Is a female student considered sinful for giving her internet password to her friend without her parents' permission, and is it permissible for her to use household items without informing them?

It is not permissible to dispose of another person's right without their permission, whether the disposer is a child or a wife. The proof for this is the Prophet's (peace and blessings be upon him) saying: "Indeed, your blood, your wealth, and your honor are sacred among you, like the sanctity of this day of yours, in this month of yours, in this land of yours." And his saying: "The wealth of a Muslim person is not lawful [for another] except with their willing consent." Accordingly, it is not permissible for a daughter to give away anything from her father's rights except with his permission. She must seek his permission before disposing of his rights, except for what the father has explicitly or customarily allowed, or what is commonly practiced.