进程中dll模块的隐藏

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为了避免自己的某个dll模块被别人检测出来，有时候希望在自己加载一个dll之后，或者将dll注入到他人进程之后避免被检查出来。这就需要想办法抹掉
这个dll的模块信息，使得Toolhelp、psapi等枚举模块的API无法枚举它。

我们可以先简单看看Windows枚举进程内模块的办法吧：

首先是BOOL EnumProcessModules( HANDLE hProcess, HMODULE*
lphModule, DWORD cb, LPDWORD lpcbNeeded);

EnumProcessModules实际调用EnumProcessModulesInternal进行枚举。下面是vista下psapi的代码片断：

.text:514024B8 push ebx

.text:514024B9 push 18h

.text:514024BB lea eax, [ebp+stProcessBasicInfo]

.text:514024BE push eax

.text:514024BF push ebx ;ebx=0

.text:514024C0 push [ebp+hProcess]

.text:514024C3 call
ds:__imp__NtQueryInformationProcess@20 ;
NtQueryInformationProcess(x,x,x,x,x)

.text:514024C9 cmp eax, ebx

.text:514024CB jge short loc_514024E0


调用NtQueryInformationProcess获得ProcessBasicInformation，在
PROCESS_BASIC_INFORMATION结构中取得PEB地址。然后读取指定进程PEB中的数据

text:514024E0 loc_514024E0: ; CODE XREF:
EnumProcessModulesInternal(x,x,x,x,x)+24 j

.text:514024E0 mov eax, [ebp+stProcessBasicInfo.PebBaseAddress]

.text:514024E3 cmp eax, ebx

.text:514024E5 jnz short loc_514024EE

.text:514024E7 push 8000000Dh

.text:514024EC jmp short loc_514024CE

.text:514024EE ; ---------------------------------------------------------------------------

.text:514024EE

.text:514024EE loc_514024EE: ; CODE XREF:
EnumProcessModulesInternal(x,x,x,x,x)+3E j

.text:514024EE push ebx ; lpNumberOfBytesRead

.text:514024EF push 4 ; nSize

.text:514024F1 lea ecx, [ebp+Ldr]

.text:514024F4 push ecx ; lpBuffer

.text:514024F5 add eax, 0Ch

.text:514024F8 push eax ; lpBaseAddress

.text:514024F9 push [ebp+hProcess] ; hProcess

.text:514024FC mov edi,
ds:__imp__ReadProcessMemory@20 ; ReadProcessMemory(x,x,x,x,x)

.text:51402502 call edi ;
ReadProcessMemory(x,x,x,x,x) ; ReadProcessMemory(x,x,x,x,x)

这里读取的是PEB地址+0C处的四个字节。

通过WinDbg我们可以看看nt!_PEB的结构

0: kd> dt nt!_PEB

+0x000 InheritedAddressSpace : UChar

+0x001 ReadImageFileExecOptions : UChar

+0x002 BeingDebugged : UChar

+0x003 SpareBool : UChar

+0x004 Mutant : Ptr32 Void

+0x008 ImageBaseAddress : Ptr32 Void

+0x00c Ldr : Ptr32 _PEB_LDR_DATA

+0x010 ProcessParameters : Ptr32 _RTL_USER_PROCESS_PARAMETERS

……

+0C处是一个_PEB_LDR_DATA结构指针，里面包含了和LDR相关的一些数据，进程的模块链表就保存在Ldr中。下面是_PEB_LDR_DATA的结构：

0: kd> dt nt!_PEB_LDR_DATA

+0x000 Length : Uint4B

+0x004 Initialized : UChar

+0x008 SsHandle : Ptr32 Void

+0x00c InLoadOrderModuleList : _LIST_ENTRY

+0x014 InMemoryOrderModuleList : _LIST_ENTRY

+0x01c InInitializationOrderModuleList : _LIST_ENTRY

+0x024 EntryInProgress : Ptr32 Void

其中，InLoadOrderModuleList、InMemoryOrderModuleList、
InInitializationOrderModuleList就是进程当前已加载模块的链表，只是按照不同的方式排序。
EnumProcessModules是通过InMemoryOrderModuleList链表枚举的，而根据Win2k代码，ToolHelp32函
数是通过InLoadOrderModuleList枚举。这三个_LIST_ENTRY都是在一个
RTL_PROCESS_MODULE_INFORMATION结构中的成员。这个结构在2k代码中有引用，不过没有确切的定义，下面是ReactOS中
的定义，不过看起来我的vista PSAPI中使用的结构已经有所变化了，这里只作参考。

//

// Loader Data Table Entry

//

typedef struct _LDR_DATA_TABLE_ENTRY

{

LIST_ENTRY InLoadOrderLinks;

