Malware: viruses, worms and ransomware
Computer Science · Key Stage 3 · The School
A virus needs a host
A computer VIRUS attaches itself to a real file or program. It spreads only when a person opens that infected file or runs that program. No person, no spread. This is why early viruses travelled on shared floppy disks and later on email attachments — both need a person to click.
A worm spreads on its own
A WORM does not need a host file or a person to click anything. It finds a weakness in software across a network and copies itself through that gap, machine to machine, automatically. A single worm can infect thousands of computers in hours, because nothing is waiting on a human decision.
Ransomware and the choice it forces
RANSOMWARE encrypts a victim's files, then demands payment for the key that unlocks them. Paying does not guarantee the files come back, and it funds the next attack. The real defence is BACKUPS, kept somewhere the ransomware cannot reach and touch, so encrypted files can simply be replaced rather than ransomed.
Imagine one unpatched flaw in an operating system. A VIRUS-style attacker might use it once a person opens a bad attachment. A WORM-style attacker uses the exact same flaw to spread itself across a whole network with no click needed at all. A RANSOMWARE gang uses either route in, then encrypts every file it can reach and demands payment. One flaw, one hole in the software — three very different attacks, depending on how the attacker chooses to walk through it. That is why patching a known flaw quickly matters so much: it closes every one of these doors at once.