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[原创]看雪CTF2019Q3 第二题WP
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发表于: 2019-9-25 17:00 6784
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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”
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);
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;
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
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 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 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 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);
}1、调用callCodeDecrypt（4774D8）对指令进行解密
2、调用callVmpHandle（475C08）对指令进行分析和执行，一直到所有指令执行完毕。
八、
callVmpHandle函数
char *__fastcall callVmpHandle(struct vmpInfo *vmpInfo, int codeAddr, _BYTE *vmpCode_1, int pinsLen)
{
struct vmpInfo *vmpInfo1; // esi
struct tempStruct tempStruct; // [esp+8h] [ebp-10h]
char *vmpCodeEnd; // [esp+10h] [ebp-8h]
int vmpCode; // [esp+14h] [ebp-4h]
vmpCode = (int)vmpCode_1;
vmpInfo1 = vmpInfo;
vmpCodeEnd = vmpCode_1;
if ( vmpInfo->isVmpFlag == 1 )
{
if ( ifCode_simvm_orign(vmpInfo, (char **)&vmpCode) == 2 )
{
vmpCodeEnd = (char *)vmpCode;
}
else
{
vmpCodeEnd = (char *)vmpCode;
if ( GetTempStructByVmpCmd(vmpInfo1, *(_BYTE *)vmpCode, &tempStruct) )
vmpCodeEnd = vmpHandle(vmpInfo1, vmpCode, (_BYTE *)pinsLen, (int)tempStruct.vmpInfo, tempStruct.copyFun);
else
vmpInfo1->isVmpFlag = 2;
}
}
return vmpCodeEnd;
}1、调用ifCode_simvm_orign判断指令类型
2、如果是VMP指令则
1）调用GetTempStructByVmpCmd函数初始化相关结构，并获取对应真实代码的处理函数（474F08）
char *__fastcall callVmpHandle(struct vmpInfo *vmpInfo, int codeAddr, _BYTE *vmpCode_1, int pinsLen)
{
struct vmpInfo *vmpInfo1; // esi
struct tempStruct tempStruct; // [esp+8h] [ebp-10h]
char *vmpCodeEnd; // [esp+10h] [ebp-8h]
int vmpCode; // [esp+14h] [ebp-4h]
vmpCode = (int)vmpCode_1;
vmpInfo1 = vmpInfo;
vmpCodeEnd = vmpCode_1;
if ( vmpInfo->isVmpFlag == 1 )
{
if ( ifCode_simvm_orign(vmpInfo, (char **)&vmpCode) == 2 )
{
vmpCodeEnd = (char *)vmpCode;
}
else
{
vmpCodeEnd = (char *)vmpCode;
if ( GetTempStructByVmpCmd(vmpInfo1, *(_BYTE *)vmpCode, &tempStruct) )
vmpCodeEnd = vmpHandle(vmpInfo1, vmpCode, (_BYTE *)pinsLen, (int)tempStruct.vmpInfo, tempStruct.copyFun);
else
vmpInfo1->isVmpFlag = 2;
}
}
return vmpCodeEnd;
}2）调用vmpHandle（474EAC）
九、
vmpHandle (474EAC)函数
char *__fastcall vmpHandle(struct vmpInfo *vmpInfo, int vmpCode, _BYTE *pinsLen1, int vmpInfo1, int vmpExeFun)
{
_BYTE *pinsLen; // esi
struct vmpInfo *vmpInfo_1; // ebx
char *vmpInsEnd; // edi
int out_size; // [esp+Ch] [ebp-14h]
char out21; // [esp+10h] [ebp-10h]
char out11; // [esp+14h] [ebp-Ch]
int out_orgReg; // [esp+18h] [ebp-8h]
int out_aimReg; // [esp+1Ch] [ebp-4h]
pinsLen = pinsLen1;
vmpInfo_1 = vmpInfo;
vmpInsEnd = copyVMPcode(vmpInfo, (char *)vmpCode);
*pinsLen = vmpInfo_1->vmpCode.codeInsLen;
getVmpReg(vmpInfo_1, &out_aimReg, &out_orgReg, &out11, &out21, &out_size);
vmpRealFunHandle((int)vmpInfo_1, out_aimReg, out_orgReg, vmpInfo1, (int (__fastcall *)(int, int))vmpExeFun, out_size);
return vmpInsEnd;
}1、调用copyVMPcode拷贝当前条VMP指令，一条指令长度为0x64
2、调用getVmpReg，应该是获取相关寄存器或者执行简单指令执行
3、执行该指令的真实指令处理函数
4、稍微分析了下虚拟指令
firt ins
+0 01 00 00 00
+4 00 00 00 00 setout1Flag
+8 17 11 01 F0 vmpcmd 1 reg1
+c 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 unknowcmd1
+2A 01
+2B 00
+2C 0C 00 00 F0 vmdcmp2
+30 00 00 00 00
+34 00 00 00 00
+38 30 00 00 00 offset
+3C 01 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04
+4E 00
+4F 02
+50 07 insSize
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
