I got the interview through Campus Recruitment. The selection was a 4 step process:
1. CV Submission and Shortlisting: They looked at a balance between academic prowess and extra curricular achievements, the cover letter should reflect the same.
Bain & Co. are extremely helpful throughout the process, they're eager to answer your questions and guide you. They even conducted case workshops and an interview guide.
2. Written Round: Data Interpretation (Reading graphs and assigning tags, etc. Mostly multiple choice) and arrangement of slides in a logical coherent order and writing out an executive summary.
3. 1:1 Interviews: Two interviews of guess estimations. The interviewers were nice, though one seemed kinda mean and disinterested.
4. Final Round: Panel Interview with 6 Senior Analysts, consisting of Case Interviews