
Originally Posted by
Lint
Sounds like you may have been a victim of card skimming. Your bank may have sent you an alert about this through email.
If you've ever handed your card to the waiter at a restaurant (or similar situation) they can put your card through a scanner to copy it's magnetic info AND your personal signature.
Alternatively if you've used your card at an ATM they may have scanned your card by installing a faux card reader and overhead camera (to read your pin when you key it in) on the ATM itself. The equipment they install are usually well sculpted and are not obvious unless you're deliberately inspecting.
To protect yourself, try not to withdraw cash from ATMs, especially ones that are isolated or facing the street where its not so busy (harder for them to install their gear if theres always people around), always cover your hand when you key in your pin and inspect the ATM for dodginess before use.