flat assembler
Message board for the users of flat assembler.

Home Search Register
Log in to check your private messages Log in

Index > Windows > How to unassemble function in WinDbg?
Author
Thread Post new topic Reply to topic
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 08:21
Further discussion from https://board.flatassembler.net/topic.php?p=244745#244745 ,
here is the new topic for it.

Core i7 wrote:
..yes, in WinDBG you only need to open *.exe files
For your i.exe, pdb is not necessary - symbols are needed for system libraries. What OS and version of WindBG do you have?
Open exe and press "g" to load all the dlls of your application. After that, request information about any dll, for example kernel32 - get information about symbols:
Code:
0:000:x86> !lmi kernel32        ;<---------
Loaded Module Info: [kernel32] 
         Module:  kernel32
   Base Address:  0000000076990000
     Image Name:  C:\Windows\syswow64\kernel32.dll
   Machine Type:  332 (I386)
     Time Stamp:  66f77b38 Sat Sep 28 08:42:48 2024
           Size:  110000
       CheckSum:  11549b
Characteristics:  2102  perf
Debug Data Dirs:  Type  Size     VA  Pointer
              CODEVIEW    26, d0e50,   d0e50 RSDS - GUID: {EC4B15F0-9D87-42A0-BDD2-FBA9BE736232}
                Age: 2, Pdb: wkernel32.pdb
                 CLSID     4, d0e4c,   d0e4c [Data not mapped]
     Image Type: FILE     - Image read successfully from debugger.
                 C:\Windows\syswow64\kernel32.dll
    Symbol Type: PDB      - Symbols loaded successfully from symbol server.
                 c:\symbols\wkernel32.pdb\EC4B15F09D8742A0BDD2FBA9BE7362322\wkernel32.pdb   ;<---------------
    Load Report: private symbols , not source indexed 
                 c:\symbols\wkernel32.pdb\EC4B15F09D8742A0BDD2FBA9BE7362322\wkernel32.pdb


Win10 22H2, WinDbg 10.0.22621.3233 X86.

The "!lmi kernel32" displays successfully.

And I got these folders in C:\Symbols:
Code:
 Volume in drive C has no label.
 Volume Serial Number is C2E5-895D

 Directory of C:\Symbols

20/06/2025  03:12 PM    <DIR>          .
20/06/2025  03:12 PM    <DIR>          ..
20/06/2025  03:12 PM    <DIR>          msvcp_win.pdb
20/06/2025  03:09 PM                 0 pingme.txt
20/06/2025  03:12 PM    <DIR>          ucrtbase.pdb
20/06/2025  03:12 PM    <DIR>          wgdi32.pdb
20/06/2025  03:12 PM    <DIR>          wgdi32full.pdb
20/06/2025  03:12 PM    <DIR>          wkernel32.pdb
20/06/2025  03:12 PM    <DIR>          wkernelbase.pdb
20/06/2025  03:09 PM    <DIR>          wntdll.pdb
20/06/2025  03:12 PM    <DIR>          wuser32.pdb
20/06/2025  03:12 PM    <DIR>          wwin32u.pdb


But "uf GetTickCount" still doesn't work. Same error.
Post 20 Jun 2025, 08:21
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 08:24
Core i7 wrote:

....
2. Run WinDBG and press [Ctrl+S] - see the menu
3. In the window that appears, specify the server for downloading symbols to your folder: srv*c:\Symbols*https://msdl.microsoft.com/download/symbols
4. Save the settings and restart the debugger.


