Authorities said Wednesday they had paid out US$14,750 in prize money to the best of the 264 so-called "white hat" hackers -- specialists who seek to break into networks to check for vulnerabilities -- involved in the project.
The programme, which ran from mid-January to early February, was introduced after an embarrassing breach last year which saw hackers steal personal data from about 850 military servicemen and other employees from a defence ministry web portal.
It was run with cybersecurity network HackerOne, which specialises in coordinating "bug bounty programmes" in which hackers are rewarded for spotting weaknesses in computer systems.
The top hacker in the contest was a Cyber Security Manager from Ernst and Young Singapore who gave his name only as Darrel and goes by the online moniker "Shivadagger". He was awarded US$5,000.
David Koh, the defence ministry's cybersecurity chief, hailed the project. "Our systems are now more secure," he said.
While Singapore has some of the most advanced weaponry in the region, Koh said the ministry was at increasing risk of being targeted, and attackers could range from high-school students in their basements to criminals and state-actors