Attacks against previously unknown vulnerabilities that give network security specialists virtually no time to protect against them are referred to as:

cyberstalking on the internet means to harass or stalk someone, a group, or an organization. this may include defamation, slander, and false accusations. in many jurisdictions, cyberstalking is a criminal offense. 

on the other hand, cyberbullying focuses more on intimidating, threatening or harassing someone. harmful bullying include posting threats, rumors, and sexual remarks.