一次逆向fb寻找密码的记录及还原相关算法

  一次逆向fb寻找密码的记录及还原相关算法

  注册游戏账号◀◀◀点击图片进入游戏————◀◀◀◀———点击图片进入游戏———真钱棋牌游戏,棋牌游戏,棋牌文化

  首先用peid查壳。



一个ASProtect v1.23RC1 *的壳,然后我到网上搜了下有没有相关的脱壳教程,在这里发现了一篇https://bbs.pediy.com/thread-207728.htm 但是他的脱壳方法有些麻烦,而且很多步骤都没有说明原因,只能自己脱了,首先用od载入程序,单步了几下,发现一个pushad

然后用esp定律,f9 断在这个地方

接着单步几下,发现没有oep特征,由此可知这个加了几层壳,继续单步,发现单步很久都没发现啥,如果你有耐心,会发现到后面还会出现几次pushad ,大概要单步几千次吧,,于是我又用了几次esp定律,继续单步,发现这玩意一直带着我在几个函数之间转圈圈,,我当时调这个应该是调了一天,,这么一直转下去不是办法,只能用点特殊的办法,让他帮我们还原到最接近oep的地方,我对esp有特征的下硬件断点,然后记录f9的次数,和啥时候该下断点,

这是当时调试记录的笔记=-=。

倒数第四行那里我发现,f9 71次时代码已经被还原。

于是就从70次开始单步,本来以为离oep已经很近了的,结果一单步下来又是几千条指令,单步了几个小时还是没发现oep。

指令还是在几个函数间转圈圈,本来我打算继续用之前的办法再缩小到oep的距离的。

可这样下去不是办法,于是,尝试直接f9,从堆栈中倒着来找oep,选了几个堆栈返回地址,

在这个地址往上翻了翻就翻到了oep。



一个典型的vc++的oep,然后开始脱壳分析。

用od载入脱完壳的程序。

搜索所有字符串

看见了这几个网址,点进去,再用ida打开,找到相关函数f5。


signed int __thiscall sub_406540(void *this, int a2)

  {

   int v2; // ebx@1

   int v3; // esi@1

   int v4; // ebp@2

   int v5; // edx@2

   const char **v6; // edi@3

   int v7; // ebp@11

   const char **v8; // edi@12

   int v9; // edx@17

   DWORD v10; // eax@20

   const char *v11; // eax@21

   bool v12; // bl@22

   bool v13; // bl@23

   int v14; // ebp@26

   int v15; // edx@26

   const char **v16; // edi@27

   wchar_t *v18; // eax@54

   const char *v19; // eax@56

   bool v20; // bl@57

   bool v21; // bl@58

   int v22; // ebp@61

   int v23; // edx@61

   const char **v24; // edi@62

   const char *v25; // [sp+28h] [bp-C74h]@1

   int i; // [sp+2Ch] [bp-C70h]@1

   LPVOID ppv; // [sp+30h] [bp-C6Ch]@1

   DWORD dwIndex; // [sp+34h] [bp-C68h]@3

   int v29; // [sp+38h] [bp-C64h]@1

   DWORD cchValueName; // [sp+3Ch] [bp-C60h]@1

   DWORD cbData; // [sp+40h] [bp-C5Ch]@12

   char v32; // [sp+44h] [bp-C58h]@1

   int v33; // [sp+48h] [bp-C54h]@3

   int v34; // [sp+4Ch] [bp-C50h]@1

   int v35; // [sp+58h] [bp-C44h]@23

   int v36; // [sp+5Ch] [bp-C40h]@21

   HKEY phkResult; // [sp+60h] [bp-C3Ch]@18

   int v38; // [sp+64h] [bp-C38h]@52

   char v39; // [sp+68h] [bp-C34h]@52

   LPCWSTR lpWideCharStr; // [sp+6Ch] [bp-C30h]@54

   CHAR ValueName; // [sp+90h] [bp-C0Ch]@20

   BYTE Data; // [sp+490h] [bp-80Ch]@20

   int v43; // [sp+C98h] [bp-4h]@1

   cchValueName = (DWORD)this;

   v25 = (const char *)dword_5FAB30;

   v43 = 0;

   v29 = 0;

   ppv = 0;

   LOBYTE(v43) = 2;

   sub_5810E6(&v32);

   LOBYTE(v43) = 3;

