I don’t think they had enough power to do too much. They were used for reconnaissance, and of course they were used to rescue wounded soldiers. Some of the heavier Sikorsky’s were used to ferry troops into battle but the pilot’s seat was mounted high in the craft which made him an excellent target for the enemy. But there were no armored attack helicopters like we have today, or like the Cobra gunships of Viet Nam.

Interesting little factoid from Wikipedia:

In the opening months of the Korean War era, in August 1950 a joint US Navy and Marine Corps test used a newly acquired Bell HTL-4 helicopter to test if a bazooka could be fired from a helicopter in flight. One of the larger 3.5 inch (90mm calibre) models of the bazooka was chosen, and was mounted ahead and to the right of the helicopter to allow the door to remain clear. The bazooka was successfully tested, although it was discovered that it would require shielding for the engine compartment, which was exposed in the model 47 and other early helicopters. The helicopter itself belonged to HMX-1, a Marine experimental helicopter squadron.[

Yes, helicopters were used for military offensive purposes, but not, as far as I know for direct attack using weapons mounted and fired from the helicopters.

At least three of the types of helicopters used in the Korean War have been fitted with weapons (e.g. machineguns and sometimes rockets), or at least have been since then – I’m not sure if they were during that war.

The military offensive purposes they were used for were air assault missions as transportation. That is, they were sometimes used to bring foot soldiers quickly to otherwise-unreachable (especially not so quickly) places from which the foot soldiers then launched attacks. They tried to keep the helicopters themselves away from enemy fire. They also resupplied fighting units and evacuated casualties, both of which enabled the men to do more fighting than if they were not supported by helicopters. They were also sometimes used to quickly move indirect-fire batteries (e.g. rocket launchers) to avoid hostile counter-battery fire by providing quick relocation after firing.

Related articles:
http://www.historynet.com/the-rise-of-the-helicopter-during-the-korean-war.htm
https://www.army.mil/article/177302/