Search
Module:
Directory

   Desktop Functions:

   Smart Device Functions:


Show Recent Changes
Subscribe (RSS)
Misc. Pages
Comments
FAQ
Helpful Tools
Playground
Suggested Reading
Website TODO List
Support Forum
Download Visual Studio Add-In

Terms of Use
Privacy Policy
writeprocessmemory (kernel32)
 
.
Summary

C# Signature:

[DllImport("kernel32.dll",SetLastError = true)]
static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte [] lpBuffer, uint nSize, out UIntPtr lpNumberOfBytesWritten);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, IntPtr lpBuffer, uint nSize, UIntPtr lpNumberOfBytesWritten);

Warning
Do not use int or uint as out parameter, you will get a nice buffer overflow in x64. Using uint for nSize seems ok, because it is passed in register.

VB.Net Signature:

<DllImport("kernel32.dll", SetLastError:=True)> _
Public Shared Function WriteProcessMemory(ByVal hProcess As IntPtr, ByVal lpBaseAddress As IntPtr, ByVal lpBuffer As Byte(), ByVal nSize As System.UInt32, <Out()> ByRef lpNumberOfBytesWritten As IntPtr) As Boolean
End Function

Boo Signature:

[DllImport("kernel32.dll", SetLastError : true)]
protected static def WriteProcessMemory(hProcess as IntPtr, lpBaseAddress as IntPtr, lpBuffer as (byte), nSize as int, ref lpNumberOfBytesWritten as int) as bool:
     pass

User-Defined Types:

None.

Notes:

None.

Tips & Tricks:

Use the Signature with the IntPtr as lpBuffer for passing Structures, which got copied to the unmanaged Heap with Marshal.AllocHGlobal and Marshal.StructureToPtr.

Sample Code:

public int WriteByteArray( IntPtr BaseAddress, byte [] NewVal )
{
    // Return Value
    int ReturnVal;

    // Write Memory Byte Array
    ReturnVal = WriteProcessMemory( this.hProcess, BaseAddress, NewVal, NewVal.Length, out this.BytesWritten );

    return this.BytesWritten;
}

// Sample with IntPtr as lpBuffer for passing structs
public class SomeClass
{
    // Some Win32 Struct in CSharp
    [StructLayout(LayoutKind.Sequential)]
    private struct LVITEM
    {
        public UInt32 mask;
        public Int32 iItem;
        public Int32 iSubItem;
        public UInt32 state;
        public UInt32 stateMask;
        public IntPtr pszText;
        public Int32 cchTextMax;
        public Int32 iImage;
        public IntPtr lParam;
        public Int32 iIndent;
        public Int32 iGroupId;
        public UInt32 cColumns;
        public UIntPtr puColumns;
        public IntPtr piColFmt;
        public Int32 iGroup;
    }

    public void WriteStructureToProcessMemory(IntPtr processHandle, IntPtr BaseAddress)
    {
        UInt32 sizeOfLVITEM = (UInt32)Marshal.SizeOf(typeof(LVITEM));
       IntPtr ptrToLvItem = Marshal.AllocHGlobal((int)sizeOfLVITEM);
        Marshal.StructureToPtr(lvItem, ptrToLvItem, true);

        WriteProcessMemory(processHandle, BaseAddress, ptrToLvItem, sizeOfLVITEM, UIntPtr.Zero);
    }

}

'VB.Net
Public Shared Function Poke(ByVal proc As Process, ByVal target As Integer, ByVal data As Byte()) As Boolean
    Return WriteProcessMemory(proc.Handle, New IntPtr(target), data, data.Length, 0)
End Function

Alternative Managed API:

The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a ProcessMemoryChunk class to allocate and access memory of a different process.

Documentation

Please edit this page!

Do you have...

  • helpful tips or sample code to share for using this API in managed code?
  • corrections to the existing content?
  • variations of the signature you want to share?
  • additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).

 
Access PInvoke.net directly from VS:
Terms of Use
Edit This Page
Find References
Show Printable Version
Revisions