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://www.facebook.com");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://www.facebook.com/");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "https://login.facebook.com");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "https://login.facebook.com/");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://www.facebook.com/login.php");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://www.facebook.com/index.php");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "https://www.google.com/accounts/servicelogin");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "https://www.regnow.com/vendorpriv/");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "https://www.regnow.com/affiliatepriv/");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://127.0.0.1/phpmyadmin/");

   CStringArray::SetAtGrow((CStringArray *)&v32, v34, "http://www.yandex.ru/");

   v2 = a2;

   v3 = 0;

   for ( i = 0; v3 < v34; i = v3 )

   {

   v4 = *(_DWORD *)(v2 + 8);

   v5 = 0;

   if ( v4 > 0 )

   {

   v6 = *(const char ***)(v2 + 4);

   dwIndex = *(_DWORD *)(v33 + 4 * v3);

   do

   {

   if ( !strcmp((const char *)dwIndex, *v6) )

   break;

   ++v5;

   ++v6;

   }

   while ( v5 < v4 );

   v3 = i;

   v2 = a2;

   }

   if ( v5 == v4 )

   sub_581340(v2, v4, v33 + 4 * v3);

   ++v3;

   }

   i = 0;

   if ( *(_DWORD *)(cchValueName + 8) > 0 )

   {

   do

   {

   v7 = *(_DWORD *)(v2 + 8);

   dwIndex = 0;

   if ( v7 > 0 )

   {

   v8 = *(const char ***)(v2 + 4);

   cbData = *(_DWORD *)(*(_DWORD *)(cchValueName + 4) + 4 * i);

   do

   {

   if ( !strcmp((const char *)cbData, *v8) )

   break;

   ++v8;

   ++dwIndex;

   }

   while ( (signed int)dwIndex < v7 );

   }

   if ( dwIndex == v7 )

   sub_581340(v2, v7, *(_DWORD *)(cchValueName + 4) + 4 * i);

   v9 = *(_DWORD *)(cchValueName + 8);

   ++i;

   }

   while ( i < v9 );

   }

   if ( !RegOpenKeyExA(HKEY_CURRENT_USER, "Software\\Microsoft\\Internet Explorer\\TypedURLs", 0, 1u, &phkResult) )// 打开注册表

   {

   dwIndex = 0;

   while ( 1 )

   {

   v10 = dwIndex++;

   Data = 0;

   ValueName = 0;

   cbData = 2048;

   cchValueName = 1024;

   if ( RegEnumValueA(phkResult, v10, &ValueName, &cchValueName, 0, 0, &Data, &cbData) )// 遍历注册表,第一个参数是打开的注册表句柄,第二个参数是遍历的index,第三个参数是接收注册表键名的缓冲区,第四个参数指定第三个缓冲区的大小,倒数第二个是键值的缓冲区,最后一个参数指定前一个的大小

   break;

   CString::operator=((CString *)&v25, (char *)&Data);// 把键值赋值给v25

   v11 = *(const char **)sub_57F15A(&v25, (int)&v36, 4u);

   LOBYTE(v43) = 4;

   if ( !strcmp(v11, "http")

   (v12 = strcmp(*(const char **)sub_57F15A(&v25, (int)&i, 3u), (const char *)&dword_5F882C) == 0,

   sub_58643C(&i),

   v12)

   (v13 = strcmp(*(const char **)sub_57F15A(&v25, (int)&v35, 3u), (const char *)&off_5F8828) == 0,

   sub_58643C(&v35),

   v13) )

   {

   v13 = 1;

   }

   LOBYTE(v43) = 3;

   sub_58643C(&v36);

   if ( v13 )

   {

   v14 = 0;

   v15 = *(_DWORD *)(a2 + 8);

   if ( v15 > 0 )

   {

   v16 = *(const char ***)(a2 + 4);

   do

   {

   if ( !strcmp(v25, *v16) ) // 如果键值和a2偏移4的那个变量不相等,则跳出循环

   break;

   ++v14;

   ++v16; // 跟下一条字符串进行比较

   }

   while ( v14 < v15 );

   }

   if ( v14 == v15 ) // 若没找到fb官网的键值

   sub_581340(a2, v15, (int)&v25); // 调用这个函数

   }

   }

   RegCloseKey(phkResult);

   }

   if ( ppv )

