A boy was assaulted as he travelled on a bus.
The victim was travelling on the X1 service from Abingdon to Marcham and sat on the top deck on Sunday August 21 at about 10.30pm.
Police are now appealing for witnesses to the attack.
TVP South Oxon and Vale of White Horse tweeted: "If you have any information regarding this incident, call us on 101 or report through out website & quote the reference number 43220375453."