VB6 Hack?

[DDStriker]

i've came across this block of code that executes machine code real time like i could type this in a text box and it would execute it

578B7C240C33C00FA2891F895704894F085F33C0C3

Which is just a simple routine to execute CPUID

now the code im using i downloaded and im not to sure on how it works so i was wondering if someone could explain it to me so i can do more with it thanks :D

Option Explicit

Private Type TPROC
hMem As Long
vtPtr As Long
End Type
Private aProc() As TPROC

Private Declare Function GlobalAlloc Lib "kernel32" (ByVal wFlags As Long, ByVal dwBytes As Long) As Long
Private Declare Function GlobalLock Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function GlobalFree Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function GlobalUnlock Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)

Function CpuID(ByVal strBuf As Long) As Long
RASM "578B7C240C33C00FA2891F895704894F085F33C0C3"
End Function

Private Sub Class_Initialize()
Dim b As Long
Dim a(1 To 12) As Byte
CpuID VarPtr(a(1))
End Sub

Private Sub RASM(s As String)
s = Replace$(s, " ", "")
Dim i As Long, aSize As Long, aB() As Byte
aSize = Len(s) \ 2

ReDim Preserve aB(1 To aSize)
For i = 1 To aSize
aB(i) = Val("&H" & Mid$(s, i * 2 - 1, 2))
Next

Static cp As Long
ReDim Preserve aProc(cp)
Dim hMem As Long, lPtr As Long
hMem = GlobalAlloc(0, aSize)
lPtr = GlobalLock(hMem)
CopyMemory ByVal lPtr, aB(1), aSize
GlobalUnlock hMem

aProc(cp).hMem = hMem
aProc(cp).vtPtr = VTable(cp)
VTable(cp) = lPtr
cp = cp + 1
End Sub

Private Sub Class_Terminate()
On Error GoTo E
Dim i As Long
For i = 0 To UBound(aProc)
VTable(i) = aProc(i).vtPtr
GlobalFree aProc(i).hMem
Next
E:
End Sub

Private Property Get VTable(ByVal Index As Long) As Long
Dim p As Long
Index = &H1C + Index * 4
CopyMemory p, ByVal ObjPtr(Me), 4
CopyMemory VTable, ByVal p + Index, 4
End Property

Private Property Let VTable(ByVal Index As Long, ByVal ProcPtr As Long)
Dim p As Long
Index = &H1C + Index * 4
CopyMemory p, ByVal ObjPtr(Me), 4
CopyMemory ByVal p + Index, ProcPtr, 4
End Property

so yeah thats pretty much it in a class module if anyone knows the exact (or even close to) details on how this work please let me know ^_^

the above code is fully operational if others wish to use it

Credit to Damian for this code he left this comment inthe class module

'

' Asmippets by Damian (Assembler Snippets)

' the way of calling procedures in machine codes from VB

'

' well, it's so hard to comment this stuff... if you're really eager to,

' you'd carefully step thru each single line of it and read tons

' of MSDN articles. if not, heh, it wasn't worth to comment it.

'

' general idea - replace VTable entries of class factory interface

' by links to pre-allocated memory blocks with our code.

' not a fastest way but works in both IDE and EXE, p-code and native.

'

' fastest way is replacing proc bodies in global modules - eliminates

' overhead of class methods calling and COM parameters passing. but

' no way to make it work in IDE except of using stuff like

' CallWindowProc - but this gets us back to call overhead and screws

' parameters passing.

'

not sure what the whole vtable entry class factory thingy is

and wonder if anyone knows how to implement the faster way which is the proc bodies (3rd paragraph) minus callwindowproc

[Bornish]

You may be interested in reading the following article:

http://www.codeproject.com/vb/interop/NativeCode.asp

[DDStriker]

awesome thank you very much

hehe this your code? very ingenious :p

[Bornish]

awesome thank you very much

hehe this your code? very ingenious :p

Damian's code is his code... my code is my code... but searching the net recently when published the article, i found this thread and thought you might want to read my detailed explaination about how these things work and what can be accomplished with.

PS: the embedding native code technique I've learned >10 yrs ago, when still using VB6 for daily work.

Best regards,

[DDStriker]

ahh ok well its fairly impressive i still don't fully understand it :p

[Bornish]

Thank you... seriously, if I can help you understand it, pls don't hesitate to ask.

I've tried my best to be consice but at the same time to bring it to the point where others can modify it for their own requirement.

In fact, any kind of feedback would be more than appreciated.

Regards,