I was given 2-3 LeetCode-style problems focused on hashing, graphs, and trees. The time limit was roughly 1 hour and 30 minutes. This was the online assessment, and I haven't heard anything after that so far.
The following metrics were computed from 847 interview experiences for the Microsoft Software Engineer (Internship) role.
Microsoft's interview process for their Software Engineer (Internship) roles is fairly selective, failing a large portion of engineers who go through it.
Candidates reported having very good feelings for Microsoft's Software Engineer (Internship) interview process.