STATE COLLEGE — A cybersecurity sweep at Penn State University found the Social Security numbers of another 25,000 individuals might have been exposed to a security breach because of infected computers.

But the university said that, as in previous cases, there was no evidence data had been accessed after the computers were hit by malicious software or so-called "malware." Malware refers to software that can silently install viruses, probe for confidential info or even hijack a computer.

Individuals affected by the privacy breaches were notified as required by state law to look out for potential identity theft, Penn State said.

One recent case involved a University Libraries computer breached with malware. The computer contained the Social Security numbers of more than 9,700 people. In another case, the school last week sent letters to more than 15,800 people about a possible breach at an Outreach Market Research and Data computer. The attacks in those cases occurred some time earlier this year, school spokesman Geoff Rushton said today.

Another 35,000 individuals were notified late last year and earlier this year of potential breaches at the main University Park branch as well as campus sites in Carlisle and Schuylkill Haven.

In each instance, infected computers were taken offline and wiped clean before being reinstalled. "Basically, the computer is starting over," Rushton said.