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congnt92

Need Help! Modify bootmgr windows 8

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Hi all

I want to modify bootmgr windows 8 where value bcd change to bc1, bc2... How can I do it?

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You will need bmzip and PEChecksum by Jeffrey Bush

First decompress bootmgr

bmzip bootmgr bootmgr.exe

Joakim has found out how to Modify bootmgr of Windows 8

Here you have the adresses for bootmgr.exe version 6.2.9200.16384 (RTM)

So use a HexEditor and change following bytes in bootmgr.exe.

0000066B: 0F 90
0000066C: 88 90
0000066D: A3 90
0000066E: 02 90
0000066F: 00 90
00000670: 00 90

0002957A: 74 EB

000295A1: 75 EB

At adress 8345C you have the \Boot\BCD string that you can change.

Then use PEChecksum to update the Exe checksum

PEChecksum bootmgr.exe

And Finally recompress bootmgr

bmzip /c bootmgr.exe bootmgr

bootmgr-tools.zip

Edited by JFX
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thanks JFX. I hex edit successed. God bless you :angel :angel :angel But after modified bootmgr, when I boot setup windows 8, prompt stopped about 5 seconds. Then the installation can be continue. How do I fix it ?

Capture-3.png

Edited by congnt92
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Are you sure that delay comes from bootmgr?

It boots instantly for me!

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I'm sure. Because if I use bootmgr original, no matter what happend. You can send me your bootmgr file after modified?

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Might be better to post yours so we can see what you did wrong, and suggest ways so you can do it correctly next time.

Cheers and Regards

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Might be better to post yours so we can see what you did wrong, and suggest ways so you can do it correctly next time.

It might be even better if noone re-distributes non-redistributable files through the board.

Noone ever heard of hashing a file (let's say MD5) to check if it's the same as another one? :unsure:

jaclaz

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Thanks all. Here my bootmgr after modify. I don't know what did I do wrong ?

Bootmgr.rar

Edited by congnt92
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@congnt92

You did nothing wrong, you edit it correctly.

But still i can't reproduce your problem.

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thanks JFX. Now, I think I should be content with what I already have because the error does not affect the installation process. Thanks again, JFX.

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Here you have the addresses for bootmgr.exe version 6.3.9600.16384 (RTM)

0000065E: 0F 900000065F: 88 9000000660: AE 9000000661: 02 9000000662: 00 9000000663: 00 900002B1C1: 74 EB0002B1EB: 75 EB

At address 8AF90 you have the \Boot\BCD string that you can change.

@Mods

Maybe this topic would be better places in WinPE or Multi boot sub forum.

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Just wanted to thank JFX :thumbup for providing a working compiled bmzip.exe and clear, easy to follow, instructions on it's use.  :)

 

It took me some (too much :() time to FAIL :w00t::ph34r: in replicating with the tools provided directly or indirectly here:

http://reboot.pro/topic/16915-bootmgr-recompiler/

and all of 3 (three) minutes to succeed   :yes: with the version of the tool JFX provided.

 

 

jaclaz

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JFYI, instead of PEChecksum.exe one can also use Unsigntool.

It strips the no longer needed digital signature and fixes the PE Header checksum.

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So for everyone how doesn't like command line or hex editing, I've updated my old zbootmgr tool.

 

http://1drv.ms/1plzVcu

Edited by JFX
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So for everyone how doesn't like command line or hex editing, I've updated my old zbootmgr tool.

 

http://1drv.ms/1plzVcu

 

Thanks for sharing :)

But I don't know why running this tool for modity bootmgr windows 8.1, I get "Unsupported OS, newer ntdll.dll needed!" error

 

 

Here you have the addresses for bootmgr.exe version 6.3.9600.16384 (RTM)

0000065E: 0F 90

0000065F: 88 90

00000660: AE 90

00000661: 02 90

00000662: 00 90

00000663: 00 90

0002B1C1: 74 EB

0002B1EB: 75 EB          At address 8AF90 you have the \Boot\BCD string that you can change.

 

With bootmgr windows 8.1 update (6.3.9600.16415). At address 0000065E: is 01 not 0F. Can I change it to 90 ?

And now, Windows 10 was came. I can't modify bootmgr windows 10 by this way.

Can you update the method to modify bootmgr windows 8.1 update and bootmgr windows 10?

Thanks

Edited by congnt92
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"Unsupported OS, newer ntdll.dll needed!"

 
Means your running this tool not under Windows 8, and your ntdll.dll has not the functions to decompress and recompress bootmgr.
You can put ntdll.dll from a win8 install next to the program an try again.
 
If the offset has changed, then please don't change these bytes.
If I have some time I take  a look at the new version.
But seriously you don't need a win10 bootmgr, do you?
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But seriously you don't need a win10 bootmgr, do you?

 

Did you actually mean "But seriously you don't need a win10, do you?" :unsure:

 

;)

 

jaclaz

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"Unsupported OS, newer ntdll.dll needed!"

 
Means your running this tool not under Windows 8, and your ntdll.dll has not the functions to decompress and recompress bootmgr.
You can put ntdll.dll from a win8 install next to the program an try again.

 

 

I run this tool under windows 8.1 spring update. Version Bootmgr in windows 8.1 spring update is 6.3.9600.16415 not 6.3.9600.16384. May this is reason why i get that error.

 

 

If the offset has changed, then please don't change these bytes.

 

As you say, in ver 6.3.9600.16415, We only need to change \Boot\BCD to custom value. What about these

 

0000065E: 0F 90

0000065F: 88 90

00000660: AE 90

00000661: 02 90

00000662: 00 90

00000663: 00 90

0002B1C1: 74 EB

0002B1EB: 75 EB

 

 

Thanks

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But seriously you don't need a win10 bootmgr, do you?

 

Did you actually mean "But seriously you don't need a win10, do you?" :unsure:

 

;)

 

jaclaz

 

 

Same question with you! And still wating for the answers :D

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congnt92, please re-download and try again.

 

http://1drv.ms/1plzVcu

 

Thanks. I run it under windows 8.1 update 1 and windows 10 technical preview. It work fine on windows 8.1 update 1. It does not support for win 10.

And I still have a question.

- If we modify bootmgr manally (decompress, hex edit, checksum, recompress), the size of bootmgr (after modified) less original bootmgr about 3kb.

- If using your tool, bootmgr after modified is same size with original bootmgr.

Could you tell me why?

And it would be greater if your tool allow user create modified bootmgr with "ABC" string instead "BC0, BC1, ..." :D

And your tool work fine but I want to learn how to manually modified bootmgr as you guide me at #3 (decompress, hex edit, recompress ...). Can you guide me?

And thanks again, JFX.

Edited by congnt92
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Yeah, better let's wait for Win10 final  ;)

 

Well, bmzip.exe does compress better, so the new bootmgr will be slighlty smaller.

I use the same compression code MS uses, so the size will stay more or less equal.

 
Maybe next year I'll add "ABC" feature.

 

This should be the offsets for 6.3.9600.16415

0000CF0E: 0F 900000CF0F: 88 900000CF10: AE 900000CF11: 02 900000CF12: 00 900000CF13: 00 90000194A9: 74 EB000194D3: 75 EB          At address D84 you have the \Boot\BCD string that you can change.
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