"The prisoner came up when he wasn't looking and started punching him, up to six times in the back of the head.
"As far as I'm aware it was a random and unprovoked act of violence."
The man was taken to Hawke's Bay Hospital and discharged later that day. Mr Hanlon said a lack of broken bones didn't make the attack any less serious.
"The reality is Corrections will put this down as a minor assault, but we are talking about someone being repeatedly punched. It's one hell of a beating, it's just luck that nothing was broken. For us every assault is serious."
Mr Hanlon wants prison officers trained in one-on-one combat, armed with pepper spray and given Tasers in case of emergencies.
"If we had pepper spray, this kind of attack is unlikely to happen because prisoners will be aware there is a consequence.
"After speaking with staff it is quite clear that this is what staff want."
Mr Hanlon said it was time for the Minister of Corrections to change policies which would allow prison staff to protect themselves.
"The minister must make a decision that reflects that it is disgraceful to have prison officers attacked almost on a daily basis. The police have tools to protect themselves and we have nothing, yet we are dealing with the same people.
"The minister has a chance to fix this or else keep visiting her prison staff in hospital."
It is the third recent assault on an officer at Hawke's Bay Prison to come to the attention of Hawke's Bay Today.
Last month an officer suffered swelling and bruising to his head and face after being hit in the jaw several times in an unprovoked attack in the high-security unit. In July, a male guard was punched repeatedly in the head, while conducting a strip search. He suffered serious fractures to his eye socket and cheek and had ongoing complications as a result.
Mr Hanlon said one of the officers had returned to work.
"He's still got a swollen eye but you can't keep him away from work and he wants to show the prisoners he doesn't care what happens, he still wants to do his job. That is the kind of guy that needs better protection."