SALEM (CBS) – Salem State University is warning 25,000 current and former students and staff that their social security numbers may be in the wrong hands.

The school sent a letter to those affected on March 11, after detecting a virus on one of their computer drives in February.

“We don’t know that any personal data was compromised, but we’re not taking any chances and have acted proactively to notify anyone with personal data on that drive and offered them free identification protection services,” a spokesperson told WBZ-TV.

The school has offered free subscriptions to identification protection services for those affected.