A $70,000-a-year electrical engineer straight out of college, Sun had reportedly changed D and F grades to A's. He also changed some of his girlfriend's A's to an A-plus, reported Gawker
The Lafayette (Indiana) Journal & Courier reported
Sun first hacked into a professor's computer account and changed his grade in 2008. He said he volunteered to be the guinea pig to see if he and fellow Purdue student Mitsutoashi Shirasaki would get caught. They didn't, which emboldened Sun.
"When I came back in 2009, I felt really arrogant," he said during the sentencing hearing. "I thought I was untouchable.
"It became so much easier to change my grades than going to class and working real hard."
So with the exception of one course, Sun quit attending classes his senior year and still received straight A's.
Sun was able to hack into the system by sneaking into professor's and administrator's offices to switch out usual keyboards with a key-logging version at the university
. This record allowed him to collect their university usernames and passwords.