CWMO 2017 Problem 4

Let $n$ and $k$ be given integers such that $n\ge k\ge 2$ . Alice and Bob play a game on an $n$ by $n$ table with white cells. They take turns to pick a white cell and color it black. Alice moves first. The game ends as soon as there is at least one black cell in every $k$ by $k$ square after a player moves, who is declared the winner of the game. Who has the winning strategy?