This is the quick route which can be done during times of the year when the dirt portion of Squaw Peak road is open. Less than 1.5 miles round trip and around 400 feet of vertical gain.
Getting There & Route Description
From I-15, take the 800 North Orem exit and proceed east until you reach Provo Canyon. Proceed up Provo canyon a couple miles until you reach the turn off on the right for Squaw Peak Road. Take Squaw Peak Road all the way (about 4 miles) until the split and go left towards Hope Campground. Proceed on the dirt road past Hope Campground about 2.5 miles until you come to a left cutback in the road that lies due east of Buffalo Mountain. You will see an opening in the fence and a steep trail up to it heading west from the road. Follow this trail west 1/3 of a mile until you reach the T intersection that comes up from Sunset Overlook. Proceed Straight and directly up the trail on the Southeast ridge 1/4 mile to the summit.
See Eric Willhite's fantastic trip report here (which is admittedly better than this page currently):
Willhite Web Buffalo Trip Report