Do I need to repeat the steps above every time I start the WinDbg, because every time I starts it is "Server path: srv*".
Post 20 Jun 2025, 08:24
View user's profile Send private message Reply with quote
Core i7



Joined: 14 Nov 2024
Posts: 111
Location: Socket on motherboard
Core i7 20 Jun 2025, 08:46
No, you don't need to repeat it - this is only for the first time.
Well, there seem to be symbols for standard dll User/Kernel32.
Maybe you're entering the name incorrectly?
Code:
0:000> g                  ;<---- Run debug

0:000> bp @$exentry       ;<---- Set BP on EntryPoint

0:000:x86> g              ;<---- Run debug

Breakpoint 0 hit
image00000000_00400000+0x5000:
00405000 ff1564714000    call    dword ptr [image00000000_00400000+0x7164 (00407164)] ds:002b:00407164={shell32!IsUserAnAdmin (75ae445d)}

0:000:x86> x kernel32!*GetTickCount*      ;<----- Find API in library

769a111c  kernel32!GetTickCountStub      = <no type information>
769a0c40  kernel32!_imp__GetTickCount    = <no type information>
769bd72f  kernel32!GetTickCount64Stub    = <no type information>
769a0c00  kernel32!_imp__GetTickCount64  = <no type information>
769bd736  kernel32!GetTickCount64        = <no type information>
769a1123  kernel32!GetTickCount          = <no type information>

0:000:x86> uf GetTickCount64              ;<----- Unassemble
KERNELBASE!GetTickCount64:
750f906d eb02            jmp     KERNELBASE!GetTickCount64+0x4 (750f9071)

KERNELBASE!GetTickCount64+0x2:
750f906f f390            pause

KERNELBASE!GetTickCount64+0x4:
750f9071 8b0d2403fe7f    mov     ecx,dword ptr [SharedUserData+0x324 (7ffe0324)]
750f9077 8b152003fe7f    mov     edx,dword ptr [SharedUserData+0x320 (7ffe0320)]
750f907d a12803fe7f      mov     eax,dword ptr [SharedUserData+0x328 (7ffe0328)]
750f9082 3bc8            cmp     ecx,eax
750f9084 75e9            jne     KERNELBASE!GetTickCount64+0x2 (750f906f)

KERNELBASE!GetTickCount64+0x19:
750f9086 a10400fe7f      mov     eax,dword ptr [SharedUserData+0x4 (7ffe0004)]
750f908b f7e2            mul     eax,edx
750f908d 0facd018        shrd    eax,edx,18h
750f9091 56              push    esi
750f9092 57              push    edi
750f9093 c1ea18          shr     edx,18h
750f9096 8bf0            mov     esi,eax
750f9098 a10400fe7f      mov     eax,dword ptr [SharedUserData+0x4 (7ffe0004)]
750f909d 8bfa            mov     edi,edx
750f909f f7e1            mul     eax,ecx
750f90a1 6a00            push    0
750f90a3 6800010000      push    100h
750f90a8 52              push    edx
750f90a9 50              push    eax
750f90aa e80be50200      call    KERNELBASE!_allmul (751275ba)
750f90af 03f0            add     esi,eax
750f90b1 13fa            adc     edi,edx
750f90b3 8bd7            mov     edx,edi
750f90b5 5f              pop     edi
750f90b6 8bc6            mov     eax,esi
750f90b8 5e              pop     esi
750f90b9 c3              ret
Post 20 Jun 2025, 08:46
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:02
Thanks for helping me so far, I almost giving up.

I got "No runnable debuggees error in 'g'" even if I set the breakpoint to entrypoint or 0x401000 (in i.exe).

The "x" command seems work, but "uf" doesn't work.


Description:
Filesize: 27.68 KB
Viewed: 674 Time(s)

i.PNG

Post 20 Jun 2025, 09:02
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:12
Actually I used your "bp @$exentry", also same, "g" can run for the first time only.

