What action should merchants take if they suspect fraudulent activity on their Verifone devices?

Merchants should report suspected fraudulent activity immediately to their payment processor because they have the established protocols and resources to investigate such issues effectively. Payment processors are responsible for handling transactions securely, and they can take immediate steps to mitigate any potential losses and protect the merchant and their customers. They can also provide guidance on how to secure the merchant's devices and accounts moving forward.

By reporting the issue, the processor can track the fraudulent activity, monitor other accounts for similar behaviors, and potentially prevent further fraud from occurring. Additionally, they can advise on necessary precautions and changes to operational practices to enhance security against future fraud attempts.

While contacting law enforcement can be appropriate in some contexts, particularly if there is a significant breach or loss, it’s often best to raise the issue with the payment processor first, as they will have the most direct impact on resolving the immediate concern. Ignoring the activity or attempting to manage it without professional help can lead to greater risks and potential financial loss.