Legitimate defense in jurisprudence is one of the cases that excludes some criminal behavior from the guarantee and gives it legitimacy in the capacity of defense. The Imami jurists have determined its necessity, limits, and gaps by relying on the rules of nature, reason, and citing the verses of the Qur'an and the traditions of the Ahl al-Bayt (peace be upon them). One of the most important categories of legitimate defense is defense against chastity crimes. At present, cyberspace has provided a contaminated environment for committing this type of crime, and on the other hand, it has provided a suitable platform to defend against it. The findings of this research, written in a descriptive-analytical way, show that defense in cyberspace is possible and against some crimes against chastity that are committed with the intention of attacking one's honor and dignity - by observing the jurisprudential conditions such as Al-Ashl, Falasahl- It is possible to defend legitimately by hacking, sending malware to the aggressor's subsidy and tools, counter-threat, etc.