St. Mary's Bank, a state-chartered credit union in Manchester, N.H., recently notified all its 115,775 New Hampshire customers of a possible data breach.

In late May, the credit union discovered malware on an employee workstation computer. An analysis found that the malware was designed to capture information as it appeared on individual computer screens and could have been introduced on 23 computers.  The credit union brought in independent security experts to analyze its entire computer system and eliminate the malware.

St. Mary's has found no evidence that personally identifiable information was acquired by an authorized individual. Still, the credit union is offering its customers a year of free credit monitoring and identity theft protection services from Experian.