"The court heard he was 13 years old at the time of the attack.
The judge told him: "I know you accept that this was a dreadful assault you committed on this little girl.
"One can only hope there will be no lasting effect on her and that she can put it behind her and will forget.
"I accept you had a difficult childhood, which was one of neglect.
"I also accept there is good evidence to suggest you were abused as a child and this helped to form the way you behaved."
Defending, Stephen Townley told the court: "This appears to be a case where a victim becomes an offender, by mimicking behaviour. My client needs help."
The boy will receive counselling from a panel of youth specialists.
They will talk to him about the crime, his behaviour, awareness of the victim, and address his education and training.
He may also be asked to take part in reparation by doing work for the community.
BBC