In an email Wednesday, Penn officials confirmed the data breach but said it was limited, The Philadelphia Inquirer reported.
"Fortunately, no sensitive information that could result in identify theft, such as Social Security numbers, PennKey passwords, bank account numbers, or credit card numbers are contained in the database that was compromised," the email said.
A hacker group called Team GhostShell took credit for the breach, posting a short statement on the Web citing problems in educational institutions including the mounting burden of student debt.
"We have set out to raise awareness towards the changes made in today's education, how new laws imposed by politicians affect us, our economy and overall, our way of life," the hackers said in their posting, which included links to sites where the stolen information was posted.
The affected database at the university was taken off-line and the problem has been fixed, school officials said.
Similar breaches were experienced at Harvard, Stanford, Duke, Purdue, Rutgers, Cornell, and Johns Hopkins, while the Universities of Tokyo and Cambridge in Britain were among those hit outside the United States, the Inquirer reported.