if ( vmpInfo->vmpCode.vmpCmd1 ) F0011117
{
out1 = result0Reg
out3 = [result0Reg]+offset
if(unknowcmd1 !=3)
out5 = unknowcmd1
if(setout1Flag || offset)
out1 = out3
}
//0x01
varc = fs:[offset2]
var7 = fs:[offset2] + offset1
================================================
+0 01 00 00 00
+4 00 aimreg_SetFlag
+5 00
+6 00
+7 00
+8 17 01 00 F0 aimreg_cmd
+C 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1C 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 01 aimreg_size
+2A 01
+2B 00
+2C 17 11 01 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 02 00 00 00 orgreg_offset
+3C 01 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 03
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//==============================================================
+0 01 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 02 00 00 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 EF FF FF FF aimreg_offset
+18 02 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 17 01 00 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 01 orgreg_size
+4E 00
+4F 02
+50 03
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//=====================================================
cmp [aimreg+offset], orgreg_value set global.cmpReg 0x80位
+0 08 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 02 00 00 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 EF FF FF FF aimreg_offset
+18 02 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 01 00 00 00 orgreg_value
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 04
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//==========================================================================
+0 1F 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00
+c 00 00 00 00
+10 6A 01 00 00 branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 00 orgreg_size
+4E 00
+4F 01
+50 06
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//===================================================
cmp [aimreg+offset], orgreg_value set global.cmpReg 0x80位
+0 08 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 14 11 01 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 44 03 00 00 aimreg_offset
+18 01 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 01 00 00 00 orgreg_value
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 07
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
============================================================================
+0 1F 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00 aimreg_cmd
+c 00 00 00 00
+10 5D 01 00 00 branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 00 orgreg_size
+4E 00
+4F 01
+50 06
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//====================================================
//获取输入sn的地址
mov aimreg+aimReg, [org+orgOfset]
+0 01 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 17 11 01 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 01
+2B 00
+2c 02 00 00 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 E4 FF FF FF orgreg_offset
+3C 02 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+48 00 04 00 02
+4C 03
+4D 00 orgreg_size
+4E 00
+4F 00
+50 00
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
//===================================================
+0 0B 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00 aimreg_cmd
+c 00 00 00 00
+10 6D B1 F6 FF branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+48 00 00 00 01
+4C 05 code_offset
+4D 00 orgreg_size
+4E 00
+4F 00
+50 00
