France forward Benzema was also fined €75,000 after being found guilty of complicity in the attempted blackmail of former international team-mate Mathieu Valbuena.
It did not prove to be a distraction for Carlo Ancelotti's men, however, as they brushed aside their less illustrious opponent with the minimum of fuss – at odds with their shock home defeat in the reverse fixture.
David Alaba and Toni Kroos put Madrid two goals ahead at the break, and Benzema added a third before the hour mark to seal his side's place in the knockout stages with a game to spare in Group D.
Benzema saw an early goal ruled out for offside after Georgios Athanasiadis had parried Kroos' shot, and the Sheriff goalkeeper got down well to Rodrygo's strike before the midway point of the first half.
Madrid's dominance was rewarded in the 30th minute, though, when Alaba's free-kick from 20 yards was deflected past Athanasiadis for the Austria international's first Champions League goal for the club.
Kroos then doubled Madrid's advantage in first-half stoppage time, stroking in a sublime effort from 20 yards via the underside of the crossbar.
Benzema scored his fifth goal of this season's competition in the 55th minute with a cool strike into Athanasiadis' bottom-right corner from just outside the penalty area.
Sebastien Thill's cross crashed back off Thibaut Courtois' post as Sheriff rallied in the closing stages, yet Madrid held firm to ensure there was no blot on its copybook this time.