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[分享]FOXIT PDF Editor 2.1去水印
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[分享]FOXIT PDF Editor 2.1去水印
本来水平很菜，高手不要笑话我，发这个帖子一是为了作个记录，二是给和我一样菜的人一起学习，共同进步。不说了，直接发我调试的时候的记录
0040863A |. 68 20C87300 push 0073C820 ; edited by foxit pdf editor
0040863F |. 8D4C24 20 lea ecx, dword ptr [esp+20]
00408643 |. E8 F3F21F00 call 0060793B
00408648 |. 68 64C87300 push 0073C864 ; copyright (c) by foxit software company, 2003 - 2009
0040864D |. 8D4C24 14 lea ecx, dword ptr [esp+14]
00408651 |. 895C24 74 mov dword ptr [esp+74], ebx
00408655 |. E8 E1F21F00 call 0060793B
0040865A |. 68 D0C77300 push 0073C7D0 ; for evaluation only.
-----------------------------------------
上面就是水印了(在字符串中查找上面注释中的字符串，真的找到了)
现在就要想办法不执行上面的这段代码了，在OD窗口中往上找，看有没有 跳转之类的跳过这段代码不执行它
于是找到了这段代码(发现下面的代码中第一行代码就是一个跳转，跳到00408637就完蛋了，就会执行水印的那段代码，那就直接NOP)
00408621 /75 14 jnz short 00408637 ; jnz short 00408637 改为nop
00408623 |. |33C0 xor eax, eax
00408625 |. |5B pop ebx
00408626 |. |8B4C24 58 mov ecx, dword ptr [esp+58]
0040862A |. |64:890D 00000>mov dword ptr fs:[0], ecx
00408631 |. |83C4 64 add esp, 64
00408634 |. |C2 0400 retn 4
有这么一段东西
现在还有一个问题，就是程序启动的时候的提示框，下面把它屏蔽掉
把跳转jnz short 00408637 改为NOP，就会继续执行下面的代码，遇到retn返回了。不会执行到水印的代码里面去
00407521 |. 50 push eax
00407522 |. 51 push ecx
00407523 |. 56 push esi
00407524 |. 52 push edx
00407525 |. 6A 00 push 0
00407527 |. 53 push ebx
00407528 |. 68 A4C67300 push 0073C6A4 ; ASCII "2008/01/19"
0040752D |. 68 A0C67300 push 0073C6A0 ; ASCII "PED"
00407532 |. 57 push edi
00407533 |. E8 B8DD1A00 call 005B52F0
00407538 |. 83C4 24 add esp, 24
0040753B |. 8985 A8040000 mov dword ptr [ebp+4A8], eax
00407541 |. 85C0 test eax, eax
00407543 E9 C0000000 jmp 00407608 ; 这里改一下跳转 原先是jnz 00407608
;为什么会想到这里要跳转呢？原因就是看到下面这段代码的注释中的字符串，在调试的时候改了一下跳转，发现果然好了
00407548 0080 3B00740E add byte ptr [eax+E74003B], al
0040754E |. 6A FF push -1
00407550 |. 6A 00 push 0
00407552 |. 68 92130000 push 1392
00407557 |. E8 7CA12000 call 006116D8
0040755C |> B8 80C67300 mov eax, 0073C680 ; ASCII "Unregistered Retail Customer"
00407561 |> 8A16 /mov dl, byte ptr [esi]
00407563 |. 8A18 |mov bl, byte ptr [eax]
00407565 |. 8ACA |mov cl, dl
00407567 |. 3AD3 |cmp dl, bl
00407569 |. 75 1E |jnz short 00407589
0040756B |. 84C9 |test cl, cl
0040756D |. 74 16 |je short 00407585
0040756F |. 8A56 01 |mov dl, byte ptr [esi+1]
00407572 |. 8A58 01 |mov bl, byte ptr [eax+1]
00407575 |. 8ACA |mov cl, dl
00407577 |. 3AD3 |cmp dl, bl
00407579 |. 75 0E |jnz short 00407589
0040757B |. 83C6 02 |add esi, 2
0040757E |. 83C0 02 |add eax, 2
00407581 |. 84C9 |test cl, cl
00407583 |.^ 75 DC \jnz short 00407561
00407585 |> 33C0 xor eax, eax
00407587 |. EB 05 jmp short 0040758E
00407589 |> 1BC0 sbb eax, eax
0040758B |. 83D8 FF sbb eax, -1
0040758E |> 85C0 test eax, eax
00407590 |. 75 0D jnz short 0040759F
00407592 |. 57 push edi
00407593 |. 8BCD mov ecx, ebp
00407595 |. E8 76030000 call 00407910
0040759A |. E9 F5000000 jmp 00407694
0040759F |> 6A 00 push 0
004075A1 |. 8D4C24 14 lea ecx, dword ptr [esp+14]
004075A5 |. E8 E6700100 call 0041E690
004075AA |. 8D4C24 10 lea ecx, dword ptr [esp+10]
004075AE |. C78424 E00200>mov dword ptr [esp+2E0], 0
004075B9 |. E8 7DF31F00 call 0060693B
004075BE |. 8D4C24 74 lea ecx, dword ptr [esp+74]
004075C2 |. C78424 E00200>mov dword ptr [esp+2E0], 3
004075CD |. E8 FB022000 call 006078CD
004075D2 |. 8D4C24 70 lea ecx, dword ptr [esp+70]
004075D6 |. C68424 E00200>mov byte ptr [esp+2E0], 2
004075DE |. E8 EA022000 call 006078CD
004075E3 |. 8D4C24 6C lea ecx, dword ptr [esp+6C]
004075E7 |. C68424 E00200>mov byte ptr [esp+2E0], 1
004075EF |. E8 D9022000 call 006078CD
004075F4 |. C78424 E00200>mov dword ptr [esp+2E0], -1
004075FF |. 8D4C24 10 lea ecx, dword ptr [esp+10]
00407603 |. E9 87000000 jmp 0040768F
00407608 |> B8 80C67300 mov eax, 0073C680 ; ASCII "Unregistered Retail Customer"
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