A panel of Microsoft employees from the Microsoft Security Response Center (MSRC), the Windows group and Microsoft's research arm will judge the entries.

In last week, Moussouris said that the quantity and quality of the entries -- up to at that point only 10 -- had "exceeded our expectations."

She did not name the participants, but did say that they included security researchers "with great track records," individuals or teams from academia, and others.

From her account, most contributors worked close to the April 1 deadline: Half of the 20 total submissions were filed in the last nine days of the contest, and one squeezed in under the wire with just nine minutes to spare last Saturday.

In fact, Microsoft rejected a submission that missed the deadline by just eight minutes. Moussouris cited "fairness to the others" as well as Washington State contest rules as the reasons why the company wouldn't bend.