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 08 00 00 00 其中如下函数vmp_opcode_0x08为处理比较指令的，跟踪到这里后即基本可以还原了。
truct vmpInfo *__userpurge vmp_opcode_0x08@<eax>(struct vmpInfo *vmpInfo@<eax>, _DWORD *out1@<edx>, _DWORD *vmpcodeLocation@<ecx>, unsigned int vmpcodeEnd@<edi>, int out5)
{
unsigned int v5; // et0
unsigned int v6; // et0
unsigned int v7; // et0
unsigned int v8; // et0
struct vmpInfo *result; // eax
switch ( out5 )
{
case 1:
v5 = __readeflags();
__writeeflags(v5);
result = vmp_opcode_0x08_setCmpFlag(
vmpInfo,
*(unsigned __int8 *)out1 - *(unsigned __int8 *)vmpcodeLocation,
1,
v5);
break;
case 2:
v6 = __readeflags();
__writeeflags(v6);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, vmpcodeEnd, 2, v6);
break;
case 4:
v7 = __readeflags();
__writeeflags(v7);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, *out1 - *vmpcodeLocation, out5, v7);
break;
default:
v8 = __readeflags();
__writeeflags(v8);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, *out1 - *vmpcodeLocation, 4, v8);
break;
}
return result;
}使用输入的字符-0x7F,然后与如下地址中的E0 B2 B1比较相等即为正确。
CODE:00499570 clts CODE:00499572 mov al, 0B1h CODE:00499574 mov dl, 0B8h CODE:00499576 mov bh, 0E0h CODE:00499578 mov dl, 0B1h CODE:0049957A mov al, 0E2h
其中 499572地址敲好在产生异常clts指令的下方。
最后得到flag为：
Simpower91a321
ps :
作者的dephi相关题目已经出到了3.0阶段
1.0 ---------------------dephi+jscrypt 内存中暴露了key
2.0---------------------- dephi+代码重定位 +VMP;虽然有vmp但是主要算法在代码重定位部分
3.0----------------------
dephi+代码重定位 +VMP：所有代码都在vmp
4.0----------------------
dephi+代码重定位 +VMP:算法复杂化？？？？？？？？？？？？
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);
}1、调用callCodeDecrypt（4774D8）对指令进行解密
2、调用callVmpHandle（475C08）对指令进行分析和执行，一直到所有指令执行完毕。
八、
callVmpHandle函数
char *__fastcall callVmpHandle(struct vmpInfo *vmpInfo, int codeAddr, _BYTE *vmpCode_1, int pinsLen)
{
struct vmpInfo *vmpInfo1; // esi
struct tempStruct tempStruct; // [esp+8h] [ebp-10h]
char *vmpCodeEnd; // [esp+10h] [ebp-8h]
int vmpCode; // [esp+14h] [ebp-4h]
vmpCode = (int)vmpCode_1;
vmpInfo1 = vmpInfo;
vmpCodeEnd = vmpCode_1;
if ( vmpInfo->isVmpFlag == 1 )
{
if ( ifCode_simvm_orign(vmpInfo, (char **)&vmpCode) == 2 )
{
vmpCodeEnd = (char *)vmpCode;
}
else
{
vmpCodeEnd = (char *)vmpCode;
if ( GetTempStructByVmpCmd(vmpInfo1, *(_BYTE *)vmpCode, &tempStruct) )
vmpCodeEnd = vmpHandle(vmpInfo1, vmpCode, (_BYTE *)pinsLen, (int)tempStruct.vmpInfo, tempStruct.copyFun);
else
vmpInfo1->isVmpFlag = 2;
}
}
return vmpCodeEnd;
}1、调用ifCode_simvm_orign判断指令类型
2、如果是VMP指令则
1）调用GetTempStructByVmpCmd函数初始化相关结构，并获取对应真实代码的处理函数（474F08）
char *__fastcall callVmpHandle(struct vmpInfo *vmpInfo, int codeAddr, _BYTE *vmpCode_1, int pinsLen)
{
struct vmpInfo *vmpInfo1; // esi
struct tempStruct tempStruct; // [esp+8h] [ebp-10h]
char *vmpCodeEnd; // [esp+10h] [ebp-8h]
int vmpCode; // [esp+14h] [ebp-4h]
vmpCode = (int)vmpCode_1;
vmpInfo1 = vmpInfo;
vmpCodeEnd = vmpCode_1;
if ( vmpInfo->isVmpFlag == 1 )
{
if ( ifCode_simvm_orign(vmpInfo, (char **)&vmpCode) == 2 )
{
vmpCodeEnd = (char *)vmpCode;
}
else
{
vmpCodeEnd = (char *)vmpCode;
if ( GetTempStructByVmpCmd(vmpInfo1, *(_BYTE *)vmpCode, &tempStruct) )
vmpCodeEnd = vmpHandle(vmpInfo1, vmpCode, (_BYTE *)pinsLen, (int)tempStruct.vmpInfo, tempStruct.copyFun);
else
vmpInfo1->isVmpFlag = 2;
}
}
return vmpCodeEnd;
}2）调用vmpHandle（474EAC）
九、
vmpHandle (474EAC)函数
char *__fastcall vmpHandle(struct vmpInfo *vmpInfo, int vmpCode, _BYTE *pinsLen1, int vmpInfo1, int vmpExeFun)
{
_BYTE *pinsLen; // esi
struct vmpInfo *vmpInfo_1; // ebx
char *vmpInsEnd; // edi
int out_size; // [esp+Ch] [ebp-14h]
char out21; // [esp+10h] [ebp-10h]
