Explain like I'm five · Security

What is Malware?

Malware, told as a story about a bug that sneaks in inside a gift box.

sweepfixreadwritea tool does what it's told — that's a program

The castle is full of working tools.A tool does what it's told. That's a program.

FREE GIFTthe thief gives the ordersa gift box outside, a bug inside

Some tools were made by the thief.A gift box outside, a bug inside — and the thief gives the orders. Exactly the free gifts in the alley.

opens doorswatches and writes downlocks chestsspreadsmany ways in; what it does once inside, the thief decides

Malware is a bug that does whatever the thief says.There are many ways in; what it does once inside, the thief decides.

The gift boxa Trojan
The self-spreading bugworms, viruses
The peeking bugspyware
The lock bugransomware
clipped to a fake letterhidden in an alley boxthrough an open doorinside something you foundletter, box, door, found object — all four need watching

Bugs come in by many roads.Clipped to a fake letter, hidden in an alley box, through an open door, inside something you found.

the bug albumchanged its colornot a face in the albumWOOF!a bug holding the castle's broomthe dog watches behavior, not faces

Some bugs change their faces.The album (antivirus) catches known faces only. So the dog watches behavior. Bugs that borrow the castle's own tools are the hardest.

In one breath

Malware = a tool the thief made and slipped into the castle — a bug that opens doors, peeks, locks and spreads on the thief's orders.

Malware is short for malicious software. Viruses, worms, Trojans, spyware and ransomware are all kinds of bug. Defenses: box checks (SWG), the album (antivirus), the dog (EDR), fixing open doors (patching).

When grown-ups say it

Trojan
The thief inside the gift. Comes in looking like a good tool. You open it yourself.
Virus
A bug that rides other tools. Move the tool, and it comes along.
Worm
A bug that crawls the hallway on its own. Room to room, with nobody carrying it. → the hallway watcher
Spyware · keylogger
The bug that peeks and writes down. Watches your fingers type the password.
Ransomware
The lock bug. → the thief's lock on every chest
Signature · antivirus
The bug album. Catches known faces only. → same idea as the wanted posters
Patch
Fixing the open door. Closing the hole the bug came through. Delay it, and the next bug arrives.
Fileless / living off the land
A bug that borrows the castle's tools. Brings no tool of its own, so the album has no photo. Only behavior gives it away.
Next story
The Hole Nobody Knows About →
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