Apple Darwin Streaming Server DESCRIBE Null Byte Denial of Service
Vulnerability

iDEFENSE Security Advisory 12.03.2004
www.idefense.com/application/poi/display?id=159&type=vulnerabilities
December 03, 2004

I. BACKGROUND

Darwin Streaming Server is an open source version of Apple's QuickTime
Streaming Server technology that allows you to send streaming media to
clients across the Internet using the industry standard RTP and RTSP
protocols.

II. DESCRIPTION

Remote exploitation of an input validation vulnerability in Apple
Computer Inc.'s Darwin Streaming Server allows attackers to cause a
denial of service condition. The vulnerability specifically occurs due
to insufficient sanity checking on arguments to DESCRIBE requests. A
remote attacker can send a request for a location containing a null byte
to cause a denial of service condition resulting in the following
backtrace:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1026 (LWP 9648)]
0x4207ac9e in chunk_free () from /lib/i686/libc.so.6
(gdb) bt
#0 0x4207ac9e in chunk_free () from /lib/i686/libc.so.6
#1 0x4207ac24 in free () from /lib/i686/libc.so.6
#2 0x08096406 in FindOrCreateSession (inPath=0x408caf3c,
   inParams=0x81746f0, inData=0x0, isPush=0, foundSessionPtr=0x0) at
   APIModules/QTSSReflectorModule/QTSSReflectorModule.cpp:1262

III. ANALYSIS

Successful exploitation allows any remote unauthenticated attacker to
crash the targeted server, thereby preventing legitimate users from
accessing streamed content.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in Darwin
Streaming Server 5.0.1. It is suspected that earlier versions are also
vulnerable.

V. WORKAROUND

Employ firewalls, access control lists or other TCP/UDP restriction
mechanisms to limit access to systems and services.

VI. VENDOR RESPONSE

The following updates are available from Apple Downloads
(http://www.apple.com/support/downloads//) to address this
vulnerability:

Mac OS X 10.2.8 Client
http://www.apple.com/support/downloads//securityupdate_2004-12-02_v_1_0_
(Mac_OS_X_10_2_8_Client).html

Mac OS X 10.2.8 Server
http://www.apple.com/support/downloads//securityupdate_2004-12-02_v_1_0_
(Mac_OS_X_10_2_8_Server).html

Mac OS X 10.3.6 Client
http://www.apple.com/support/downloads//securityupdate_2004-12-02_v_1_0_
(Mac_OS_X_10_3_6_Client).html

Mac OS X 10.3.6 Server
http://www.apple.com/support/downloads//securityupdate_2004-12-02_v_1_0_
(Mac_OS_X_10_3_6_Server).html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2004-1123 to these issues. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

09/10/2004   Initial vendor notification
09/15/2004   Initial vendor response
12/03/2004   Coordinated 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 (c) 2004 iDEFENSE, Inc.

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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.