char out11; // [esp+14h] [ebp-Ch]
int out_orgReg; // [esp+18h] [ebp-8h]
int out_aimReg; // [esp+1Ch] [ebp-4h]
pinsLen = pinsLen1;
vmpInfo_1 = vmpInfo;
vmpInsEnd = copyVMPcode(vmpInfo, (char *)vmpCode);
*pinsLen = vmpInfo_1->vmpCode.codeInsLen;
getVmpReg(vmpInfo_1, &out_aimReg, &out_orgReg, &out11, &out21, &out_size);
vmpRealFunHandle((int)vmpInfo_1, out_aimReg, out_orgReg, vmpInfo1, (int (__fastcall *)(int, int))vmpExeFun, out_size);
return vmpInsEnd;
}1、调用copyVMPcode拷贝当前条VMP指令，一条指令长度为0x64
2、调用getVmpReg，应该是获取相关寄存器或者执行简单指令执行
3、执行该指令的真实指令处理函数
4、稍微分析了下虚拟指令
firt ins
+0 01 00 00 00
+4 00 00 00 00 setout1Flag
+8 17 11 01 F0 vmpcmd 1 reg1
+c 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 unknowcmd1
+2A 01
+2B 00
+2C 0C 00 00 F0 vmdcmp2
+30 00 00 00 00
+34 00 00 00 00
+38 30 00 00 00 offset
+3C 01 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04
+4E 00
+4F 02
+50 07 insSize
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
if ( vmpInfo->vmpCode.vmpCmd1 ) F0011117
{
out1 = result0Reg
out3 = [result0Reg]+offset
if(unknowcmd1 !=3)
out5 = unknowcmd1
if(setout1Flag || offset)
out1 = out3
}
//0x01
varc = fs:[offset2]
var7 = fs:[offset2] + offset1
================================================
+0 01 00 00 00
+4 00 aimreg_SetFlag
+5 00
+6 00
+7 00
+8 17 01 00 F0 aimreg_cmd
+C 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1C 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 01 aimreg_size
+2A 01
+2B 00
+2C 17 11 01 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 02 00 00 00 orgreg_offset
+3C 01 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 03
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//==============================================================
+0 01 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 02 00 00 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 EF FF FF FF aimreg_offset
+18 02 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 17 01 00 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 01 orgreg_size
+4E 00
+4F 02
+50 03
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//=====================================================
cmp [aimreg+offset], orgreg_value set global.cmpReg 0x80位
+0 08 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 02 00 00 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 EF FF FF FF aimreg_offset
+18 02 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 01 00 00 00 orgreg_value
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 04
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//==========================================================================
+0 1F 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00
+c 00 00 00 00
+10 6A 01 00 00 branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 00 00 00 00 orgreg_offset
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 00 orgreg_size
+4E 00
+4F 01
+50 06
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//===================================================
cmp [aimreg+offset], orgreg_value set global.cmpReg 0x80位
+0 08 00 00 00
+4 01 00 00 00 aimreg_SetFlag
+8 14 11 01 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 44 03 00 00 aimreg_offset
+18 01 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 01 00 00 00 orgreg_value
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 04 orgreg_size
+4E 01
+4F 02
+50 07
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
============================================================================
+0 1F 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00 aimreg_cmd
