Yes, INFILTRATION is a Scrabble word!

Letter values in Scrabble US: I 1, N 1, F 4, I 1, L 1, T 1, R 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

INFILTRATION is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a process in which individuals (or small groups) penetrate an area (especially the military penetration of enemy positions without detection)
the slow passage of a liquid through a filtering medium