VERY IMPORTANT: macOS Installer.app file and file contents permissions

[mitchellkza]

I thought I would post this here as it is actually very important for anyone creating OSX installers using just about any method and can drive you mad chasing all sorts of crazy install errors, kernel panics and reboots.

 

I had a problem recently where the same steps I had followed for doing well over 70+ installations without any problems suddenly just stopped working.

 

Nothing had changed (or so I thought) and what started happening for the first time ever during my first boot after installation was macOS Sierra crashing and rebooting due to a kernelcache missing error being preceded also by many kext-dev-mode errors due to invalid signatures on all the kext files.

 

Googling that error for hours and hours revealed no results or solutions that helped me. I eventually realized what the culprit may be and decided to see if I was right and indeed I was.

 

I had moved my Install macOS Sierra.app (10.12.1) file from my Applications folder to another hard drive on my system in order to be able to download the 10.12.2 installer. 

 

What happened when I moved the installer to my other drive is that the installer took on the permissions of the drive I moved it to. In this case I moved it to one of my Data drives which had permissions set as me being the recursive owner across all files, folders, subfolders, files AND their contents.

 

What happened when I moved the 10.12.1 installer back to Applications is that I could create my Clover installer using U******T but I would suddenly get all these strange errors which I had never had before.

 

I deleted the installer and grabbed a fresh one from the App Store and I could then finally confirm 100% that file permissions had been modified extensively on my installer and this was obviously causing all kexts to be seen as unsigned.

 

So in case anyone runs into strange errors, always make sure you have a clean installer downloaded only from the App Store and if you ever move it to another drive in order to be able to download a newer one, make sure you reset the permissions on it before you create an installer with it.

 

The two screen grabs below will show you how my faulty installer's permissions looked and how a cleanly downloaded installer's permissions should look.

 

In terminal your file permissions for an installer from the App Store should be `drxwr-xr-x 3 root wheel`

 

So if you are creating bootable installers and getting all sorts of strange errors, your installer.app's permissions may be messed.