DS
Junior
 Inregistrat: acum 17 ani
Postari: 38
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I used the following tools : SoftIce 3.01, W32Dasm 8.9, Notepad (word wrap on) - and my brain  .
For all who don't like code snippets in there tutorials - my apologies right now - cause the following text contains quite a lot of it. Another thing, due to all the code we have to trace to get to the complete "create_good_serial" construction I won't explain the code in detail, I'll just explain it where I think it's necessary and I tell you what the result is of the code.
So let's get to work! Load the target, and load SoftIce (SI). Press "Agree_and_Register" button.
Fill out the 3 information fields, I used the following information,
Name : Vizion
Company : MeX/C4N
Serial : 12121212
Get in SI and set a breakpoint on GetDlgItem, get out SI. Press "Ok" button.
This should bring you back in SI, press F11 and you should see the following piece of code (*),
* Reference To: USER32.GetDlgItem, Ord:00F3h
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:0040246A 8B3D6C144200 mov edi, dword ptr [0042146C] <--- load GetDlgItem in edi
:00402470 8D8518FFFFFF lea eax, dword ptr [ebp+FFFFFF18]
:00402476 50 push eax
:00402477 6A64 push 00000064
:00402479 6A0D push 0000000D
:0040247B 6813040000 push 00000413
:00402480 53 push ebx
:00402481 FFD7 call edi <--- read user name
* Reference To: USER32.SendMessageA, Ord:01DAh
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:00402483 8B3568144200 mov esi, dword ptr [00421468] <--- you should be here (*)
:00402489 50 push eax
:0040248A FFD6 call esi
:0040248C 8D4580 lea eax, dword ptr [ebp-80]
:0040248F 50 push eax
:00402490 6A64 push 00000064
:00402492 6A0D push 0000000D
:00402494 680F040000 push 0000040F
:00402499 53 push ebx
:0040249A FFD7 call edi <--- read company name
:0040249C 50 push eax
:0040249D FFD6 call esi
:0040249F 8D45E8 lea eax, dword ptr [ebp-18]
:004024A2 50 push eax
:004024A3 6A14 push 00000014
:004024A5 6A0D push 0000000D
:004024A7 6814040000 push 00000414
:004024AC 53 push ebx
:004024AD FFD7 call edi <--- read serial number
:004024AF 50 push eax
:004024B0 FFD6 call esi
:004024B2 8D45E8 lea eax, dword ptr [ebp-18] <--- addr : entered serial
:004024B5 50 push eax
:004024B6 8D4580 lea eax, dword ptr [ebp-80] <--- addr : company
:004024B9 50 push eax
:004024BA 8D8518FFFFFF lea eax, dword ptr [ebp+FFFFFF18] <--- addr : name
:004024C0 50 push eax
:004024C1 E886000000 call 0040254C <--- here_it_happens
:004024C6 83C40C add esp, 0000000C
:004024C9 85C0 test eax, eax <--- is entered serial ok
:004024CB 7D15 jge 004024E2 <--- yes? jmp_good_buyer
:004024CD 6A30 push 00000030
...
I suggest, that you check the lines at 004024B2, 004024B6 and 004024BA in SI, just use "db eax". You should see the information you entered. So if you like to crack/patch this target I suggest you read the tutorial by bulll. Let's take a look at the call to 400254C (trace this call in SI),
* Referenced by a CALL at Address:
|:004024C1
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:0040254C 55 push ebp
:0040254D 8BEC mov ebp, esp
:0040254F 83EC18 sub esp, 00000018
:00402552 8D45E8 lea eax, dword ptr [ebp-18]
:00402555 50 push eax
:00402556 FF750C push [ebp+0C]
:00402559 FF7508 push [ebp+08]
:0040255C E8D7020000 call 00402838 <--- calculate_good_serial
:00402561 83C40C add esp, 0000000C
:00402564 8D45E8 lea eax, dword ptr [ebp-18]
:00402567 FF7510 push [ebp+10]
:0040256A 50 push eax
:0040256B E8605F0000 call 004084D0 <--- compare_entered_good_serial
:00402570 59 pop ecx
:00402571 F7D8 neg eax
:00402573 59 pop ecx
:00402574 1BC0 sbb eax, eax
:00402576 C9 leave
:00402577 C3 ret
...
