Your Mobile Phone Could Get Hacked, Too

Thomas Martin is president of Martin Investigative Services Inc., based in Newport Beach, Calif., and author of the newly released book Seeing Life Through Private Eyes: Secrets From America's Top Investigator to Living Safer, Smarter, and Saner.

Why are cell-phone numbers popular with criminals? In the mid '80s, when the cell phone came out, it was used to make phone calls, just like the regular phone in your house. Now our whole lives are on our smartphones. Once criminals get your number, they can get your e-mail, texts, photos, purchases you made online and the credit card information that you used to make those online purchases.

How can crooks get cell-phone numbers, and what happens when they do? They can hack the cell-phone providers, such as Verizon or T-Mobile, and get batches of cell-phone numbers, which can have from 500 to 5,000 numbers in a single loop. Then they send out a text, such as "Here's $20 off tickets to the local theater," or "Here's a $10 gift certificate to In-N-Out,” that contains so-called Trojan-horse malware. Once you click on the link, they have verified your number and have access to your cell data, such as your photos and other information that they can use to try to blackmail you. Or they can capture your date of birth and Social Security number to sell to identity thieves.

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You've said that crooks can get cell-phone numbers from databases, too. Who compiles those databases? The databases that are out there are compiled by all kinds of people. Some online companies sell customers' data, including cell numbers, and other information about what products people are buying that can be used for marketing purposes. The problem is that cell-phone numbers aren't regulated in the U.S., so there are no rules requiring companies to keep the numbers private.

What can people do to protect themselves? One way is to have more than one mobile phone. Use one phone only for calls—that's the number you give out. Don't put any photos on it, don't text with it, and don't e-mail on it; save that for the other phone. If having two phones isn't practical, just be a little more cautious about who you give your cell number to. If you have a landline or work number, it's better to give those out. If it were up to me, the order would be landline number first, then office number and then cell-phone number at the very end.