LIST_ENTRY InMemoryOrderModuleList;

LIST_ENTRY InInitializationOrderModuleList;

PVOID DllBase;

PVOID EntryPoint;

ULONG SizeOfImage;

UNICODE_STRING FullDllName;

UNICODE_STRING BaseDllName;

ULONG Flags;

USHORT LoadCount;

USHORT TlsIndex;

union

{

LIST_ENTRY HashLinks;

PVOID SectionPointer;

};

ULONG CheckSum;

union

{

ULONG TimeDateStamp;

PVOID LoadedImports;

};

PVOID EntryPointActivationContext;

PVOID PatchInformation;

} LDR_DATA_TABLE_ENTRY, *PLDR_DATA_TABLE_ENTRY;

到这里，隐藏模块的方法就已经明了了：通过PEB取得Ldr数据，拿到三个模块链表，并将要隐藏的模块断链即可。下面是主要代码实现：

BOOL HideMyself()

{

HMODULE hMod = GetModuleHandle( _T( "ntdll.dll"));

HMODULE hModMyself = GetModuleHandle( _T("dll.dll"));

pfnNtQueryInformationProcess p =
(pfnNtQueryInformationProcess)::GetProcAddress( hMod,
"NtQueryInformationProcess");



PROCESS_BASIC_INFORMATION stInfo = {0};

DWORD dwRetnLen = 0;

DWORD dw = p( GetCurrentProcess(), 0, &stInfo, sizeof(stInfo), &dwRetnLen);



PPEB pPeb = stInfo.PebBaseAddress;

PLIST_ENTRY ListHead, Current;

PLDR_DATA_TABLE_ENTRY pstEntry = NULL;



ListHead = &( stInfo.PebBaseAddress->Ldr->InLoadOrderModuleList);

Current = ListHead->Flink;

while ( Current != ListHead)

{

pstEntry = CONTAINING_RECORD( Current, LDR_DATA_TABLE_ENTRY, InLoadOrderLinks);

//DebugOutW( L"Module:%s, base:0x%X/r/n",
pstEntry->FullDllName.Buffer, pstEntry->EntryPoint);

if ( pstEntry->DllBase == hModMyself)

{

pstEntry->InLoadOrderLinks.Flink->Blink = pstEntry->InLoadOrderLinks.Blink;

pstEntry->InLoadOrderLinks.Blink->Flink = pstEntry->InLoadOrderLinks.Flink;

DebugOut( _T( "Hide injected dll."));

break;

}

Current = pstEntry->InLoadOrderLinks.Flink;

}



ListHead = &( stInfo.PebBaseAddress->Ldr->InMemoryOrderModuleList);

Current = ListHead->Flink;

while ( Current != ListHead)

{

pstEntry = CONTAINING_RECORD( Current, LDR_DATA_TABLE_ENTRY, InMemoryOrderModuleList);

DebugOutW( L"Module:%s, base:0x%X/r/n", pstEntry->FullDllName.Buffer, pstEntry->EntryPoint);

if ( pstEntry->DllBase == hModMyself)

{

pstEntry->InMemoryOrderModuleList.Flink->Blink =
pstEntry->InMemoryOrderModuleList.Blink;

pstEntry->InMemoryOrderModuleList.Blink->Flink =
pstEntry->InMemoryOrderModuleList.Flink;

DebugOut( _T( "Hide injected dll."));

break;

}

Current = pstEntry->InMemoryOrderModuleList.Flink;

}

DebugOutW( L"/r/n");



ListHead = &( stInfo.PebBaseAddress->Ldr->InInitializationOrderModuleList);

Current = ListHead->Flink;

while ( Current != ListHead)

{

pstEntry = CONTAINING_RECORD( Current, LDR_DATA_TABLE_ENTRY, InInitializationOrderModuleList);

DebugOutW( L"Module:%s, base:0x%X/r/n", pstEntry->FullDllName.Buffer, pstEntry->EntryPoint);

if ( pstEntry->DllBase == hModMyself)

{

pstEntry->InInitializationOrderModuleList.Flink->Blink =
pstEntry->InInitializationOrderModuleList.Blink;

pstEntry->InInitializationOrderModuleList.Blink->Flink =
pstEntry->InInitializationOrderModuleList.Flink;

DebugOut( _T( "Hide injected dll."));

break;

}

Current = pstEntry->InInitializationOrderModuleList.Flink;

}

//DebugOut( _T("Out HideMyself/r/n"));

return TRUE;

