пятница, 22 июня 2012 г.

How to find IopRootDeviceNode

using static analysis only ?
Lets see

xp/w2k3/vista
From exported function IoPnPDeliverServicePowerNotification:

     lea     eax, [esp+38h+Object]
     push    eax             ; Object
     call    _KeWaitForSingleObject@20

     cmp     [esp+28h+var_20], ebx
     jge     short loc_64963A
     lea     eax, [esp+28h+var_18]
     push    eax
     push    [esp+2Ch+var_1C]
     mov     eax, _IopRootDeviceNode
     push    dword ptr [eax+0B8h]
     push    [ebp+arg_0]
     call    _PnpSetPowerVetoEvent@24


KeWaitForSingleObject called only one time in whole code graph of this function

w7/w8
Don`t contain function IoPnPDeliverServicePowerNotification in exports anymore. So we need to use other exported function IoTranslateBusAddress:

   mov     edi, edi
   push    ebp
   mov     ebp, esp
   and     esp, 0FFFFFFF8h
   sub     esp, 34h
   push    ebx
   push    esi
   push    edi
   call    ds:__imp__KeGetCurrentIrql@0

   test    al, al
   jbe     short loc_4D9BCC
loc_4D9BB7:

   mov     ecx, [ebp+arg_8]
   mov     eax, [ebp+arg_14]
   mov     [eax], ecx
   mov     ecx, [ebp+arg_C]
loc_4D9BC2:

   mov     [eax+4], ecx
   mov     al, 1
   jmp     loc_4D9D54
loc_4D9BCC:

   xor     edi, edi
   cmp     _IopRootDeviceNode, edi
   jz      short loc_4D9BB7


This requires to build graph on jmps after KeGetCurrentIrql call and analyse it's edges.
On w8 pattern the same but instruction to compare value of IopRootDeviceNode looks like

   cmp     _IopRootDeviceNode, 0

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