You can be sure about the object being the second person (=you, singular or plural, te or ti) because
a) it cannot be a first person (sing. or plural, I/we) because it wouldn't make any sense
b) it cannot be a 3rd person (Sing. or Plural, he she, it/they) because the verb conjugation would be "várjuk" (őt or őket= definite objects and they go with the objective verb conjugation) in such a case.
Although 3rd person (Sing. or Pl.) indefinite objects would go with the original subjective verb conjugation, e.g. várunk valakit.
But in this case either the indefinite object appears (obligatorily) in the sentence or, if nothing appears, you should interpret the verb as just the action, without any object. e.g.
We are (just) waiting (i.e. for something to happen) = Várunk.