+c 00 00 00 00
+10 5D 01 00 00 branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+4C 00
+4D 00 orgreg_size
+4E 00
+4F 01
+50 06
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 00 00 00 00
//====================================================
//获取输入sn的地址
mov aimreg+aimReg, [org+orgOfset]
+0 01 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 17 11 01 F0 aimreg_cmd
+c 00 00 00 00
+10 00 00 00 00
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 01
+2B 00
+2c 02 00 00 F0 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00 orgreg_value
+38 E4 FF FF FF orgreg_offset
+3C 02 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+48 00 04 00 02
+4C 03
+4D 00 orgreg_size
+4E 00
+4F 00
+50 00
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
//===================================================
+0 0B 00 00 00
+4 00 00 00 00 aimreg_SetFlag
+8 00 00 00 00 aimreg_cmd
+c 00 00 00 00
+10 6D B1 F6 FF branch_offset
+14 00 00 00 00 aimreg_offset
+18 00 00 00 00
+1c 00 00 00 00
+20 00 00 00 00
+24 00 00 00 00
+28 00
+29 04 aimreg_size
+2A 00
+2B 00
+2c 00 00 00 00 orgreg_cmd
+30 00 00 00 00
+34 00 00 00 00
+38 00 00 00 00
+3C 00 00 00 00
+40 00 00 00 00
+44 00 00 00 00
+48 00 00 00 00
+48 00 00 00 01
+4C 05 code_offset
+4D 00 orgreg_size
+4E 00
+4F 00
+50 00
+51 00
+52 00
+53 00
+54 00 00 00 00
+58 00 00 00 00
+5C 00 00 00 00
+60 08 00 00 00 其中如下函数vmp_opcode_0x08为处理比较指令的，跟踪到这里后即基本可以还原了。
truct vmpInfo *__userpurge vmp_opcode_0x08@<eax>(struct vmpInfo *vmpInfo@<eax>, _DWORD *out1@<edx>, _DWORD *vmpcodeLocation@<ecx>, unsigned int vmpcodeEnd@<edi>, int out5)
{
unsigned int v5; // et0
unsigned int v6; // et0
unsigned int v7; // et0
unsigned int v8; // et0
struct vmpInfo *result; // eax
switch ( out5 )
{
case 1:
v5 = __readeflags();
__writeeflags(v5);
result = vmp_opcode_0x08_setCmpFlag(
vmpInfo,
*(unsigned __int8 *)out1 - *(unsigned __int8 *)vmpcodeLocation,
1,
v5);
break;
case 2:
v6 = __readeflags();
__writeeflags(v6);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, vmpcodeEnd, 2, v6);
break;
case 4:
v7 = __readeflags();
__writeeflags(v7);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, *out1 - *vmpcodeLocation, out5, v7);
break;
default:
v8 = __readeflags();
__writeeflags(v8);
result = vmp_opcode_0x08_setCmpFlag(vmpInfo, *out1 - *vmpcodeLocation, 4, v8);
break;
}
return result;
}使用输入的字符-0x7F,然后与如下地址中的E0 B2 B1比较相等即为正确。
CODE:00499570 clts CODE:00499572 mov al, 0B1h CODE:00499574 mov dl, 0B8h CODE:00499576 mov bh, 0E0h CODE:00499578 mov dl, 0B1h CODE:0049957A mov al, 0E2h
其中 499572地址敲好在产生异常clts指令的下方。
最后得到flag为：
Simpower91a321
ps :
作者的dephi相关题目已经出到了3.0阶段
1.0 ---------------------dephi+jscrypt 内存中暴露了key
2.0---------------------- dephi+代码重定位 +VMP;虽然有vmp但是主要算法在代码重定位部分
3.0----------------------
dephi+代码重定位 +VMP：所有代码都在vmp
4.0----------------------
dephi+代码重定位 +VMP:算法复杂化？？？？？？？？？？？？
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
#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
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
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
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
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最后于 2019-9-25 17:53
被oooAooo编辑
，原因：
赞赏
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哦哦,原来是这样子,'嗯'我已经完全搞懂了
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这题最牛的是，如果调试的时候输入了正确的结果，也提示错误！！！让我完美的错过了侥幸获取flag的机会。
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师傅，你这个脚本编写的时候那几个地址的来历可以普及下吗
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