Why your Mac wants permission to attach a Thunderbolt or USB device

Apple enhanced the security of attaching and inserting thumb drives, printers, and memory cards to (or into) the Thunderbolt, USB, and SD Card ports on M-series Apple silicon Macs in macOS, stating with Ventura. When anything is plugged or inserted into one of those ports, you’re asked to provide permission to proceed if it’s never been seen by the Mac before. If your Mac is locked, it must be unlocked before you can continue.

The intent is to prevent someone from inserting something that contains malicious firmware or for malicious purposes—like copying the contents of your drive—without explicit permission being granted when the computer is unlocked.

However, you might receive this prompt for a device, drive, or memory card you’re sure you had used with your Mac previously. That’s because of a security footnote: after three days, macOS may decide to prompt you again, under the assumption that if you aren’t using the connected thing continuously, perhaps something has gone amiss with it in the meantime. Is it overkill? I’m sure there’s a reason for the three-day timeout that Apple knows and isn’t disclosing.

If you find these alerts unnecessary and annoying—say, your computer is in your home and nobody but you and trusted family members are ever near it—you can go to  > System Settings > Privacy & Security and set “Allow accessories to connect” to Always or Automatically When Unlocked. Contrariwise, if you want the highest degree of paranoia, set it to Ask Every Time.

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We’ve compiled a list of the questions we get asked most frequently, along with answers and links to columns: read our super FAQ to see if your question is covered. If not, we’re always looking for new problems to solve! Email yours to mac911@macworld.com, including screen captures as appropriate and whether you want your full name used. Not every question will be answered, we don’t reply to email, and we cannot provide direct troubleshooting advice.