I know that attack in the front is risky because bison's horn, but would wolves do that if say they encountered human?
What wolves would do if they encountered a human would be to turn tail and run, usually.
Sometimes wolves are curious. They may stand and look at you, taking their sweet time to check you out. If it is a pack, they may also follow you or approach you. As far as I know, there still is no proven wolf attack (wolf bites person) on humans by wild wolves (wolves that have not been fed by people, wolves that do not live in an enclosure).
My boyfriend was approached by a pack of 13 two winters ago - he was out on a frozen lake and they noticed him and came to check him out. When it got a bit too unnerving, he whistled and they turned an ran.
Another guy I know was approached by three wolves while out cross country skiing. They started closing in on him and running alongside. He made threatening gestures with his ski poles and they ran away.
Our neighbour had two wolves hanging out in his yard on and off for about three weeks this winter and shooed them off by shouting when it got on his nerves.
On northern Ellesmere Island, where my boyfriend spent some time this year, the wolves have never been hunted by humans. They will approach and sniff people's pants, much like dogs. Although they have hardly any fear of humans, they have not been known to attack anyone.
Predators tend to prey on the animals they've been preying on for generations. The Yukon reintroduced bison, which have been extinct here for hundreds if not thousands of years, assuming that the wolves would keep the population in check. Not so. Because bison show a different defense behaviour than moose and caribou, the mainstay of Yukon wolves, they didn't know what to do. After 40 something years of bisons in the Yukon, the wolves are just now finally catching on to how to kill them. This is partly also why llamas work as livestock protection - the predators find their body language too weird and intimidating, so instead of just killing the llamas that "guard" a herd of goats, they back off. Most wild animals will not risk injury to themselves unless their survival is at stake. There is a dialogue going on between predator and prey.
This is why, IMO, wolves don't attack humans. For one thing, we are just not part of their menu, just like the reintroduced bison in the Yukon and the llamas, and when they do check us out, we don't give the prey response that would trigger an attack - we don't show weakness, we show aggression.
We live out in the bush; actually, I just watched a wolf cross the lake this morning. If you need some facts about wolf-people encounters that are not gleaned from books and the internet, but actual personal experience, pm me