system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does Anti-cheat systems like PunkBuster or VAC work?

Just wondering how it works and how it can be improved?
gpt
tl;dr: Similar to antiviruses. Match memory with database, block anything found.

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In ELI5 terms:

Imagine you're going to cheat on a test. Some guy gives you a cheat sheet, tells you these are the answers to the test. You put the cheat sheet in your pocket and use it to pass the test. Now, suddenly, everybody starts passing the tests. So teachers hunt down your friend and after investigating him, they notice that he's giving people cheat sheets.

Now, in an attempt to stop this, teachers start patting down students taking tests looking for "cheat sheet". Soon as a matching cheat sheet is found, the student is banned from taking the test.

So your friend ups his game and now starts sending text messages to students with the cheats. Teachers notice that something's weird when students start passing all tests. They investigate your friend, notice he's sending texts, and now teachers start searching students for "cheat sheet" and "mobile phone".

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Something like PunkBuster reads the player's computer's memory for matching signatures existing in the database. Every software you run exists in your memory as it runs and has a particular footprint. The developers of PunkBuster study these bots, find out what they look like in memory, and put it in a database. PunkBuster then scans your memory and if anything fits the signatures in the database, it blocks you.

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PunkBuster has a bunch of other functions to make it more efficient. But this is the core.