A wanted poster for harmful files
A police station keeps a wall of wanted posters. When someone walks in, an officer checks the face against the wall.
Anti-virus software works the same way. It keeps a long list of known harmful files and checks every file against it.
By the end of this lesson
Note
I can say what anti-virus software does, what it cannot do, and how to keep it useful.
Key words
| Word | What it means |
|---|---|
| Anti-virus | software that finds and stops known harmful files |
| Malware | harmful software |
| Signature | a short code that identifies a known harmful file, like a fingerprint |
| Definition update | a new list of signatures sent to the anti-virus software |
| Established threat | a threat that has been seen before and is already known |
| False positive | a safe file wrongly marked as harmful |
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Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
How anti-virus works
The software holds a list of signatures. When a file arrives or is opened, it makes a signature of the file and looks in the list.
If there is a match, the file is blocked or put in a safe place. Some products also watch how a program behaves.
What anti-virus does well and where it fails
| Situation | Result | Why |
|---|---|---|
| A virus seen a month ago | Caught | Its signature is in the list |
| The list was last updated a year ago | Missed | New threats have no signature on the old list |
| A brand new threat | May be missed | No signature exists yet |
| A safe program that looks odd | False positive | The check was wrong this time |
The cells students fill in are left blank in this preview.
Keeping anti-virus useful
Three habits matter. Install it on every computer and server. Let the definition updates run every day. Scan on a schedule as well as when files arrive.
In a cabled office, the RMM tool can check that every machine has it and that its list is current.