   (*(void (__stdcall **)(LPVOID))(*(_DWORD *)ppv + 8))(ppv);// 释放对象

   ppv = 0;

   if ( CoCreateInstance(&rclsid, 0, 1u, &riid, &ppv) < 0 )// 创建一个com对象

   {

   LOBYTE(v43) = 2;

   CStringArray::~CStringArray((CStringArray *)&v32);

   LOBYTE(v43) = 1;

   if ( ppv )

   (*(void (__stdcall **)(LPVOID))(*(_DWORD *)ppv + 8))(ppv);// 释放对象

   LOBYTE(v43) = 0;

   if ( v29 )

   (*(void (__stdcall **)(int))(*(_DWORD *)v29 + 8))(v29);

  LABEL_49:

   v43 = -1;

   sub_58643C(&v25);

   return 0;

   }

   if ( v29 )

   (*(void (__stdcall **)(int))(*(_DWORD *)v29 + 8))(v29);

   v29 = 0;

   if ( !ppv )

   sub_449BF9(-2147467261);

   if ( (*(int (__stdcall **)(LPVOID, int *))(*(_DWORD *)ppv + 28))(ppv, &v29) < 0 )// 调用进程中的某个方法,得到一个新的函数地址

   {

   LOBYTE(v43) = 2;

   CStringArray::~CStringArray((CStringArray *)&v32);

   LOBYTE(v43) = 1;

   if ( ppv )

   (*(void (__stdcall **)(LPVOID))(*(_DWORD *)ppv + 8))(ppv);// 释放对象

   LOBYTE(v43) = 0;

   if ( v29 )

   (*(void (__stdcall **)(int))(*(_DWORD *)v29 + 8))(v29);

   goto LABEL_49;

   }

   while ( 1 )

   {

   if ( !v29 )

   sub_449BF9(-2147467261);

   if ( (*(int (__stdcall **)(int, signed int, char *, int *))(*(_DWORD *)v29 + 12))(v29, 1, &v39, &v38) < 0 !v38 )// 得到ie最近的历史记录,

   break;

   v18 = wcschr(lpWideCharStr, 0x3Fu);

   if ( v18 )

   *v18 = 0;

   CString::operator=((CString *)&v25, lpWideCharStr);

   v19 = *(const char **)sub_57F15A(&v25, (int)&cbData, 4u);

   LOBYTE(v43) = 5;

   if ( !strcmp(v19, "http")

   (v20 = strcmp(*(const char **)sub_57F15A(&v25, (int)&v36, 3u), (const char *)&dword_5F882C) == 0,

   sub_58643C(&v36),

   v20)

   (v21 = strcmp(*(const char **)sub_57F15A(&v25, (int)&v35, 3u), (const char *)&off_5F8828) == 0,

   sub_58643C(&v35),

   v21) )

   {

   v21 = 1;

   }

   LOBYTE(v43) = 3;

   sub_58643C(&cbData);

   if ( v21 )

   {

   v22 = 0;

   v23 = *(_DWORD *)(a2 + 8);

   if ( v23 > 0 ) // 遍历他,对比程序前面的几个http链接

   {

   v24 = *(const char ***)(a2 + 4);

   do

   {

   if ( !strcmp(*v24, v25) )

   break;

   ++v22;

   ++v24;

   }

   while ( v22 < v23 );

   }

   if ( v22 == v23 )

   sub_581340(a2, v23, (int)&v25);

   }

   }

   LOBYTE(v43) = 2;

   CStringArray::~CStringArray((CStringArray *)&v32);

   LOBYTE(v43) = 1;

   if ( ppv )

   (*(void (__stdcall **)(LPVOID))(*(_DWORD *)ppv + 8))(ppv);

   LOBYTE(v43) = 0;

   if ( v29 )

   (*(void (__stdcall **)(int))(*(_DWORD *)v29 + 8))(v29);

   v43 = -1;

   sub_58643C(&v25);

   return 1;

