Self-Deleting File - "Melting"

Post date: Mar 13, 2010 10:33:50 PM

It may be necessary for an un-install program to remove an application, as well as itself in order to completely remove the application from disk. This [collection of] snippet[s] will enable an executable to delete itself from disk whilst running.

{

Comspec Method

Ported: steve10120

Compiled: Delphi 2007

Website: hackhound.org

}

The Comspec method works under all 32bit versions of Windows (95,98,ME,NT,2000,XP), as long as the COMSPEC environment variable is defined. This is always defined (by default) to be the full path to the operating system's command interpreter. For Windows 95, this is "command.exe". For Windows NT, this is "cmd.exe". The function will only work if the executable has exited, so it is important to call this function and then exit immediately. It works by spawning a copy of the system's command interpreter, and asking it to perform the following command:

del exepath >> NUL

This deletes the current executable, and pipes the output to NUL (no output). The shell process is created with a hidden window as well, so the whole process is invisible. For more information, visit: http://www.catch22.net/tuts/selfdel

function ComSpecMelt():Boolean;

var

  szFile:  array[0..255] of Char;

  szCmd:   array[0..255] of Char;

begin

  Result := FALSE;

  if GetModuleFileName(0, szFile, 256) <> 0 then

  begin

    GetShortPathName(szFile, szFile, 256);

    lstrcpy(szCmd,'/c del ');

    lstrcat(szCmd, szFile);

    lstrcat(szCmd, ' >> NUL');

    if (GetEnvironmentVariable('ComSpec', szFile, 256) <> 0) and

       (ShellExecute(0, nil, szFile, szCmd, nil, SW_HIDE) > 32) then

      Result := TRUE;

  end;

end;

Self Deletion Unit coded by FoRSaKeN^

This unit uses code injection to delete itself.

unit DeleteUnit;

interface

uses Windows;

Procedure DeleteME(hProcess:Cardinal);

implementation

Procedure DeleteME(hProcess:Cardinal);

  Type

   TData   = Record

   _DeleteFileA : Pointer;

  _ExitThread  : Pointer;

  _Sleep       : Pointer;

   _szFile      : Pointer;

  end;

  procedure LoadProc(param: Pointer); stdcall;

var

  Inject : TData;

  begin

  Inject := TData(param^);

asm

      @del:

      push 1000

      call Inject._Sleep

      push Inject._szFile

      call Inject._DeleteFileA

      cmp  eax,0

      je   @del

      push 0

      call Inject._ExitThread

    end;

  end;

Var

  Written,ThreadID      : Cardinal;

  Params,Proc           : Pointer;

   pData                 : TData;

  Handle                : hWnd;

begin

if hProcess = 0 then exit;

//------------------------------------------------------------------------------

pData._DeleteFileA   := GetProcAddress(GetModuleHandle(kernel32),'DeleteFileA');

pData._ExitThread    := GetProcAddress(GetModuleHandle(kernel32),'ExitThread' );

pData._Sleep         := GetProcAddress(GetModuleHandle(kernel32),'Sleep'      );

//------------------------------------------------------------------------------

pData._szFile := VirtualAllocEx(hProcess, nil, Length(ParamStr(0)) + 1, $3000, $40);

WriteProcessMemory(hProcess, pData._szFile, PChar(Paramstr(0)), Length(Paramstr(0)) + 1, Written);

//------------------------------------------------------------------------------

Params  := VirtualAllocEx(hProcess, nil, SizeOf(TData),$3000, $40);

WriteProcessMemory(hProcess, Params, @pData, SizeOf(TData), Written);

if Written<>SizeOf(TData) then exit;

//------------------------------------------------------------------------------

Proc    := VirtualAllocEx(hProcess, nil, 500, $3000, $40);

WriteProcessMemory(hProcess, Proc, @LoadProc, 500, Written);

if Written<>500 then exit;

//------------------------------------------------------------------------------

Handle := CreateRemoteThread(hProcess,nil,0, Proc, Params, 0, ThreadID);

if Handle = 0 then exit;

//------------------------------------------------------------------------------

end;

end.

In the near future, I will add more self-deletion / "melting" snippets.