A vendor that provides software services experienced a cyberattack that exposed the information of thousands of customers, including those of NexTier Bank.

NexTier sent a letter to customers alerting them of the incident at American Bank Systems, which occurred in mid-November.

An investigation by NexTier in partnership with American Bank Systems revealed that the information compromised included the address, date of birth, account number and loan information of certain customers.

Bank officials did not say how many NexTier customers were affected by the third-party cyberattack.

The letter said the vendor took appropriate steps to notify affected customers within seven to 10 business days of the attack.

American Bank Systems is providing affected customers a year of credit monitoring services and identity theft protection at no cost, according to NexTier.

NexTier additionally advised the affected customers to regularly review transactions via online or mobile banking, report unusual account activity and consider requesting a free credit report and placing a freeze or fraud alert on affected credit accounts.

The bank also provided a checklist of steps all customers can take to protect themselves from fraud or identity theft.

“We know that situations such as this can be concerning,” said Cleman C. Rosenberger, president and CEO at NexTier. “Please know that we are working closely with ABS to ensure that they are addressing these issues quickly and thoroughly.”