Unfortunately, McGruff the Crime Dog may be wrong. Crime can pay for many creative criminals who use sneaky means to swipe financial data, at least until they get caught. One method of financial crime is credit card sniffing. Sniffers don't touch your card -- they just steal its information as it passes over computer networks.

Hijacking Technology

Originally, network administrators used sniffing to detect problems on their computer systems, and they've been using it for decades. Sniffers are so legitimate they are made by major software companies. However, the software's power to intercept traffic for legal purposes can also be used for illegal ones, like detecting the transmission of credit card numbers.

Tapping In

When criminals sniff credit card information, they compromise the networks that transmit the data. By installing sniffers at corporate servers, they are able to capture all of the information that flows in from the company's credit card terminals. This allows them to steal thousands or millions of credit card numbers and capture enough information to make fake cards or do online transactions with them.

Sniffing the Air

New credit cards that contain chips to allow you to do "swipeless" transactions can also allow credit card skimming, or sniffing on a much smaller scale. Despite its benefits, "near field communication" technology can let thieves connect to your card and take its data, using radio frequencies. Now that this NFC technology is being built into cellphones, credit card thieves can use an app to steal credit cards and then use the phone like a stolen card.

Protecting Yourself

To protect yourself from NFC skimming, you can ask your credit card company for a card that doesn't allow swipeless transactions -- or you could buy a metal-lined wallet that blocks NFC transactions. Guarding against large-scale sniffing is harder because it happens at a level that is usually out of your control. The best way to protect yourself there is to keep a close eye on your credit card bills and debit card statements. If you see any charges that don't look familiar, contact your card company immediately.