  }
分析之后我们发现他是从注册表的

这个注册表里存着的是ie收藏的url。



查找比对url,然后再调用ieframe.dll里面的某个函数来获取历史记录,至于是什么函数目前我还没办法知道。

ida也分析不出来..可能只能去调那个dll?看功能来分析?不过我后来获取了一下ieframe的导出表。

查看了一下导出函数,想到可能可以从基址偏移来看调用的是哪个函数。

他调用那个函数取出来的也是一些url。

是ie的历史url缓存,这个函数大概的意思就是把url都取出来然后push到一个类似vector的结构里面存着。

解密的关键并不在这里。

在字符串搜索里我们还看见了一串注册表的位置,

打开相应位置看看,

发现是一些加密数据,可能关键就在这里了,往下翻,发现调用了这个函数

具体代码请自行分析,跟进

继续跟进,

发现在这个函数里调用了关键函数,

CryptUnprotectData,其中第一个参数是加密数据的结构体,图中a2便是加密数据的地址,a3是加密时的附加嫡,为url的登陆链接的字节码,解密完了的数据在pDataout结构体里,用od调试看看,

这个是最后那个解密完数据存放的地址,

解密之前,

解密之后,前四个字节是此解密数据的大小,后四个字节是解密数据的地址,

大概就是这些数据了,我们可以很明显的看到在最后面存放着我们需要的密码,test123,密码是我自己测试设置的,
然后此函数处理这些解密数据,得到密码

跟进

#define _CRT_SECURE_NO_WARNINGS

  #pragma comment(lib,"Crypt32.lib")

  #include <Windows.h>

  #include <dpapi.h>

  #include <iostream>

  #include <cwchar>

  #include <atlstr.h>

  unsigned int convert(int* a1, unsigned int a5);

  int main() {

   DATA_BLOB DataIn;

   std::cout << sizeof(DATA_BLOB) << std::endl;

   DATA_BLOB DataOut;

   DATA_BLOB pOptionalEntropy;

   char dest[100] = {0};

   BYTE bpkey[310]