What you want me to explain on the above code - get in "calculate_good_serial" call - we should see the following code,
* Referenced by a CALL at Addresses:
|:0040255C , :004026F6
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:00402838 55 push ebp
:00402839 8BEC mov ebp, esp
:0040283B 81ECEC000000 sub esp, 000000EC
:00402841 56 push esi
:00402842 57 push edi
:00402843 FF7508 push [ebp+08]
:0040255C E8D7020000 call 00402838
:00402846 8D8514FFFFFF lea eax, dword ptr [ebp+FFFFFF14]
:0040284C 50 push eax
:0040284D E87E5D0000 call 004085D0 <--- (1)
:00402852 59 pop ecx
:00402853 8D8514FFFFFF lea eax, dword ptr [ebp+FFFFFF14]
:00402859 59 pop ecx
:0040285A FF750C push [ebp+0C]
:0040285D 50 push eax
:0040285E E87D5D0000 call 004085E0 <--- (2)
:00402863 59 pop ecx
:00402864 8D8514FFFFFF lea eax, dword ptr [ebp+FFFFFF14]
:0040286A 59 pop ecx
* Possible StringData Ref from Data Obj ->"SweetHeart" <--- sweet_str
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:0040286B 68147C4100 push 00417C14
:00402870 50 push eax
:00402871 E86A5D0000 call 004085E0 <--- (3)
:00402876 59 pop ecx
:00402877 8D4508 lea eax, dword ptr [ebp+08]
:0040287A 59 pop ecx
:0040287B 50 push eax
:0040287C 8D8514FFFFFF lea eax, dword ptr [ebp+FFFFFF14]
:00402882 50 push eax
:00402883 E8A8590000 call 00408230 <--- (4)
:00402888 59 pop ecx
:00402889 8D45E8 lea eax, dword ptr [ebp-18]
:0040288C 59 pop ecx
:0040288D FF7508 push [ebp+08]
...
Ok, after calls (1), (2) and (3) we've got the following string in memory : VizionMeX/C4NSweetHeart - you should be able to recognize the following parts : <name><company><sweet_str>. Call (4) will calculate the serial from the string mentioned above, so lets take a look at call (4),
* Referenced by a CALL at Address:
|:00402883
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:00408230 8B542404 mov edx, dword ptr [esp+04]
:00408234 56 push esi
:00408235 33F6 xor esi, esi <--- esi = 0
:00408237 803A00 cmp byte ptr [edx], 00
:0040823A 7423 je 0040825F
* Referenced by a (U)nconditional or (C)onditional Jump at Address:
|:0040825D(C)
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:0040823C C1E604 shl esi, 04 <--- start creating serial
:0040823F 42 inc edx
:00408240 0FBE42FF movsx eax, byte ptr [edx-01]
:00408244 03F0 add esi, eax
:00408246 8BC6 mov eax, esi
:00408248 25000000F0 and eax, F0000000
:0040824D 7407 je 00408256
:0040824F 8BC8 mov ecx, eax
:00408251 C1E918 shr ecx, 18
:00408254 33F1 xor esi, ecx
* Referenced by a (U)nconditional or (C)onditional Jump at Address:
|:0040824D(C)
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:00408256 F7D0 not eax
:00408258 23F0 and esi, eax
:0040825A 803A00 cmp byte ptr [edx], 00 <--- end of string?
:0040825D 75DD jne 0040823C <--- no, go on with creation
* Referenced by a (U)nconditional or (C)onditional Jump at Address:
|:0040823A(C)
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:0040825F 8B44240C mov eax, dword ptr [esp+0C]
:00408263 6A00 push 00000000
:00408265 8930 mov dword ptr [eax], esi
:00408267 E814000000 call 00408280 <--- not important
:0040826C 83C404 add esp, 00000004
:0040826F 33C0 xor eax, eax
:00408271 5E pop esi
:00408272 C3 ret
After the calculation of code lines 0040823C to 0040825D we got the following serial number : 211003668.
You can try this number - just like I did - but it won't work. So exit the call, we're back at 00402888 (see above). Here is the code that follows after call (4), this part of the serial creation consist of 6 parts -OR- 6 calls. I just tell you what they do, if you like to take a closer look at them go ahead,
* Possible StringData Ref from Data Obj ->"%u"
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:00402890 6828724100 push 00417228
:00402895 50 push eax
:00402896 E8C55C0000 call 00408560 <--- number to string conversion
:0040289B 83C40C add esp, 0000000C
:0040289E 8D45E8 lea eax, dword ptr [ebp-18]
* Possible Reference to String Resource ID=00001: "Welcome to AxMan v2.11 (Official Release). You..."
