Theoretical question about OS upgrades and infections

Discussion in 'Mac Basics and Help' started by Redvaleshia, Jan 20, 2017.

  1. Redvaleshia, Jan 20, 2017
    Last edited: Jan 20, 2017

    Redvaleshia macrumors newbie

    Jan 20, 2017
    I read that Mac has nasties that can't run in newer OS.

    1) If OS is infected and new OS is patched against such infections or safe against them, will upgrading to new OS override those infections in old OS and... delete them? Seal them away? Keep the there, but harmless?

    Or will infections in old OS corrupt something during upgrade and infections stay active even when it looks like new OS was successfully installed?

    2) And could infections in OS overall mess something up during OS upgrade and make it weak, cause security holes?
  2. keysofanxiety macrumors G3


    Nov 23, 2011
    Practically the only infections you'll encounter on a Mac would be malware. All the system files in the newer OS iterations are completely locked down with System Integrity Protection anyway. An OS update will just patch system files and a few other bits and bobs (for instance, update Safari/Mail or other Mac apps).

    The worst you'll get are a few popups and maybe MacKeeper finding its way to the Applications folder, which can be quickly solved with a quick blast through MalwareBytes for Mac:

    Remember that the absolute best virus protection is the squishy thing using the computer (that's you, unless you're made of granite or something). Stay vigilant, practice safe browsing habits, and don't download or run anything you're not familar with.
  3. Redvaleshia thread starter macrumors newbie

    Jan 20, 2017
    Thank you for answer!

    1) So OS upgrade would not suppress or remove if there is any malware or such in old OS?
    2) If anything might be there in old OS, it will come to new OS, but won't ruin anything during installation?
    3) Malwarebytes will find anything harmful there is for Mac?

    My question was more about technical curiosity as I'm more used to Windows. :D
  4. keysofanxiety macrumors G3


    Nov 23, 2011
    1) Correct, but any infections on the system aren't going to really do any damage anyway. The exception to this rule is if Apple remove known malware with an update (for instance, with the Flashback malware).

    2) Correct, no way it will affect installation.

    3) Pretty much. If there's anything that MalwareBytes misses, there are other ways to remove. However there are limited points of infection on a Mac, so 99/100 MWB finds anything malicious, or they will update their definitions in a future update to grab anything that may have been missed. That's why you'll find MWB will take about 1 minute to scan on a Mac, whereas it can take hours on a Windows machine :D
  5. Redvaleshia thread starter macrumors newbie

    Jan 20, 2017
    Thank you for all the help! :D

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