Seed to java.security.SecureRandom on Windows os

I am interested in java.util.Random and java.security.SecureRandom classes. I found that Random uses system clock to generate seed and SecureRandom uses /dev/random or /dev/urandom but these files are on Linux, while on Windows it uses some mistic CryptGenRandom. Even if that is super secure function, do we know from where does it take values? What is the basement to generate seed?