What to do if your Mac is compromised
If you think your Mac has been compromised, don't panic. Working through a few clear steps in order will limit the damage and get you back to normal.
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The signs
Warning signs include apps or browser extensions you didn't install, your browser home page or search engine changing on its own, being locked out of accounts, or friends receiving messages you didn't send.
The first steps
Work through these in order:
4 steps
If it's serious
If problems continue, or sensitive data like banking is involved, the safest fix is to back up your personal files, then erase and reinstall macOS using Recovery (hold the power button on an Apple silicon Mac, or Command-R on older models). A clean reinstall removes anything hidden.
Where to get help
The National Cyber Security Centre has plain-English guidance at ncsc.gov.uk, including what to do if you've lost money, in which case contact your bank straight away.
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