Cum facem un Generator de coduri [English]

The first thing to do is to open up Ad Muncher and find out what is going on and how it works. Then load up procdump and dump both the exe and the dll seperately. Look at the size of the exe and the dll, the exe is only a few kbytes, but the dll is much bigger (over a hundred kbytes) and has been packed with UPX. From this we can tell that the dll is the main program and the exe is a loader. Since we are doing this on-the-fly, we wont be needing Win32DASM, but if you do, then you can now disassemble the dumped files

Load up Ad Muncher, enter some bogus information. When you choose what bogus information to include, make sure it DOES NOT contain any characters by choice. This is because it will normally pass most checks on input characteristics. Also, if you were smart enough to actually READ the registration page first, you would have noticed this: 'Please enter your name and code below, the code consists of two hexadecimal numbers (ie: numbers 0-9 and letters A-F) joined with a dash.' Your serial you enter should be something like '012345-543210'. Then set a breakpoint with softice on GetWindowTextA, This means when you Click register, softice should popup. You should be in the middle of a GetDlgItemTextA call, so press F12 twice to return to Ad Muncher. If you didnt break, then you arent using Windows 2000 like i am, and you will have to just set a breakpoint on GetDlgItemTextA directly. Back in the Ad Muncher code, you should see something like this:
00751431 6A68 push 00000068
00751433 FF7508 push [ebp+08]
00751436 E80D0C0000 Call USER32.GetDlgItemTextA
0075143B 40 inc eax
0075143C A33C7A4B00 mov dword ptr [004B7A3C], eax

Disable your breakpoints with 'BD *' and then trace through the code with F10 till you find anything that looks interesting. By the term 'interesting' i mean any use of tables like 'mov ecx, [eax*4+005B8A1C]' or any loops that contain a 'LODSB' or 'LODSW'. Also you may want to look for stuff like 'xor ecx, ecx ; mov eax, [ecx + 005B8A1C] ; inc ecx'. You should come upto this after a minute of searching:
:loop
LODSB
ADD ECX, EAX
ROR ECX, 08
ADD ECX, EBX
CMP AL, 00
JNZ LOOP
NOT ECX

Now if you look at the start of this function and checkout esi you will find that it contatains your username and ebx holds '00012345'. Wow, the first half of our serial and our username Ad Muncher takes your serial, splits it in two, then moves the location of your username into esi, and sets the value of the first half of the serial in ebx. Next it takes a character from esi, starts a running total, rolls the register right 8h times, adds the first half of the serial in ebx to the total and then loops until all of the characters have been read. After this is NOT's the total to give the second half of the serial in ecx. To make a keygen all you have to do now is convert the routine into any language you choose and give it a little interface. You can now use Ad Muncher to create valid serials without any troubles at all, but it is better to have a seperate keygen, so have a go at making one, here is the one I created:
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;Ad Muncher v4.4 Keygen by m101 for Phrozen Crew

.386
.model flat,stdcall
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib

WinMain proto WORD,WORD,WORD,WORD

.data
ClassName db "SimpleWinClass",0
AppName db "Ad Muncher Keygen cracked by m101 for Phrozen Crew",0
ButtonText db "Generate Key",0
StartupString db "Please enter a name...",0
EditClassName db "edit",0
EditID equ 2
EditID2 equ 3
ButtonID equ 1
ButtonClassName db "button",0
IDM_GETTEXT equ 3
Serial2 db "FFFFFFFF"
Serial db "BADC0DE-"
buffer db 512 dup(?)



.data?
hInstance HINSTANCE ?
CommandLine LPSTR ?
hwndButton HWND ?
hwndEdit HWND ?
hwndEdit2 HWND ?
.code
start:
invoke GetModuleHandle, NULL
mov hInstance,eax
invoke GetCommandLine
mov CommandLine,eax
invoke WinMain, hInstance,NULL,CommandLine, SW_SHOWDEFAULT
invoke ExitProcess,eax

