The University of Wisconsin-Milwaukee said Wednesday it was warning about 75,000 people, including current and former students and employees, about an incident where names and Social Security numbers were possibly exposed to hackers.

According to a letter obtained by WTMJ, members of the UWM technology staff discovered on May 25th that people had installed malware on a server that had a software system storing confidential information.

The letter said the school shut down the system, check into its security, then restarted it.

A month later, the school found out that hackers had access to a database in that system with the names and Social Security numbers of around 75,000 people.

According to the university, investigators don't know who the hackers are, but the investigators' theory is that the hackers weren't trying to commit identity theft.

The letter also claims that there was no evidence showing hackers tried to download names or Social Security numbers.

The school says it's giving affected people information on ways to check their credit and protect their personal information.

Also, the school says it has put new security measures to protect its IT systems