The Strømsgodset team captain suffered a broken nose and concussion, and was left needing two stitches to the back of the head.
But the 33-year-old footballer, who has played eight times for his country, said his injuries would likely have been more serious had not his girlfriend, Heidi Bodahl Ekornrød, pounced on one of the attackers.
“I was very lucky. She was very brave and I will be forever grateful that she jumped on him,” Aas told newspaper Dagbladet.
“She’s probably embarrassed because she’s getting so much attention, but this could have been much worse if she hadn’t intervened.”
The pair were on their way home after a night on the town when two men approached and asked Aas for a cigarette.
The footballer told them he didn’t smoke, but instead of continuing on their way the men became aggressive and began pushing him.
Aas said he was wearing shoes that lacked grip, and when he tried to get away he slipped and fell, Drammens Tidende reports.
As he lay on the ground, his assailants immediately began kicking and punching him.
Seeing her boyfriend in distress, Bodahl Ekornrød ran over and jumped on one of the men, who was sitting astride Aas at the time.
She also attracted the attention of passers-by with her cries for help.
As people started to approach the scene, the attackers took to their heels and disappeared.
Aas spent a night in hospital after the attack.
“My nose is broken and needs surgery, so I doubt I’ll be ready for the game against Vålerenga on Saturday,” he told Drammens Tidende.