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:004028A1 6A01 push 00000001
:004028A3 6A09 push 00000009
:004028A5 6A30 push 00000030
:004028A7 50 push eax
:004028A8 E853540000 call 00407D00 <--- not important (I think
:004028AD 8B7510 mov esi, dword ptr [ebp+10]
:004028B0 83C410 add esp, 00000010
:004028B3 8D45E8 lea eax, dword ptr [ebp-18]
* Possible Reference to String Resource ID=00003: "DFEND CORP DISCLAIMS ALL WARRANTIES RELATING TO..."
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:004028B6 6A03 push 00000003
:004028B8 50 push eax
:004028B9 56 push esi
:004028BA E861600000 call 00408920 <--- 1st part : xxx
:004028BF 80660300 and byte ptr [esi+03], 00
:004028C3 83C40C add esp, 0000000C
* Possible StringData Ref from Data Obj ->"-" <--- ! VERY interesting !
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:004028C6 BF107C4100 mov edi, 00417C10
:004028CB 57 push edi
:004028CC 56 push esi
:004028CD E80E5D0000 call 004085E0 <--- adds "-" : xxx-
:004028D2 59 pop ecx
:004028D3 8D45EB lea eax, dword ptr [ebp-15]
:004028D6 59 pop ecx
* Possible Reference to String Resource ID=00003: "DFEND CORP DISCLAIMS ALL WARRANTIES RELATING TO..."
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:004028D7 6A03 push 00000003
:004028D9 50 push eax
:004028DA 56 push esi
:004028DB E8906D0000 call 00409670 <--- 2nd part : xxx-xxx
:004028E0 80660700 and byte ptr [esi+07], 00
:004028E4 83C40C add esp, 0000000C
:004028E7 57 push edi
:004028E8 56 push esi
:004028E9 E8F25C0000 call 004085E0 <--- adds "-" : xxx-xxx-
:004028EE 59 pop ecx
:004028EF 8D45EE lea eax, dword ptr [ebp-12]
:004028F2 59 pop ecx
* Possible Reference to String Resource ID=00003: "DFEND CORP DISCLAIMS ALL WARRANTIES RELATING TO..."
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:004028F3 6A03 push 00000003
:004028F5 50 push eax
:004028F6 56 push esi
:004028F7 E8746D0000 call 00409670 <--- 3rd part : xxx-xxx-xxx
:004028FC 83C40C add esp, 0000000C
:004028FF 80660B00 and byte ptr [esi+0B], 00
:00402903 5F pop edi
:00402904 5E pop esi
:00402905 C9 leave
:00402906 C3 ret
So, now we got the following serial in memory : 211-003-668. This time it works! When we leave this call, we arrive back at 00402561 (see above), what follows is a simple string compare in call 004084D0.
Well now we got the complete solution to our "create_good_serial" construction, here follows a piece of code in Turbo Pascal 7.0 - ofcourse you could write this in C, ASM (if you're suicidal or any language you like most (this code is not a perfect solution, just a quick example),
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program AxMan;
const
sweet : string[10] = 'SweetHeart';
var
uname,
ucomp : string;
unaml : byte absolute uname;
ucoml : byte absolute ucomp;
i, { edx }
j : byte;
dumm0, { esi }
dumm1, { eax }
dumm2 : longint; { ecx }
result,
temp : string;
templ : byte absolute temp;
begin
writeln('AxMan v2.11 - Key Generator by Vizion [MeX/C4N]');
write('Enter Name : ');
readln(uname);
write('Enter Company : ');
readln(ucomp);
uname := uname + ucomp + sweet;
for i := 1 to unaml do
begin
dumm0 := dumm0 shl $4;
dumm0 := dumm0 + byte(uname[i]);
dumm1 := dumm0;
dumm1 := dumm1 and $F0000000;
if (dumm1 <> 0)
then begin
dumm2 := dumm1 shr $18;
dumm0 := dumm0 xor dumm2
end;
dumm0 := dumm0 and (not dumm1)
end;
Str(dumm0, temp);
j := 1;
for i := 1 to templ do
begin
if i in [4,7]
then begin
result[j] := '-';
Inc(j);
result[j] := temp[i];
end
else result[j] := temp[i];
Inc(j)
end;
result[0] := #11;
write('Registration key : ', result)
end.
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If there is someone, who can do this key generator in assembly, please tell me and show me the source code. Would be very appreciated! I could use some teaching in assembly programming.
So, that's all folks, I hope you enjoyed this "little" tutorial,
13.9KB
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Only One Road!
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