Murdock struck five fours and cleared the boundary ropes twice in a chanceless innings to guide Brigade home in a textbook run chase.
He was given excellent support by Matthew Gillespie (30) and Tom Wray (22) as the Beechgrove side passed their 170 run target with five overs to spare.
Earlier, the experienced pairing of Alan Waite and Michael Hingston scored half centuries in a 105 run stand after Mark Simpson (3-25) and Nick Donnell (2-24) had taken early wickets to leave the Mid-Ulster side reeling on 14 for 3.
Waite top scored with an undefeated 57 from 100 balls (4 fours), while Hingston also struck 4 fours and one maximum in his 53 from 83 balls.
James Mitchell gave the innings some late impetus as he struck two sixes on his way to a breezy 20 from just 10 balls, as Waringstown closed on 170 for 7.
It wasn't to be enough as Brigade's batting showed maturity beyond their years to clinch the trophy.
O'NEILLS ULSTER PLATE FINAL
At Magheramason,
WARINGSTOWN II's 170/7 (40 overs, A Waite 57*, M Hingston 53, J Mitchell 20, M Simpson 3-25. N Donnell 2-24)
BRIGADE II's 171/5 (35 overs, D Murdock 75*, M Gillepsie 30, T Wray 22)
Brigade beat Waringstown by 5 wickets
