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Grub4DosBootmgr


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#1 LostNspace

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Posted 2 weeks ago

I posted this earlier in the wrong section.

 

Has anyone been able to hex edit the newer bootmgr from Win 10 1803 in Grub4dos? If so, what version?

 

 

 

Example:

 

This worked fine on the earlier versions of the Win 10 bootmgr but doesn't work using the bootmgr from 1803

set Boot=(rd)+1
map --mem %USBDrive%/bootmgr (rd)
cat --hex --locate=\x74\x3\xE9\x8\x0\x39\x56 --replace=\xEB\x8\xE9\x8\x0\x39\x56 (rd)+1
cat --hex --skip=0x48000 --length=0x18000 --number=1 --locate=C\x00D --replace=C\x003 (rd)+1


#2 steve6375

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Posted 2 weeks ago

The first line seems to work (in that the string is found)

but the second line which replaces the string BCD with BC3 does not work because 'BCD' does not appear to be in bootmgr any more!

I cannot find C\x00D in the whole file.

In fact, I cannot find it in a Win8 bootmgr version either, but it is in a Win7 version of bootmgr.

 

Are you sure it worked fine in earlier Win10 versions?



#3 steve6375

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Posted 2 weeks ago

See https://msfn.org/boa...tmgr-windows-8/

If you modified bootmgr using this tool and then compared the two versions, you could work out what bytes need to be changed and then change them using grub4dos in memory?

https://msfn.org/boa...tmgr-windows-8/

 

Tool here

https://msfn.org/boa...comment=1110495



#4 LostNspace

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Posted 2 weeks ago

The first line seems to work (in that the string is found)

but the second line which replaces the string BCD with BC3 does not work because 'BCD' does not appear to be in bootmgr any more!

I cannot find C\x00D in the whole file.

In fact, I cannot find it in a Win8 bootmgr version either, but it is in a Win7 version of bootmgr.

 

Are you sure it worked fine in earlier Win10 versions?

 

steve6375, thank you for the reply. I apologize, it is a Win 7 bootmgr I am using that the above string works on. That Win 7 bootmgr will boot my newly created WinPE I made out of 10 1803 source  but looks kinda weird on the screen doing so. I was hoping to use the 1803 bootmgr. It's not an extremely big deal, but was just curious if maybe the older Grub4DoS  I'm using is the issue or the new bootmgr.



#5 steve6375

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Posted 2 weeks ago

Using the tool you could make different versions of bootmgr - e.g. bootmgr10BCC, bootmgr10BCE, etc.

 

  1. Download and run BMplus v1.3.4 https://www.usbtor.r...topic.php?t=562
  2. Run it and set radio button to Win10
  3. drag-and-drop bootmgr  (win10 version) onto the form.
  4. change 'Path to BCD' menu to  \BOOT\BCC
  5. click on Make BOOTMGR button to save in BM.Builds folder as bootmgr10
  6. rename bootmgr10 to bootmgr10BCC

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#6 LostNspace

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Posted 2 weeks ago

 

Using the tool you could make different versions of bootmgr - e.g. bootmgr10BCC, bootmgr10BCE, etc.

 

  1. Download and run BMplus v1.3.4 https://www.usbtor.r...topic.php?t=562
  2. Set radio button to Win10
  3. run it and drag-and-drop bootmgr  (win10 version) onto the form.
  4. change 'Path to BCD' menu to  \BOOT\BCC
  5. click on Make BOOTMGR button to save in BM.Builds folder as bootmgr10
  6. rename bootmgr10 to bootmgr10BCC

 

 

Thank you, steve6375!

 

Funny that you posted that link because I was in the process of asking you did you know of an English version to conty9's BCDtool and the BMplus v1.3.4 tool after I found the site from the link you posted earlier. I've been clicking on file open tabs for over 20 years so I can do so by memory on the BCDtool that is in Russian, but would like to see to see the text in English if it were possible. No big deal if not tho.






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