Santa Clara University's academic records database was recently hacked to improve the grades of more than 60 former and current undergraduate students, the university said.
The university called in the FBI, which is assisting in the ongoing investigation, according to a Mercury News report.
"We are taking it quite seriously," said Dennis Jacobs, Santa Clara's provost and vice president for academic affairs, in the report. "We are reviewing and enhancing all security measures to reduce the likelihood of any intrusion in the future."
The report said that the incident was particularly sophisticated, and was only discovered when a former student came forward in August because she noticed a grade on her transcript was better than the one on a previously printed transcript.
SCU officials launched a probe that reviewed tens of thousands of student records going back more than a decade.
Hacking into the system sometime between June 2010 and July of this year, the cyber-intruder made changes that ranged from subtle upgrades to major changes that turned F's into A's.