The incident was identified in September, when a threat actor accessed a server at Southampton and encrypted the data that was stored on it.
The county says that it took steps to contain the attack immediately after identifying it, and that it launched an investigation into the incident, to determine the type of data that might have been compromised.
The investigation revealed that personal information such as names, addresses, driver’s license numbers, and Social Security numbers might have been compromised, the county says in a notification letter sent to impacted individuals, a copy of which was submitted to the Montana Attorney General.
“Although we have no conclusive evidence that the cybercriminal was successful in removing your personal information from Southampton’s server, out of an abundance of caution we wanted to alert you to this matter and provide you with free credit monitoring,” the letter reads (PDF).
Southampton County also confirmed that the threat actor behind the attack has posted some of the stolen data online.
