A Worm’s purpose is to propagate and spread as much as it can because it’s usually designed to find a specific environment as its target. It differs from a virus in that it doesn’t need a host file to infect and spread. Once the worm reaches its target environment it has limitless options of the end goal from the attacker, like deleting files or delivering other malware payloads like ransomware. Ransomware combined with worms using exploits was made famous with the WannaCry and NotPetya attacks in 2017 that caused over $5 Billion in damage.
Below are some of the known worm variants: