一、概述
1 依然是dephi+脚本形式；
2 与前版相比加入了反调试；
3 与前版相比解密部分全部用虚拟机实现，不会用代码执行非虚拟机指令；
4 使用异常处理进入真正的解密函数。
二、脚本获取
1、通过跟踪函数Tfrmcrackme_FormShow，可以获取脚本，如下：
Function tion sptWBCallback(spt_wb_id,spt_wb_name,optionstr)
{
url='#sptWBCallback:id=';
url=url+spt_wb_id+';
eventName='+spt_wb_name;
if(optionstr)
url=url+';
params=optionstr';
location=url;
}
<script language="vbscript">
function alert(msg_str)
MsgBox msg_str,vbOKOnly + vbExclamation + vbApplicationModal,""
End Function
</script>
<body bgcolor=f0f0f0 topmargn=0 leftmargn=0 >、
<center>
<br><br><br>
<input value="" id="pswd" size=39>
</input>
<br><br><br>
<input type=button value="checkMyFlag" onclick="ckpswd();">
</center>
</body>
function ckpswd() {
key = "Simpower91";
a = document.all.pswd.value;
if (a.indexOf(key) == 0) {
l = a.length;
i = key.length;
sptWBCallback(a.substring(i, l));
} else {
alert("wrong!<" + a + "> is not my GUID ;-)");
return "1234";
}
}
function ok() {
alert("congratulations!");
}
CMShowingChanged
Tfrmcrackme_ApplicationEvents1Message
_Tfrmcrackme_FormCreate
about:blank#sptWBCallback:id=111;eventName=undefined2 在脚本部分要求输入sn前部分字符必须是“Simpower91”
3、然后通过sptWBCallback进入dephi回调函数执行校验。
三、回调函数定位-sncheck
在函数Tfrmcrackme_FormCreate中注册：0049945C
HIDWORD(v5) = v1; LODWORD(v5) = &sncheck; Teengine::TTeeFunction::InternalSetPeriod(*(Teengine::TTeeFunction **)(v1 + 824), v5); Idsyslogmessage::TIdSysLogMessage::SetTimeStamp(*(Idsyslogmessage::TIdSysLogMessage **)(v1 + 824), v6);
四、反调试
1、 在Tfrmcrackme_FormCreate中调用反调试相关函数477DDC
v10 = sub_477DDC((int)&cls_antiDebug_TAntiDebug, 1, 0); *(_DWORD *)(v1 + 828) = v10;
2、在Tfrmcrackme_FormCreate中貌似设置反调试函数：49978C
HIDWORD(v11) = v1; LODWORD(v11) = sub_49978C; Teengine::TTeeFunction::InternalSetPeriod(v10, v12, v13, v11); Idsyslogmessage::TIdSysLogMessage::SetTimeStamp(*(Idsyslogmessage::TIdSysLogMessage **)(v1 + 828), v14);
3、反调试函数477F64
int __usercall antiDebug5@<eax>(int a1@<eax>, int a2@<ebx>)
{
int v2; // esi
int v4; // [esp+0h] [ebp-408h]
v2 = a1;
Windows::FillMemory(&v4, 0x400u, 0);
DeleteFiber(&v4);
if ( GetLastError_0() == 0x57 )
{
a2 = 0;
unknown_libname_1058(v2);
}
else
{
LOBYTE(a2) = 1;
unknown_libname_1059(v2);
}
return a2;
}4、反调试函数478110
int __usercall antiDebug3@<eax>(int a1@<eax>, int a2@<ebx>)
{
if ( *(_BYTE *)(__readfsdword(0x30u) + 2) )
{
LOBYTE(a2) = 1;
unknown_libname_1059(a1);
}
else
{
a2 = 0;
unknown_libname_1058(a1);
}
return a2;
}5、反调试47814C
int __usercall antiDebug4@<eax>(int a1@<eax>, int a2@<ebx>)
{
if ( *(_DWORD *)(__readfsdword(0x30u) + 104) & 0x70 )
{
LOBYTE(a2) = 1;
unknown_libname_1059(a1);
}
else
{
a2 = 0;
unknown_libname_1058(a1);
}
return a2;
}6、反调试函数：477F64
int __usercall antiDebug5@<eax>(int a1@<eax>, int a2@<ebx>)
{
int v2; // esi
int v4; // [esp+0h] [ebp-408h]
v2 = a1;
Windows::FillMemory(&v4, 0x400u, 0);
DeleteFiber(&v4);
if ( GetLastError_0() == 0x57 )
{
a2 = 0;
unknown_libname_1058(v2);
}
else
{
LOBYTE(a2) = 1;
unknown_libname_1059(v2);
}
return a2;
}7、反调试函数4780B8
int antiDebug7()
{
HMODULE v0; // eax
HANDLE v1; // eax
v0 = LoadLibraryA("ntdll.dll");
dword_49DCC0 = (int (__stdcall *)(_DWORD, _DWORD, _DWORD, _DWORD))GetProcAddress_0(v0, "NtSetInformationThread");
v1 = GetCurrentThread();
return dword_49DCC0(v1, 17, 0, 0);
}8 、过掉反调试
#coding=utf-8 import struct from idaapi import * from idc import * from idautils import * dbg_write_memory(0x478070, '\xEB')#antiDebug2 refresh_debugger_memory() dbg_write_memory(0x47812E, '\x90\x90')#antiDebug3 refresh_debugger_memory() dbg_write_memory(0x47816C, '\x90\x90')#antiDebug4 refresh_debugger_memory() dbg_write_memory(0x4781F4, '\x90\x90')#antiDebug6 refresh_debugger_memory() dbg_write_memory(0x477F64, '\x33\xC0\xC3\x90')#antiDebug5 refresh_debugger_memory() dbg_write_memory(0x4780B8, '\x33\xC0\xC3\x90')#antiDebug7 refresh_debugger_memory()
五、sncheck分析
1、异常处理函数注册
CODE:004994A7 push dword ptr fs:[eax] CODE:004994AA mov fs:[eax], esp CODE:004994AD mov eax, offset sub_475ED8 CODE:004994B2 mov edx, ds:off_49C3D8 CODE:004994B8 mov [edx+4], eax CODE:004994BB mov eax, ds:off_49C3D8 CODE:004994C0 call sub_46590C
其中sub_475ED8为异常处理函数
signed int __cdecl sub_475ED8(_DWORD *a1, int a2, int a3)
{
signed int result; // eax
result = 1;
if ( !a1[1] )
{
if ( *a1 == 0xC0000096 )
{
*(_DWORD *)(a3 + 184) = realSnCheck;
result = 0;
}
else if ( *a1 == 0xC00000FD )
{
*(_DWORD *)(a3 + 196) -= 256;
}
}
return result;
}其中 475EBC（realSnCheck）为异常0C0000096h处理函数
2、获取vmp指令
CODE:00499530 call GetVmpCode CODE:00499535 mov [ebp+var_10], eax
其中 eax+4 为VMP指令地址， eax+8为指令大小
3、产生异常，进入 475EBC（realSnCheck）
六、 realSnCheck（ 475EBC ）
1、realSnCheck 调用477778 与之前类似
1）解密代码和指令
2）判断加密的指令是否是真实代码，如果是，这将相应代码进行重定位动态执行
3）如果是VMP指令，则进入虚拟机执行。
本题没有真实代码，所有指令都为虚拟机代码
2、最终会进入476B8C（codeExe）函数中
七、codeExe函数
int __stdcall codeExe(int a1, int codeData, int retAddr, int dataOfFile, _DWORD *a5, int *a6, _DWORD *a7)
{
struct globalInfo *global; // ebx
struct vmpInfo *vmpInfo; // esi
int v9; // edi
int v10; // ecx
int v11; // esi
int v12; // edx
int *v14; // [esp+1Ch] [ebp-380h]
void *v15; // [esp+20h] [ebp-37Ch]
int *v16; // [esp+24h] [ebp-378h]
void *v17; // [esp+28h] [ebp-374h]
int v18; // [esp+34h] [ebp-368h]
int *v19; // [esp+38h] [ebp-364h]
int v20; // [esp+3Ch] [ebp-360h]
char v21; // [esp+40h] [ebp-35Ch]
char v22; // [esp+140h] [ebp-25Ch]
_BYTE *v23; // [esp+374h] [ebp-28h]
char a4[6]; // [esp+37Ah] [ebp-22h]
int v25; // [esp+380h] [ebp-1Ch]
char *a2; // [esp+384h] [ebp-18h]
int v27; // [esp+388h] [ebp-14h]
int vmpDataSize; // [esp+38Ch] [ebp-10h]
char *v29; // [esp+390h] [ebp-Ch]
char *insSize; // [esp+394h] [ebp-8h]
int v31; // [esp+398h] [ebp-4h]
int vars0; // [esp+39Ch] [ebp+0h]
v19 = 0;
v18 = 0;
v27 = 0;
v16 = &vars0;
v15 = &loc_477095;
v14 = (int *)__readfsdword(0);
__writefsdword(0, (unsigned int)&v14);
global = sub_4760D0();
v31 = vars0 + 8;
global->retAddr = retAddr;
*(_DWORD *)&a4[2] = global->curVmpCode1;
a2 = *(char **)&a4[2];
vmpInfo = global->vmpInfo;
if ( !vmpInfo )
{
sub_4778E8(global);
vmpInfo = global->vmpInfo;
}
a4[1] = 0;
if ( vmpInfo->isVmpFlag == 1 )
{
a4[1] = 1;
simvm_Init(global, v31, 16);
}
while ( 1 )
{
callCodeDecrypt((int)global, dataOfFile, *(int *)&a4[2], &vmpDataSize);
while ( 1 )
{
while ( vmpInfo->isVmpFlag == 1 )
{
a4[0] = 0;
v25 = (int)callVmpHandle(vmpInfo, codeData, *(_BYTE **)&a4[2], (int)a4);
insSize = (char *)(v25 - *(_DWORD *)&a4[2]);
if ( dataOfFile == global->curVmpCodeAddr )
