Accessing the user folder from a previous Windows installation (content on a read-only image)

Question

Before upgrading from Windows 7 to Windows 10 I imaged the Windows 7 system using O&O DiskImage Professional. After a clean upgrade (wiped the original installation) I started restoring content, and eventually came across something I had forgotten to pull from my old personal folder before reinstall. To my surprise I couldn't access the \Users\MyOldFolder on the image, apparently because its Admin and user UUIDs were now different. As an admin on a new install I would normally just assume ownership of the old content and would be good to go, but the image is read-only so I can't alter the permissions on it.

My question is: Is there any way to access that content – i.e. as an admin of the Windows 10 Pro installation make Windows to ignore the offending old permissions? Or is my only option to write the image onto a disk so that I can modify the permissions as needed? I tried to turn UAC off but that did not make a difference.

Answer 1

I'm answering my own question that I had already written, but hadn't yet posted by the time I came across the answer. There was a ~duplicate (How to gain access to Windows Users folders on a read-only backup medium), but its answer did not help because turning UAC off made no difference in my case.

There was a solution, however:

1. Download and install SysInternals Suite (specifically PsExec, which is part of the suite).

2. Start PowerShell with elevated privileges.

3. If SysInternals suite (and specifically PsExec.exe) isn't on the path, navigate to the folder you installed it in.

4. Now execute cmd as SYSTEM:
   psexec -s cmd.exe

5. You're now able to access the content whose Administrator and USER UUIDs have changed due to the system reinstall (but which you can't modify because of the read-only media). You're now accessing it as the SYSTEM which does not change from install to install.
   
   Simply navigate to the mounted read-only media, and walk right in to the folder you were previously denied access to, like R:\Users\MyOldFolder (a user folder of the old Windows installation).
   
   You can then copy files out. I used xxcopy to copy my entire old profile folder from the read-only media into a folder on my hard drive so that I can easily retrieve missing program config files as I configure my new Windows 10 installation. 2022 update: xxcopy was discontinued a few years ago, but you can use instead Windows' built-in robocopy to accomplish the same, like so: robocopy c:/path/to/source d:/path/to/target *.* /COPY:D, where D implies "Data only" (and no attributes, or the owner), as outlined in this superuser.com thread.

I found the critical details for the above from a TechNet thread.