I want to know that if using kangaroo, I could find three points supporting physically and safely square box .
how can i find three points using kangaroo?
There isn’t really enough information here to answer the question!
Guessing a bit at what you mean - I don’t think you need Kangaroo for this though.
If three points on a solid are fixed against translation in all directions, and they don’t lie on a common line, the solid is also fixed.
If by supports, you mean they only resist in the vertical direction, then the center of mass needs to lie within the triangle formed by the three support points when you project them onto a horizontal plane.