersky's Tim Armstrong.

If there are are enough miles to redeem a flight, scammers cash in — often selling tickets to third parties.

Plus, when links provided in these bogus emails are clicked, "they will infect the computer with malware and just steal money out of people's accounts directly."

Protect yourself: When in doubt, directly contact your airline to vet the authenticity of any travel-related email you may get.

If you think that's sneaky, watch out for these other tricky travel scams:

• The Pizza Pilfer

When you're staying at a hotel, pizza delivery flyers may be slipped under your room's door. After a tiring day of sightseeing, a cheaper alternative to room service, you say?

Some food for thought: Order from these photocopied flyers, which may only provide a telephone but no address of the restaurant, and you may be asked to give a credit card number.

Do that, say Orlando police, where this scam proliferated at hotels last summer, and scammers may either use your account number and confirmation code to make fraudulent big-money charges, charge you for the pizza that's never delivered or, at best, give you "a very inferior pizza that, in some cases, is made in unsanitary conditions."

Protect yourself: If you're hungry for room delivery, ask the front desk for reputable area vendors. Pay only cash after food is delivered.

Next: Don't pay unreasonable cab fare. »