A computer worm is harmful because it may perform a broad range of attacks, including crashing systems through self-replication, downloading malicious applications, and providing hackers with backdoor access to equipment.
Worms can also be hard to remediate. Because they spread automatically and quickly, it can take a lot of time and effort to eradicate a worm outbreak from the environment and fully recover. When a worm spreads inside a data storage environment, for example, it can take months to completely clean it up. Even when a worm doesn’t have a malicious payload that does damage, it poses a serious nuisance for IT managers who have to dedicate valuable resources to navigate the incident response process.