   {

   0x01,0x00,0x00,0x00,0xD0,0x8C,0x9D,0xDF,0x01,0x15,0xD1,0x11,0x8C,0x7A,0x00,0xC0,

   0x4F,0xC2,0x97,0xEB,0x01,0x00,0x00,0x00,0xC0,0x6E,0xDE,0xB1,0x74,0x52,0xCB,0x46,

   0x9F,0xF5,0x92,0x73,0x39,0x9D,0x52,0x72,0x00,0x00,0x00,0x00,0x02,0x00,0x00,0x00,

   0x00,0x00,0x10,0x66,0x00,0x00,0x00,0x01,0x00,0x00,0x20,0x00,0x00,0x00,0x03,0x9F,

   0x65,0xE0,0x95,0xEC,0x94,0xE1,0x55,0x78,0x8D,0x0F,0x7F,0xF6,0x79,0x98,0x16,0xEF,

   0xB3,0xB8,0x11,0x2A,0x6E,0x9B,0xD1,0xCC,0x37,0xC5,0xFB,0x36,0x4F,0x7F,0x00,0x00,

   0x00,0x00,0x0E,0x80,0x00,0x00,0x00,0x02,0x00,0x00,0x20,0x00,0x00,0x00,0x0C,0x92,

   0xA1,0xB9,0x50,0x34,0x45,0xE9,0xF4,0xEC,0x1D,0x8E,0xF2,0x51,0x6D,0xA1,0x95,0x1A,

   0xB9,0xE5,0x93,0x27,0xEB,0x44,0x61,0x37,0xAD,0xD4,0x73,0xB4,0x04,0xC6,0x60,0x00,

   0x00,0x00,0xA1,0x60,0x4E,0xA4,0x84,0x8A,0x7A,0x21,0x3A,0xC9,0x32,0x94,0xD0,0x0E,

   0x94,0x77,0x22,0x2B,0x05,0x42,0xB5,0xE7,0x3B,0x4B,0x2F,0x7E,0x1B,0x8A,0x77,0x79,

   0x30,0x98,0xFD,0xBB,0x06,0x22,0xAE,0x8C,0x0F,0xAA,0x9D,0xA8,0x27,0x57,0x79,0x18,

   0x8E,0x6A,0x8E,0xBD,0x4C,0x43,0xEF,0xF8,0x5B,0x7C,0xED,0x8E,0x1A,0xA0,0x63,0x8D,

   0x9E,0xBA,0xE2,0x60,0xA8,0x99,0xCE,0xFC,0xE7,0xE8,0x80,0xC0,0xFA,0x71,0x58,0x6A,

   0xC2,0x08,0x9A,0x4F,0x1B,0xFC,0x47,0x88,0x56,0x0D,0xE4,0x06,0x1A,0x53,0x66,0xFC,

   0x70,0x7C,0x40,0x00,0x00,0x00,0x40,0xEB,0xD0,0x8F,0xE7,0x12,0xF6,0x7F,0xAB,0x9A,

   0x92,0x00,0xDA,0xA1,0x1B,0xB4,0xF2,0x66,0x54,0xE7,0x92,0x10,0xFD,0xB0,0xC0,0x6B,

   0xEC,0xDF,0x20,0x11,0x63,0xB1,0xA0,0x08,0xE0,0x31,0xE5,0x4A,0x05,0xF8,0x59,0x61,

   0x91,0x2D,0x93,0xC0,0x90,0xB0,0x41,0xBF,0x14,0x53,0xEA,0x65,0x1E,0xC5,0x95,0x98,

   0xFA,0x5A,0xB8,0x70,0xFA,0x64

   };

   BYTE url[66]{

   0x68,0x00,0x74,0x00,0x74,0x00,0x70,0x00,0x3A,0x00,0x2F,0x00,0x2F,0x00,0x77,0x00,

   0x77,0x00,0x77,0x00,0x2E,0x00,0x33,0x00,0x76,0x00,0x62,0x00,0x6F,0x00,0x6F,0x00,

   0x6B,0x00,0x73,0x00,0x2E,0x00,0x63,0x00,0x6F,0x00,0x6D,0x00,0x2F,0x00,0x6C,0x00,

   0x6F,0x00,0x67,0x00,0x69,0x00,0x6E,0x00,0x2E,0x00,0x70,0x00,0x68,0x00,0x70,0x00

   };

   DataIn.pbData = (byte*)bpkey;

   DataIn.cbData = 310;

   DataOut.cbData = 0;

   DataOut.pbData = 0;

   pOptionalEntropy.pbData = (BYTE*)url;

   pOptionalEntropy.cbData = 66;

   if (CryptUnprotectData(

   &DataIn,

   0,

   &pOptionalEntropy, // Optional entropy

   NULL, // Reserved

   NULL, // Here, the optional

   // prompt structure is not

   // used.

   1,

   &DataOut))

   {

   convert((int*)DataOut.pbData, DataOut.cbData);

   //printf("%s", result);

   LocalFree(DataOut.pbData);

   }

   else

   {

   printf("%d", GetLastError());

   printf("Decryption error!");

   }

   system("pause");

   return 0;

  }

  unsigned int convert(int* a1, unsigned int a5)

  {

   int *v5; // esi@1

   unsigned int result; // eax@1

   int v7; // edi@1

   BYTE * v8; // eax@2

   size_t v9; // eax@3

   int v10; // ebx@3

   WCHAR* v13;

   size_t v11; // edi@4

   WCHAR* v12; // [sp+8h] [bp-4h]@3

   v5 = (int *)(a1 + 1);

   printf("%x\t%x\n", v5,a1);

   int v6 = *v5 + *a1;

   if (v6 + 2 < a5) {

   v8 = (BYTE*)a1 + a5;

   //printf("%x", v8);

   *(v8 - 1) = 0;

   *(v8 - 2) = 0;

   //do

   //{

   printf("%x\n", v6);

   v12 = (WCHAR*)(v6/4 + a1);

   printf("%ls\n", v12);

   v9 = wcslen(v12);

   v10 = v6 + 2 * v9 + 2;

   result = v10+2;

   if (result > a5)

   return 1;

   printf("%x\n", v10);

   v13 = (WCHAR*)(v10 + (BYTE*)a1);

   printf("%ls", v13);

   v11 = 2 * wcslen((const wchar_t *)(v10/4 + a1));

   //(**a2)(a3, a4, v12, v10 + v5);

   //} while (v6 + 2 < a5);

   }

   return 0;

  }
上面是我还原的关键算法,
运行结果:

另外吐槽一下od的udd保存的文件注释那些竟然只看文件名,不看路径,我在od里写的注释在载入其他程序的时候全都没了,心塞......
本文由看雪论坛 clay 原创,看雪ID:clay http://bbs.pediy.com/user-757651
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原文链接:[原创]一次逆向fb寻找密码的记录及还原相关算法-『软件逆向』-看雪安全论坛

  一次逆向fb寻找密码的记录及还原相关算法

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