Doesn't specify, but I assume the unarmed attacks are finesse? (Can use Dex to make attack rolls)
Actually, no - and keeping the Monk's unarmed strikes Strength-based is intentional. Granted, this makes the class a little MAD - historically, a challenge the class has consistently faced - but it was import to my class fantasy that the Monk, more so than any other class, should be defined by a kind of physical perfectionism.
While making their unarmed strikes function like finesse weapons (as 5E does) is effective, the idea of a monk who can fight well, but is otherwise physically weak, doesn't sit well with me.