A half-century from Derek Heasley, 35 from Benson and an unbeaten 24 from Peter Gillespie helped Ireland to 208 for 9 in their 50 overs in reply to the Africans' 215. Ireland will now face the loser of the other semi-final between Scotland and Bangladesh, with a place in the 1999 World Cup at stake.
Benson, who had eight seasons at Leicestershire, said: "Their spin bowler Asif Karim was the real difference with his four wickets."
It could have been different had Alan Rutherford not missed the chance to stump the Kenyan captain, Maurice Odumbe, when he was on 17. Odumbe went on to make 67 and claim the man of the match award.
Ireland expect their vice-captain, Alan Lewis, to return for Thursday's play-off. A ball hit him in the chest in a group game.Reuse content