The accused, who have been arrested, also made an MMS of the boy, which they circulated and uploaded online, police said today.
As per the complaint of the victim's father, the incident occurred on April 11 when his eight-year-old son was playing outside the house in the campus.
Six persons known to him in the neighbourhood took him to the house of one of the accused on the pretext of giving him marbles to play, police said.
The accused then allegedly sexually assaulted the Class IV student and made an MMS, police said, adding that they also threatened him of dire consequences.
The MMS was circulated and that was how the victim's father got to know of the crime. The victim and accused are children of Class IV employees of the university and reside on the campus.
The five accused minors are aged between 14 and 17 years. The five minors arrested by police have been sent to a juvenile home, police said, adding they have seized the mobile phone and investigations were on.