Though Saints introduced Eoin Doyle and Billy King midway through the second half, it was UCD who finally sparked the game to life on 70 minutes with the lead goal.
The lively Whelan found a pocket of space to pick out Dylan Duffy.
The winger’s low drive was merely parried by Joseph Anang allowing Whelan to sprint in to drive home the rebound for his second goal of the season.
The lead lasted just five minutes though, as McCormack won a penalty when fouled by fellow substitute Kerrigan.
Despite continuing to dominate possession, and winning five corners, the visitors’ trooped off at the break without having worked Students’ 19-year-old goalkeeper Moore on his debut.
The only time the UCD defence looked worried came a minute before the interval when Tunde Owolabi’s header from skipper Ian Bermingham’s cross dropped wide of the far post.
St Pat’s had a little more urgency about them into the second half, UCD having to defend frantically from a Bermingham cross with shots from Owolabi and Darragh Burns in turn blocked before Moore gathered.
Collie Whelan had fired UCD ahead on 70 minutes before McCormack levelled, shooting home the rebound after Kian Moore had saved Eoin Doyle’s penalty.
Both sides made five changes from defeats to Drogheda and Shamrock Rovers respectively on Friday.
The stand outs being UCD winger Liam Kerrigan along with Saints’ striker Eoin Doyle dropping to the bench.
Despite owning the ball from the kick-off, Saints struggled pitifully to trouble UCD in the final third.