An investigation into a suspicious withdrawal attempt in 2021 found that an attacker had installed skimmers on several Bank of the West ATMs.

The ATM skimmer is used to forge clone cards that work like the real ones, allowing attackers to empty bank accounts in one go.

“The ATM skimming device that was installed interfered with the normal debit card transaction and allowed the theft of your card number, the PIN number associated with your card, and possibly your name and address. This stolen information may have been used to create fake debit cards and attempt cash withdrawals,” the bank’s notice to compromised customers states.

In notifying customers of the findings of the investigation, the bank noted that it immediately stopped fraudulent use of stolen card information and actively monitored all accounts deemed to have been compromised.

The bank also said it had blocked the debit cards of compromised customers, who will receive a new debit card and PIN. The bank will offer free credit monitoring and identity theft protection services to all affected customers for a year.