The World Number Two was alongside the leaders on nine under par and will have to return at 6.30am local time on Saturday to finish his last two holes at the Royale Jakarta Golf Club.
Shaaban and Park fired rounds of 67 and 68 respectively to lead by one from Thailand's Thitiphun Chuayprakong (68).
Pariya Junhasavasdikul, who shot the best round of the week so far with a superb 65, is another stroke back on seven under in the clubhouse alongside three other players.
A total of 47 players have yet to complete their second rounds. Thailand's Thongchai Jaidee was eight under with two to play.
Westwood, who reverted to a conventional putter, birdied his opening four holes before making the turn in 32.
He added a birdie and bogey on holes 12 and 13 respectively and birdied the 16th just before play was suspended.
"Obviously I'm disappointed because I had two more holes to play. I'm still in contention and have to see how things go in the next two days," Westwood said.