What is the ruling on forging a university doctor's signature, knowing that attendance affects grades?

Falsifying a doctor's signature by imitating it and attributing it to him is a forbidden lie and an invalid deception, especially if it leads to injustice to others or circumventing a right. Sacred texts have prohibited falsehood and deception, including the Almighty's saying: (And shun false statements), and the Prophet's (peace be upon him) saying: "Shall I not inform you of the greatest of the major sins?... Associating partners with Allah, disobedience to parents, and indeed, false speech and false witness." Also, his (peace be upon him) saying: "Whoever cheats is not of us," and "Cunning and deception are in the Hellfire." The perpetrator of forgery is to be punished because it is a sin for which there is no prescribed punishment (had) nor expiation (kaffara). Forgery is defined as imitating another person's handwriting, or every statement or action intended to adorn falsehood so that it is thought to be truth, whether in speech, like false witness, or in action, like imitating handwriting with the intention of establishing falsehood. Forging a signature falls under the forbidden forgery encompassed by the hadith: "Whoever cheats us is not of us."