The match played at Viet Tri Stadium in the northern Phu Tho Province was a chance for Vietnam head coach Park Hang-seo to test different formations for the SEA Games 31 squad, and he used 21 players in all.
The second-youngest player, 19-year-old Bui Vi Hao, fetched Vietnam the penalty in the 17th minute when he was fouled inside the box.
From the spot, captain Dang Van Toi slotted the ball into the left corner to equalize after falling a goal behind.
Three minutes earlier South Korea had scored from a set piece.
From a corner, captain Bae Jun-ho crossed in for forward Lee Young Jun to head in from close range past keeper Nguyen Van Toan who managed to reach the ball but could not keep it out.
Neither team created many scoring chances and settled for a draw.
After the game Park said he was happy with the team's performance as the players followed instructions.
"I needed to test the players' ability. I had a good impression of the new players. I think this was an important game."
The teams will play another friendly in Hanoi on April 22.