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I plug in a USB stick with Mojave macos installer. When I boot with Option key hold down, USB is not listed.

I have tried different DMG images and different USB drives.

Previously I erased macbook HDD (it has Linux only now) and flashed EFI partition with Refind. Consequently, Cmd+R recovery mode is not accessible anymore on my Macbook Pro 2017.

In this case, it seems that only two options left:

  1. Use bless , which is only present on macos and requires physical USB stick not DMG/iso image.
  2. Recovery mode where you can configure drive to become bootable or at least check why it is not

Are there any other options? I seem to be left locked out because my USB stick with installer is not listed there.

MarkTa
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  • Could you be a bit clearer? This post seems like a rant. What is the question? – David Anderson Mar 20 '20 at 01:16
  • Actually it is not all that clear, and has been flagged as such. – IconDaemon Mar 20 '20 at 01:22
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    What makes you think you erased the firmware? Your question shows no evidence of this. Erasing the HDD does not erase the firmware. The firmware is not stored on the HDD. The installation of rEFInd does not change the firmware. – David Anderson Mar 20 '20 at 01:22
  • I did it with my hands by installing Refind, erasing macos partition and thus erasing macos recovery. EFI partition is only firmware I am aware of on Intel macs. There is only internet recovery which is not what most people need to install specific MacOS they need in secure way. – MarkTa Mar 20 '20 at 01:26
  • Again, the firmware is not stored on the HDD. The firmware is stored on the logic board. So what do you mean by firmware? – David Anderson Mar 20 '20 at 01:28
  • Recovery mode with terminal and csrutil as example is indeed firmware I erased. I can boot to Linux, but I have no recovery as it was stored on that partition I call firmware which is gone. With recovery mode I could do almost anything. Yes, you erase recovery by erasing HDD and recovery is indeed fits firmware definition. Most people don't notice this as they don't erase macos. – MarkTa Mar 20 '20 at 01:29
  • I have no idea how is that go so unnoticed by people that recovery mode seems to be stored on HDD. Whatever it is ESP, EFi or etc, I probably erased it – MarkTa Mar 20 '20 at 01:36
  • OK, so what do you want to fix? Do you want to reinstall macOS. You can do this using macOS Recovery over the Internet. You can use a flash drive, if you have another Mac to create the flash drive. This also depends the model of the other Mac and the version of macOS installed. – David Anderson Mar 20 '20 at 01:45
  • If use thebless command to instruction the firmware to boot from a device such as a flash drive, then the bless command writes nothing to this flash drive. In such cases, the bless command writes to memory on the logic board. – David Anderson Mar 20 '20 at 01:51
  • David, I updated my question to make it more specific. Unfortunately internet recovery is not an option for most cases. Especially when your network performs malicious mitm attacks and you are traveling – MarkTa Mar 20 '20 at 01:56
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    You can not get a mitm attack using Internet Recovery unless the certificates in the firmware have been compromised and that is highly unlikely. To create a Mojave USB installer, you would have first download Mojave. What makes this download any safer than downloading Mojave while booted from Internet Recovery? – David Anderson Mar 20 '20 at 02:13
  • Is there any proof of a certificate check in the process? One can ensure TLS is involved by looking at ports in traffic, but testing SSL pinning and validation is another thing. I will definitely check this later, currently, I am trying TransMac to create USB stick. What makes image files safer is that you can always explore their contents before use and they are the version you need. Internet recovery can also contain code execution vulnerability. Bios level malware is extremely trendy and proprietary systems being researched for years. – MarkTa Mar 20 '20 at 02:23
  • That last comment made me chuckle... you’re more concerned with a compromise of your firmware and indirectly, the Apple servers that host the net boot image than you are of that Transmac software? How much did you post for it again and tell me how much exploring your going to do versus a built on hash check? – Allan Mar 20 '20 at 15:23

1 Answers1

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If you have properly created a Mojave USB flash driver installer, inserted the flash drive in a USB port on the Mac and booted to the Startup Manger, then the an icon will appear representing the flash drive. If this does not happen, then either the flash drive was not plugged directly into the Mac or the flash drive was not properly created. In other words, most likely there is something wrong with the DMG image or something wrong with the way you transferred to the flash drive.

As for the two options:

  1. Use bless , which is only present on macos and requires physical USB stick not DMG/iso image.

    The bless could could be used to avoid using the Startup Manager. However, a properly created Mojave USB flash drive installer would appear in the Startup Manager. Besides, you have no way to execute the bless command.

  2. Recovery mode where you can configure drive to become bootable or at least check why it is not.

    You have erased the any recover volumes that may have existed on your Mac. The only ways left to boot to Recover mode would be from an external drive or the internet. So far you have stated you can not boot from any external sources. In the comments, you have stated that you are to afraid to use the internet.

A good reference on how to install macOS can be found as the accepted answer to the question: How can I download an older version of OS X/macOS?

David Anderson
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