A computer worm is a type of malware that infects a computer, replicates and spreads to other computers.
Worms are programmed to use computer networks to send copies of themselves to other computers, meaning that they do not require a cyber criminal’s guidance to spread.
A common function of a worm is to install a ‘backdoor’ on the computer, allowing the worm author to take control of it.
A worm will typically use a computer network in order to spread itself and relies upon security failings in order to access it.
How does a worm cause damage?
Typically the harm caused by a worm is a by consuming bandwidth and by corrupting or modifying files.
However, many different worms have been created, lots of which only seek to spread, but others like the Morris worm and Mydoom, are capable of causing major disruption.
Although these worms did not carry a payload, they did cause major disruption by increasing network traffic, which slows down systems and the ability of an organisation to operate properly.