I. BACKGROUND
MPlayer is a movie player for Linux that also runs on many other Unices,
and non- x86 CPUs. It plays most MPEG, VOB, AVI, Ogg/OGM, VIVO,
ASF/WMA/WMV, QT/MOV/MP4, FLI, RM, NuppelVideo, YUV4MPEG, FILM, RoQ, PVA
files, supported by many native, XAnim, and Win32 DLL codecs. You can
watch VideoCD, SVCD, DVD, 3ivx, DivX 3/4/5 and other formats.
More information is available at http://mplayerhq.hu/.
II. DESCRIPTION
Remote exploitation of a stack overflow vulnerability in MPlayer could
allow remote users to gain access to the computer.
The vulnerability specifically exists due to a lack of bounds checking
in /libmpdemux/asf_mmst_straming.c. If a specially crafted file
specifies a large value for the length field, the overflow is triggered
in get_data(). The vulnerable code follows:
static int get_media_packet (int s, int padding, streaming_ctrl_t *stream_ctrl) {
unsigned char pre_header[8];
char data[BUF_SIZE];
[...]
packet_len = get_32 ((unsigned char*)&packet_len, 0) + 4;
[!] if (!get_data (s, data, packet_len)) {
printf ("command data read failed\n");
return 0;
}
[...]
Once the get_data function overwrites stack memory, the saved return
address can be controlled, thus allowing for execution of arbitrary
code.
III. ANALYSIS
If remote exploitation is successful, the attacker would be able to gain
access with the privileges of the user who attempted to view the stream.
IV. DETECTION
iDEFENSE has confirmed that MPlayer version 1.0pre5 is vulnerable.
The following distributions of Linux include MPlayer:
Gentoo Linux
SUSE Linux
V. WORKAROUND
Users must be careful when accepting and opening media from untrusted
sources. Do not accept media from those you do not trust. Do not stream
media from servers you do not trust.
VI. VENDOR RESPONSE
A patch to address this vulnerability is available at:
http://www1.mplayerhq.hu/MPlayer/patches/mmst_fix_20041215.diff
VII. CVE INFORMATION
A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.
VIII. DISCLOSURE TIMELINE
12/10/2004 Initial vendor notification
12/16/2004 Public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp
X. LEGAL NOTICES
Copyright © 2004 iDEFENSE, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.
Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.