}


这样处理之后，通过常规的枚举进程方式已经枚举不到隐藏模块，ProcessExplorer也无法枚举。但是，通过枚举进程内存空间等非常规方法，仍然
是可以找到的。关于PSAPI和Toolhelp函数枚举模块的原理，可以逆向Windows代码，或者查找网上的代码看看就明白了。





author:forget

HideModuleFromPEB proc hInstDLL:DWORD

assume fs:nothing

mov esi,hInstDLL

xor eax,eax

mov eax,fs:[eax].TEB.Peb

mov eax,[eax].PEB.Ldr

lea eax,[eax].PEB_LDR_DATA.InLoadOrderModuleList

@@:

mov eax,[eax].LDR_MODULE.InLoadOrderModuleList.Flink

cmp esi,[eax].LDR_MODULE.BaseAddress

jnz @B

mov esi,[eax].LIST_ENTRY.Flink

mov ebx,[eax].LIST_ENTRY.Blink

mov [ebx].LIST_ENTRY.Flink,esi

mov esi,[eax].LIST_ENTRY.Blink

mov ebx,[eax].LIST_ENTRY.Flink

mov [ebx].LIST_ENTRY.Blink,esi

lea eax,[eax].LDR_MODULE.InMemoryOrderModuleList

mov esi,[eax].LIST_ENTRY.Flink

mov ebx,[eax].LIST_ENTRY.Blink

mov [ebx].LIST_ENTRY.Flink,esi

mov esi,[eax].LIST_ENTRY.Blink

mov ebx,[eax].LIST_ENTRY.Flink

mov [ebx].LIST_ENTRY.Blink,esi

ret

HideModuleFromPEB endp










我也来段 占内存用的，其中testdll是隐式连接。

void *PEB = NULL;

void *Ldr = NULL;

_LIST_ENTRY *Flink = NULL;

_LIST_ENTRY *p = NULL;

BYTE *BaseAddress = NULL;

BYTE *FullDllName = NULL;

__asm

{

mov eax,fs:[0x30]

mov PEB,eax

}

Ldr = *( ( void ** )( ( unsigned char * )PEB+0x0c ) );

Flink = (_LIST_ENTRY*)*( ( void ** )( ( unsigned char * )Ldr+ 0x0c ) );

p = Flink;

do

{

BaseAddress = *( ( BYTE ** )( ( unsigned char * )p+ 0x18 ) );

FullDllName = *( ( BYTE ** )( ( unsigned char * )p+ 0x28 ) );

LPSTR strFullDllName;

UnicodeToAnsi((LPCOLESTR)FullDllName,&strFullDllName);

if( strFullDllName )

{

if( strstr(strFullDllName,"testdll") )

{

*(LPDWORD)((LPBYTE)p + 0x38) = 1;

}

}

CO_SAFE_DELETE(strFullDllName);

p = p->Flink;

}

while ( Flink != p );

FreeLibrary(GetModuleHandle("testdll.dll"));

LPVOID lpdata = VirtualAlloc((LPVOID)NULL,1024*1024*6,MEM_COMMIT,PAGE_EXECUTE_READWRITE);

if( lpdata != (LPVOID)0x400000 )

{

return FALSE;

}





都发代码片段，我也来一个

while(modulo->BaseAddress != 0)

{

if( (ULONG_PTR)modulo->BaseAddress == DllHandle)

{

if(modulo->InInitializationOrderModuleList.Blink == NULL) return FALSE;

prec = (LDR_MODULE*)(ULONG_PTR)((ULONG_PTR)modulo->InInitializationOrderModuleList.Blink - 16);

next = (LDR_MODULE*)(ULONG_PTR)((ULONG_PTR)modulo->InInitializationOrderModuleList.Flink - 16);

prec->InInitializationOrderModuleList.Flink = modulo->InInitializationOrderModuleList.Flink;

next->InInitializationOrderModuleList.Blink = modulo->InInitializationOrderModuleList.Blink;

prec = (LDR_MODULE*)modulo->InLoadOrderModuleList.Blink;

next = (LDR_MODULE*)modulo->InLoadOrderModuleList.Flink;

prec->InLoadOrderModuleList.Flink = modulo->InLoadOrderModuleList.Flink;

prec->InMemoryOrderModuleList.Flink = modulo->InMemoryOrderModuleList.Flink;

next->InLoadOrderModuleList.Blink = modulo->InLoadOrderModuleList.Blink;

next->InMemoryOrderModuleList.Blink = modulo->InMemoryOrderModuleList.Blink;



return TRUE;

}

modulo = (LDR_MODULE*)modulo->InLoadOrderModuleList.Flink;

}











通过VirtualQueryEx函数列举出进程内虚拟内存的段，然后根据PE结构和内存属性来定位Image文件的映像基地址，即可确认以下三项数据， 该数据是连续的，

PVOID DllBase;

PVOID EntryPoint;

ULONG SizeOfImage;

在内存中搜索这个三个数据，即可定位LDR。





iceword 可能查出

from pediy