WinMain proc hInst:HINSTANCE,hPrevInst:HINSTANCE,CmdLine:LPSTR,CmdShowWORD
LOCAL wc:WNDCLASSEX
LOCAL msg:MSG
LOCAL hwnd:HWND
mov wc.cbSize,SIZEOF WNDCLASSEX
mov wc.style, CS_HREDRAW or CS_VREDRAW
mov wc.lpfnWndProc, OFFSET WndProc
mov wc.cbClsExtra,NULL
mov wc.cbWndExtra,NULL
push hInstance
pop wc.hInstance
mov wc.hbrBackground,COLOR_BTNFACE+1
mov wc.lpszMenuName,NULL
mov wc.lpszClassName,OFFSET ClassName
invoke LoadIcon,NULL,IDI_APPLICATION
mov wc.hIcon,eax
mov wc.hIconSm,eax
invoke LoadCursor,NULL,IDC_ARROW
mov wc.hCursor,eax
invoke RegisterClassEx, addr wc
INVOKE CreateWindowEx,WS_EX_CONTROLPARENT or DS_CENTER,ADDR ClassName,ADDR AppName,\
WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,\
CW_USEDEFAULT,345,150,NULL,NULL,\
hInst,NULL
mov hwnd,eax
invoke ShowWindow, hwnd,SW_SHOWNORMAL
invoke UpdateWindow, hwnd
.WHILE TRUE
invoke GetMessage, ADDR msg,NULL,0,0
.BREAK .IF (!eax)
invoke TranslateMessage, ADDR msg
invoke DispatchMessage, ADDR msg
.ENDW
mov eax,msg.wParam
ret
WinMain endp

WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM
.IF uMsg==WM_DESTROY
invoke PostQuitMessage,NULL
.ELSEIF uMsg==WM_CREATE
invoke CreateWindowEx,WS_EX_CLIENTEDGE, ADDR EditClassName,NULL,\
WS_CHILD or WS_VISIBLE or WS_BORDER or ES_LEFT or\
ES_AUTOHSCROLL,\
50,20,240,25,hWnd,EditID,hInstance,NULL
mov hwndEdit,eax
invoke CreateWindowEx,WS_EX_CLIENTEDGE, ADDR EditClassName,NULL,\
WS_CHILD or WS_VISIBLE or WS_BORDER or ES_LEFT or\
ES_AUTOHSCROLL or ES_READONLY,\
50,45,240,25,hWnd,EditID2,hInstance,NULL
mov hwndEdit2,eax
invoke SetWindowText,hwndEdit2,ADDR StartupString
invoke SetFocus, hwndEdit
invoke CreateWindowEx,NULL, ADDR ButtonClassName,ADDR ButtonText,\
WS_CHILD or WS_VISIBLE or BS_DEFPUSHBUTTON,\
80,75,180,25,hWnd,ButtonID,hInstance,NULL
mov hwndButton,eax
.ELSEIF uMsg==WM_COMMAND
mov eax,wParam
.IF lParam==0
.IF ax==IDM_GETTEXT
push edi
push esi
invoke GetWindowText,hwndEdit,ADDR buffer,512
mov ebx, 0BADC0DEh
lea esi, buffer
xor ecx,ecx

looksy:
lodsb
cmp al, 41h
jl looksy2
cmp al, 5Ah
jg looksy2
add al, 20h
looksy2:
add ecx,eax
ror ecx,08h
add ecx,ebx
cmp al, 0h
jnz looksy
not ecx
mov eax,ecx
mov [Serial2+3h],al
mov [Serial2+2h],ah
shr eax, 10h
mov [Serial2+1h],al
mov [Serial2],ah
lea esi, Serial2
xor ecx,ecx
converter:
xor ax,ax
lodsb
cmp ecx, 8h
jl conv2
xor al, dl
conv2:
shl ax, 4h
shr al, 4h
cmp al, 0ah
jl alpha
add al, 37h
jmp alphanumeric
alpha:
add al, 30h
alphanumeric:
cmp ah, 0ah
jl alphab
add ah, 37h
jmp alphanumericb
alphab:
add ah, 30h
alphanumericb:
mov [buffer+ecx], ah
inc ecx
mov [buffer+ecx], al
inc ecx
cmp ecx, 8h
jl converter
mov [buffer+ecx], 0h
invoke SetWindowText,hwndEdit2,ADDR Serial

pop esi
pop edi
.ELSE
invoke DestroyWindow,hWnd
.ENDIF
.ELSE
.IF ax==ButtonID
shr eax,16
.IF ax==BN_CLICKED
invoke SendMessage,hWnd,WM_COMMAND,IDM_GETTEXT,0
.ENDIF
.ENDIF
.ENDIF
.ELSE
invoke DefWindowProc,hWnd,uMsg,wParam,lParam
ret
.ENDIF
xor eax,eax
ret
WndProc endp
END START