Code:
0:000> g
ModLoad: 75790000 757b5000   C:\Windows\SysWOW64\IMM32.DLL
ModLoad: 747d0000 74844000   C:\Windows\SysWOW64\uxtheme.dll
ModLoad: 75820000 758df000   C:\Windows\SysWOW64\msvcrt.dll
ModLoad: 75b80000 75e00000   C:\Windows\SysWOW64\combase.dll
ModLoad: 76310000 763cc000   C:\Windows\SysWOW64\RPCRT4.dll
ModLoad: 76700000 767d4000   C:\Windows\SysWOW64\MSCTF.dll
ModLoad: 765d0000 76666000   C:\Windows\SysWOW64\OLEAUT32.dll
ModLoad: 75e00000 75e77000   C:\Windows\SysWOW64\sechost.dll
ModLoad: 76270000 76289000   C:\Windows\SysWOW64\bcrypt.dll
ModLoad: 74850000 7485f000   C:\Windows\SysWOW64\kernel.appcore.dll
ModLoad: 75a20000 75a7f000   C:\Windows\SysWOW64\bcryptPrimitives.dll
ModLoad: 743c0000 74479000   C:\Windows\SysWOW64\textinputframework.dll
ModLoad: 74140000 743bf000   C:\Windows\SysWOW64\CoreUIComponents.dll
ModLoad: 74070000 74099000   C:\Windows\SysWOW64\ntmarta.dll
ModLoad: 76670000 766f7000   C:\Windows\SysWOW64\SHCORE.dll
ModLoad: 76290000 7630d000   C:\Windows\SysWOW64\advapi32.dll
ModLoad: 740a0000 7413b000   C:\Windows\SysWOW64\CoreMessaging.dll
ModLoad: 761f0000 76253000   C:\Windows\SysWOW64\WS2_32.dll
ModLoad: 73f90000 7406d000   C:\Windows\SysWOW64\wintypes.dll
ModLoad: 74480000 74515000   C:\Windows\SysWOW64\TextShaping.dll
ModLoad: 760e0000 761c3000   C:\Windows\SysWOW64\ole32.dll
eax=00000000 ebx=00000000 ecx=00000000 edx=00000000 esi=00000000 edi=77665b40
eip=775b34ac esp=000dfe7c ebp=000dff54 iopl=0         nv up ei pl nz na po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00000202
ntdll!NtTerminateProcess+0xc:
775b34ac c20800          ret     8
0:000> g
       ^ No runnable debuggees error in 'g'
0:000> g
       ^ No runnable debuggees error in 'g'
0:000> bp @$exentry
0:000> g
       ^ No runnable debuggees error in 'g'
Post 20 Jun 2025, 09:12
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:20
But this works:

Code:
0:000> uf GetTickCount64Kernel32
KERNEL32!GetTickCount64Kernel32:
75aacc60 8bff            mov     edi,edi
75aacc62 55              push    ebp
75aacc63 8bec            mov     ebp,esp
75aacc65 51              push    ecx
75aacc66 53              push    ebx
75aacc67 56              push    esi
75aacc68 57              push    edi
75aacc69 8b3d0400fe7f    mov     edi,dword ptr [SharedUserData+0x4 (7ffe0004)]
75aacc6f ba2403fe7f      mov     edx,offset SharedUserData+0x324 (7ffe0324)
75aacc74 897dfc          mov     dword ptr [ebp-4],edi
75aacc77 be2003fe7f      mov     esi,offset SharedUserData!SystemCallStub+0x20 (7ffe0320)
75aacc7c bf2803fe7f      mov     edi,offset SharedUserData+0x328 (7ffe0328)

KERNEL32!GetTickCount64Kernel32+0x21:
75aacc81 8b02            mov     eax,dword ptr [edx]
75aacc83 8b1e            mov     ebx,dword ptr [esi]
75aacc85 8b0f            mov     ecx,dword ptr [edi]
75aacc87 3bc1            cmp     eax,ecx
75aacc89 7525            jne     KERNEL32!GetTickCount64Kernel32+0x50 (75aaccb0)  Branch

KERNEL32!GetTickCount64Kernel32+0x2b:
75aacc8b f765fc          mul     eax,dword ptr [ebp-4]
75aacc8e 5f              pop     edi
75aacc8f 8bc8            mov     ecx,eax
75aacc91 8bf2            mov     esi,edx
75aacc93 8bc3            mov     eax,ebx
75aacc95 f765fc          mul     eax,dword ptr [ebp-4]
75aacc98 0fa4ce08        shld    esi,ecx,8
75aacc9c 0facd018        shrd    eax,edx,18h
75aacca0 c1e108          shl     ecx,8
75aacca3 c1ea18          shr     edx,18h
75aacca6 03c1            add     eax,ecx
75aacca8 13d6            adc     edx,esi
75aaccaa 5e              pop     esi
75aaccab 5b              pop     ebx
75aaccac 8be5            mov     esp,ebp
75aaccae 5d              pop     ebp
75aaccaf c3              ret