{
GetNextValueByLen(&codeData, (unsigned __int8)a4[0]);
global->curCodeAddr = codeData;
GetNextValueByLen(&dataOfFile, insSize);
global->curVmpCodeAddr = dataOfFile;
}
else
{
dataOfFile = global->curVmpCodeAddr;
codeData = global->curCodeAddr;
}
callCodeDecrypt((int)global, dataOfFile, *(int *)&a4[2], &vmpDataSize);
}
if ( ifCode_simvm_orign(vmpInfo, &a2) != 1 )
break;
a2 = *(char **)&a4[2];
a4[1] = 1;
simvm_Init(global, v31, 16);
}
insSize = &a2[-*(_DWORD *)&a4[2]];
a2 = *(char **)&a4[2];
if ( !a4[1] )
break;
a4[1] = 0;
vmpInfo->field_914 = 1;
}
if ( (signed int)insSize > 0 )
{
GetNextValueByLen(&dataOfFile, insSize);
callCodeDecrypt((int)global, dataOfFile, *(int *)&a4[2], &vmpDataSize);
}
vmpDataSize = off_49DCA8(*(_DWORD *)&a4[2], vmpDataSize, 0, &v20, 4, v14);
*a5 = vmpDataSize;
v9 = unknown_libname_29(32 - vmpDataSize - 6);
a2 = (char *)&global->field_1038 + v9;
qmemcpy(a2, *(const void **)&a4[2], vmpDataSize);
v14 = 0;
*((_BYTE *)&global->field_1038 + v9 + vmpDataSize) = 104;
unknown_libname_56(&v27, &v22);
if ( (unsigned __int8)sub_476200(v27, global->cmpReg1) )
{
unknown_libname_56(&v27, &v21);
if ( sub_466514(&str_FF_0[1], v27) != 1 )
{
insSize = (char *)sub_466514(&str___29[1], v27);
v14 = &v27;
sn11111(v27);
System::__linkproc__ LStrCopy(v14);
insSize = (char *)sub_466578(v27);
if ( vmpDataSize - 1 >= 0 )
{
v10 = vmpDataSize;
v29 = 0;
do
{
v14 = 0;
(v29++)[v9 + 4152 + (_DWORD)global] = -112;
--v10;
}
while ( v10 );
}
insSize += vmpDataSize;
vmpInfo->isVmpFlag1 = vmpInfo->isVmpFlag;
if ( (signed int)insSize <= 0 )
{
insSize += dataOfFile - global->field_1070;
v14 = (int *)&v29;
callCodeDecrypt((int)global, global->field_1070, *(int *)&a4[2], &v29);
}
v23 = sub_475A90(vmpInfo, *(int *)&a4[2], (unsigned int)insSize);
vmpInfo->isVmpFlag = vmpInfo->isVmpFlag1;
if ( !v23 )
global->curCodeAddr1 = global->curCodeAddr;
}
}
else if ( sub_466514(&str_CALL_0[1], v27) == 1 )
{
unknown_libname_56(&v27, &v21);
if ( sub_466514(&str_FF_0[1], v27) != 1 )
{
insSize = (char *)sub_466514(&str___29[1], v27);
v29 = insSize - 1;
v11 = (signed int)(insSize - 1) / 2;
a2 = (char *)&global->field_1038 + v9 + v11;
v14 = &v27;
sn11111(v27);
System::__linkproc__ LStrCopy(v14);
insSize = (char *)sub_466578(v27);
v29 = (char *)(&insSize[codeData] - ((char *)&global->field_1038 + v9));
qmemcpy(a2, &v29, vmpDataSize - v11);
}
insSize = (char *)vmpDataSize;
v23 = (_BYTE *)vmpDataSize;
}
else
{
insSize = (char *)vmpDataSize;
v23 = (_BYTE *)vmpDataSize;
}
*a7 = insSize;
insSize = (char *)retAddr;
a2 = (char *)&global->field_1038 + v9 + vmpDataSize + 1;
qmemcpy(a2, &insSize, 4u);
v14 = 0;
*((_BYTE *)&global->field_103C + v9 + vmpDataSize + 1) = -61;
*a6 = (int)&global->field_1038 + v9;
global->curCodeAddr = codeData + *a7;
global->curVmpCodeAddr = (int)&v23[dataOfFile];
unknown_libname_56(&v19, &v22);
v14 = v19;
unknown_libname_56(&v18, &v21);
v12 = *a6;
sub_47745C(vmpDataSize, v18, v14);
__writefsdword(0, (unsigned int)v15);
v17 = &loc_47709C;
System::__linkproc__ LStrArrayClr(&v18, 2);
return System::__linkproc__ LStrClr(&v27);
}
文章来源: https://bbs.pediy.com/thread-254697.htm
如有侵权请联系:admin#unsafe.sh
如有侵权请联系:admin#unsafe.sh