I may be wrong so don't hold me to it but I would hazard a guess your son is navigating the pecking order at school with the boys and this is the result and it's bled out into your home life.
I can say from my experience at school from the moment secondary started there was a never ending power struggle within the boys and there were almost like factions of popularity and dominance between them. It was very much a case of you were being consistently tested by others to how far you would go, how strong you were and what you could deal with, which then in a way determined where you stood in that pecking order.
If you didn't bend you were generally bullied and attacked, some like me stood their ground and were left alone in the end and just coexisted between them all. Others didn't stand their ground and were the punching bags for the remainder of the time. The rest joined and became the same. The only way I can describe it is like gang mentality or an animal hierarchy of dominance. The behavior sounds the same, a total disregard to authority, goading it was the same then.
Bare in mind also my school won awards year after year for being an anti bullying school. They did nothing there was no support they only did on oftsed days. My school at least was like a prison without rules even the teachers were assaulted often, but to parents it was amazing school. It was not.
So, I would say he's acting this way because he's been made to believe that's how he should and depending on his makeup maybe that's gone further. At my school, someone who was so defiant they would do stuff like that to adults and own parents were nearer the top, don't push that one he's a live wire none can control him.
No way would he talk to a counselor at school, not even I would, you would be asking for it and that would throw you in a shit storm. What he's doing is pushing back against it, can't control me and that image then goes back to the friends.
Unfortunately I don't know what the answer is but I would say look at school, some like mine made up all kinds of shit to save their own record. You could move schools but he may fall into it again or may still have contact.
All I know is boys on that path need to see consequence before they go too deep and shouting and smacking isn't it because they are already likely witnessesing that, it won't phase them. Needs consequence as in where his life will be if he continues that route into adulthood, I dunno show him where people like that end up in life or worse prison. Show him what he has that others do not, make him live a life without luxury for a while see what he has lost from the behavior. Make him do things to help it will be hard but it's a battle of wills don't back down, you back down it's lost.
If you need counseling don't do it through school do it so others don't know because they will know at school gossip and eyes everywhere.
Hope that helps, as say could be wrong just another perspective on it.