KERNEL32!GetTickCount64Kernel32+0x50:
75aaccb0 f390            pause
75aaccb2 ebcd            jmp     KERNEL32!GetTickCount64Kernel32+0x21 (75aacc81)  Branch


Strange, it is different name.
Post 20 Jun 2025, 09:20
View user's profile Send private message Reply with quote
Core i7



Joined: 14 Nov 2024
Posts: 111
Location: Socket on motherboard
Core i7 20 Jun 2025, 09:23
try this guide, will there be errors or not.
https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/getting-started-with-windbg
Post 20 Jun 2025, 09:23
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:33
Core i7 wrote:
try this guide, will there be errors or not.
https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/getting-started-with-windbg


Thanks once again for your help so far, I think I will just stop here.

The "uf" is working for "ReadFile" and "GetStdHandle", just that for GetTickCount, I must enter "uf /i GetTickCount64Kernel32".

Only one Google search result returned for "GetTickCount64Kernel32", I mean the whole Internet don't document this anywhere.
Post 20 Jun 2025, 09:33
View user's profile Send private message Reply with quote
revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 20689
Location: In your JS exploiting you and your system
revolution 20 Jun 2025, 09:37
The public API name is GetTickCount. All the other names are internal functions. Those names can/will/do change for different versions of Windows. Don't reply on them. Using non-public APIs is fraught with problems.
Post 20 Jun 2025, 09:37
View user's profile Send private message Visit poster's website Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:41
Thank you @Core i7, now I can unassemble function of Win32 API by first using "x" to examine the symbols.

Nice to read Win32 API function code....
Post 20 Jun 2025, 09:41
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 09:42
revolution wrote:
The public API name is GetTickCount. All the other names are internal functions. Those names can/will/do change for different versions of Windows. Don't rely on them. Using non-public APIs is fraught with problems.


Thanks for your reminder., @revolution... Still wonder why no "GetTickCount" in my WinDbg session when examining symbols ("x" command).
Post 20 Jun 2025, 09:42
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 10:12
Good news! Now works, in both x86 and x64.


Description: x86
Filesize: 33.92 KB
Viewed: 625 Time(s)

86.PNG

Description: x64
Filesize: 34.03 KB
Viewed: 629 Time(s)

64.PNG



Last edited by Mat Qua sar on 20 Jun 2025, 10:16; edited 1 time in total
Post 20 Jun 2025, 10:12
View user's profile Send private message Reply with quote
Core i7



Joined: 14 Nov 2024
Posts: 111
Location: Socket on motherboard
Core i7 20 Jun 2025, 10:15
For "uf" there are 2 useful keys - this is /i (instruction counter), and /c (only call).
The latter helps to determine the nesting of calls, for example:
Code:
0:000:x86> uf /i /c CreateFileA
         KERNELBASE!CreateFileA (7510c90b), 30 instructions    ;<---------

  KERNELBASE!CreateFileA+0xe (7510c919):
    call to KERNELBASE!Basep8BitStringToDynamicUnicodeString (75127cbf)

  KERNELBASE!CreateFileA+0x32 (7510c93d):
    call to KERNELBASE!CreateFileW       (7510c470)

  KERNELBASE!CreateFileA+0x3d (7510c948):
    call to ntdll32!RtlFreeAnsiString    (76ebe266)
Post 20 Jun 2025, 10:15
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 10:17
Noted with thanks.
Post 20 Jun 2025, 10:17
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 20 Jun 2025, 10:23
Let me summarize how to unassemble Win32 API function.

