The home side dominated much of the encounter and had taken the lead in the 27th minute when Gonzalo Marronkle's through ball allowed Nguyen Van Quyet to run on and beat keeper Hassan Sunny.
Hanoi went on to miss a succession of chances and they were made to pay for their profligacy in the 80th minute when veteran striker Duric converted a set-piece to ensure a share of the points and preserve Tampines' unbeaten start.
In the other game, Muang Thong United took over leadership of the group with a dramatic 1-0 win over Victory SC at Thunderdome Stadium.
The hosts wasted a succession of chances, the best when Kayem Weerawut was brought down in the box in the second-half, but Teerasil Dangda missed the spot-kick.
However, the forward made amends in the final minute of the game when Amorn Thummanam's back-heel allowed Teerasil to find the back of the net from close range and snatch the points.
Nasaf thrash Dempo
Nasaf took control of Group A in emphatic fashion with a 4-0 win at Dempo. Ilhom Yunusov broke the deadlock after just four minutes and seven minutes later, Nasaf had doubled their advantage after Lutfulla Turaev struck a fine volley from close range that left Dempo goalkeeper Laxmikant Kattimani with no chance.
The visitors put the result beyond doubt in the 72nd minute when substitute Shuhratbek Mirhoidirshaev produced a low strike that found the back of the net and Andrejs Pereplotkins claimed the fourth with eight minutes to go.
Ali Nassereddine scored twice as Al Ansar boosted their hopes of a place in the last 16 with a convincing 4-1 win against Al Tilal. In a game that had been switched to Prince Mohammad International Stadium in Jordan, it was Al Tilal who went in front after 25 minutes through Geleta Lami.
However, Al Ansar came roaring back mainly thanks to Nassereddine, who grabbed a goal in each half with efforts from Edson and Mahmoud Kojok completing the scoring.
Group C leaders Duhok dropped their first points of this year's tournament following a goalless draw with Syrians Al Jaish at Al Abbasiyyin Stadium in Damascus. That allowed Al Faisaly to close within a point of the Iraqis after a 2-1 win over Al Nasr in Amman.
Abdallah Al Attar opened the scoring for the hosts after 16 minutes and Abdelhadi Al Mahamareh added a second five minutes later. Francisco Santos scored what proved to be merely a consolation goal five minutes from the end.
Two goals early in the first-half from Firas Al Khatib and Hamad Al Enezi helped Al Qadsia on their way to a third consecutive victory in Group B with a 3-0 triumph over Al Saqr. Saleh Al Hendi grabbed the third for the hosts in the 77th minute.
Tight race in Group E
Finally, Group E looks set to go down to the wire after top two sides Arbil and Al Arouba played out a goalless draw in Iraq. That allowed Al Ahed to take advantage and surge back into the race for a place in the last 16 with a 4-1 win over Al Karamah in Beirut.
The hosts were indebted to three late goals as, after Mahmoud Al Mawas had cancelled out Mahmoud El Ali's first-half goal, the game appeared to be heading for a draw. However, Hassan Maatouk restored Al Ahed's advantage in the 85th minute before injury-time goals first from Hussein Dakik and then Ali Bazzi made sure the hosts walked away with all three points.
Arbil and Arouba now lead the way on five points with Al Ahed on three and Al Karamah propping up the table with two points.