Verifone, the largest maker of credit card point of sale terminals in the U.S., which assists various industries, including retailers, with credit and debit card swipe and process services, has affirmed that it is investigating a breach of its internal corporate network.

According to Verifone’s CIO, it is “investigating an IT control matter in the Verifone environment.”

Verifone send an urgent email to all staff and contractors requiring them to change their passwords within 24 hours and prohibiting them from installing software of any kind into work computers and laptops.

It is being reported by Krebsonline that Verifone was advised of the issue by major credit card companies. Although Verifone originally denied that the intrusion impacted its payment services network, Verifone later confirmed that the intrusion was limited to approximately two dozen gas stations.