(Build symbols first, as suggested by @Core i7, then the below follows....)
1) Open an executable
2) Run "g"
3) Type "x kernel32!" (or "x user32!")
4) Type "uf XXXXXX" , with XXXXX being the kernel32 API function you want
Post 20 Jun 2025, 10:23
View user's profile Send private message Reply with quote
a



Joined: 10 Apr 2025
Posts: 29
Location: Ukraine
a 21 Jun 2025, 08:20
Mat, how many accounts do you have?
Post 21 Jun 2025, 08:20
View user's profile Send private message Reply with quote
Mat Qua sar



Joined: 13 Jun 2025
Posts: 35
Mat Qua sar 21 Jun 2025, 09:34
a wrote:
Mat, how many accounts do you have?


That's terrific (except last one, Quasar is not me) Embarassed

This is due to some said I have account deletion OCD, sort of mental hygiene.
I am sorry if that disrupts the forum's operation and leaving lasting impression on members' mental notes. This also happens in at least other two forums I joined.

But there is more to just Mat*Quasar*, when I first joined, I used FlierMate, there are many variations in user name surrounding F?ier*Mate* too.
Post 21 Jun 2025, 09:34
View user's profile Send private message Reply with quote
a



Joined: 10 Apr 2025
Posts: 29
Location: Ukraine
a 21 Jun 2025, 16:18
Apperantly thoose 2 pages show the same user
https://board.flatassembler.net/search.php?search_author=Mat%20Quasar
https://board.flatassembler.net/search.php?search_author=Mat+Quasar

And Mat_Quasar doesn't exist, it just shows those 2 different users:
- Mat+Quasar
- Mat-Quasar
https://board.flatassembler.net/search.php?search_author=Mat_Quasar
Post 21 Jun 2025, 16:18
View user's profile Send private message Reply with quote
a



Joined: 10 Apr 2025
Posts: 29
Location: Ukraine
a 21 Jun 2025, 16:18
Here is the complete list:


I have successfuly wasted my time

If you got any more usernames tell me, I collect those.
will exchange this one with anyone for a legendary https://board.flatassembler.net/search.php?search_author=FlierMate11
this one is a rare edition: https://board.flatassembler.net/search.php?search_author=FIierMate
I will sell it for 50$
Post 21 Jun 2025, 16:18
View user's profile Send private message Reply with quote
a



Joined: 10 Apr 2025
Posts: 29
Location: Ukraine
a 22 Jun 2025, 12:43
Mat Qua sar wrote:

That's terrific (except last one, Quasar is not me)

This is due to some said I have account deletion OCD, sort of mental hygiene.
I am sorry if that disrupts the forum's operation and leaving lasting impression on members' mental notes. This also happens in at least other two forums I joined.

But there is more to just Mat*Quasar*, when I first joined, I used FlierMate, there are many variations in user name surrounding F?ier*Mate* too.
I have something similiar where if I haven't used account in a year then I would just create a new one. And I also don't like the fact that people can view my post history, but what you gonna do.


Also, I made a browser bookmark that logins you automatically, you just click on it.
    1. Create New Bookmark
    2. Paste this text into URL feild :
Code:
javascript:A=document.querySelectorAll("[name=username],[name=password],[name=login]");A[0].value="PUT_USERNAME_HERE";A[1].value="PUT_PASSWORD_HERE";A[2].click()
    3. Replace text "PUT_USERNAME_HERE" with your username
    4. Replace text "PUT_PASSWORD_HERE" with password
    5. Save
    6. Click the Bookmark to run the script

I use it all the time Wink
If anyone wants me to create a chrome / firefox extension where you have to press a key instead, then ask me (it wont have any spyware)
Post 22 Jun 2025, 12:43
View user's profile Send private message Reply with quote
Display posts from previous:
Post new topic Reply to topic

Jump to:  


< Last Thread | Next Thread >
Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Main index Download Documentation Examples Message board

Copyright © 1999-2025, Tomasz Grysztar. Also on GitHub, YouTube.

Website powered by rwasa.