I have a Mid 2009 MacBook Pro that was used by a "less than responsible" user. As such, it seems to have become infected with malware that rewrites all SSL certificates. These certificates cannot be validated by OS X which is what alerted me to the fact that there is a problem.

My issue is that I cannot access the App Store to initiate a reinstallation of OS X. Since the MacBook Pro can't validate the App Store SSL certificates, nothing loads.

So, I'm stuck. What steps should I take to reinstall OS X or restore access to the App Store?

Update: Cmd + R on boot doesn't seem to work (perhaps due to the Malware). Also, the OS version is 10.9.5 (Mavericks).

  • Do you have another mac from with you can copy the installer over? Also try booting in Safe Mode (hold shift during startup, booting might take longer) – GeF Nov 17 '15 at 21:54
  • Great suggestion! I'm actually already giving that a shot right now! :) I'm attempting to create bootable media for El Capitan. Will update here with the results. – rinogo Nov 17 '15 at 21:56
  • I guess this is how Apple forces you to install newer OS -- they make AppStore tell you some bs about "item" just ti make you install Captain. – Nakilon Aug 1 '16 at 21:26

use Cmd + Option + R to go into internet recovery then follow these steps https://support.apple.com/en-nz/HT201314

  • Welcome to Ask Different! Please edit your answer to include the actual steps. We generally frown on link-only answers because if the page gets taken down for any reason, the answer becomes useless. – user24601 Nov 18 '15 at 3:21
  • Thanks! Can someone who has this problem verify that this works? If so, I might change the accepted answer to this one. – rinogo Aug 1 '16 at 21:23
  • On a separate occasion, I've verified that this works. Since I believe this is a better option for most users, I'm changing this to the accepted answer. – rinogo Oct 21 '16 at 20:34

I've solved the problem!

Like I said, for some reason, I couldn't get the recovery mode to work (Cmd + R). Nor could I connect to the app store to (re)download the OS.

I did, however, have another Mac. SO, I used the other system to download El Capitan, install it to a flash drive, which I used to wipe the "problem" system and reinstall the OS.

I followed these instructions: https://support.apple.com/en-us/HT201372

Two important steps:

  1. My first attempt failed because my flash drive wasn't partitioned with the "GUID" partition table option. Re-partitioning with this option enabled fixed the problem.
  2. In order to completely eradicate the malware, I formatted the internal drive before installing the OS (to ensure that a completely fresh install was performed instead of merely an upgrade).

Everything is working great! Hopefully something here helps someone else out there. Thanks everyone for your input!

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