What follows is an extreme scenario, simply to better understand the extension of Time Machine's utility.

Let's assume that up to this moment our system is fully backed up via TM and is not infected.

Now, if we intentionally infect it with a file we know is a virus and let it spread, can we simply just use TM to revert to the last backup before infection and guarantee there are no traces of the virus?

Yes, no, or it depends?

On a more realistic approach, what I wish to accomplish, is test several new apps I have never used before. Some of them might be closed source and/or sketchy. I was thinking, I could install them, test them and after I'm done, either keep them or just simply rollback via TM. Would that work, or would traces of those apps be left behind?

1 Answer 1


If things are sketchy, what prevents them from infecting your TM history as well?

More secure options

  • Test things within a VM (ideally without shared drives etc).
  • Make a full-image backup of your Mac, make sure you can restore it and then unplug the backup drive from your Mac. Once done with the tests, wipe your Mac and restore the backup.
  • Get a separate Mac for tests
  • 1
    Just to add on here - taking an external (not local snapshot) time machine backup then unplugging the disk would meet the second item here
    – Ezekiel
    Jun 30, 2021 at 16:28
  • @nohillside Was suspecting that might be the case, which is why I asked here to be sure. Ok, the 3rd option will cost. About the 1st one, is a VM completely sandboxed from the host OS? Also, can I mirror the host OS into the virtual one (by using TM maybe?) Then, instead of the 2nd one, I'm guessing it's ok if I use a partition of my Mac's HD, to restore a TM backup, tryout all the apps I need to, and after I'm done erase it with Disk Utility, right? (While I've booted from this "trial partition", my main partition on my HD will not be mounted of course) Jun 30, 2021 at 19:56
  • @miraqolo6689 1) Theoretically yes. 2) Depends on which risks you want to protect against. A rogue application can still format the whole HD for instance.
    – nohillside
    Jun 30, 2021 at 20:44

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