From: idlabs-advisories at idefense.com (idlabs-advisories@...fense.com)
Subject: iDEFENSE Security Advisory 06.10.04: Real Networks RealPlayer URL
 Parsing Buffer Overflow Vulnerability

Real Networks RealPlayer URL Parsing Buffer Overflow Vulnerability

iDEFENSE Security Advisory 06.10.04
www.idefense.com/application/poi/display?id=109&type=vulnerabilities
June 10, 2004 

I. BACKGROUND

RealPlayer is an application for playing various media formats,
developed by RealNetworks Inc. For more information, visit
http://www.real.com/

II. DESCRIPTION

Remote exploitation of a buffer overflow in Version 10 of Real Networks'
RealPlayer could allow execution of arbitrary commands.

The vulnerability specifically exists in the handling of URLs with a
large number of period (".") characters. By creating a specially crafted
filename, it is possible to cause the execution of arbitrary code with
the permissions of the user that attempts to access it.

III. ANALYSIS

One method of exploiting this vulnerability is to place a .RAM file
(RealPlayer Presentation) containing a maliciously constructed URL on a
web server and send an e-mail to the target with a link containing the
file.

It appears the vulnerability results from allocating an array of a fixed
size and then iterating through the URL looking for periods. As each one
is found, a pointer to it is stored in the array, and the current index
is incremented. No check seems to be done for writes to addresses
outside the array.

IV. DETECTION

RealNetworks' RealPlayer 10 is confirmed vulnerable. Previous versions
of RealPlayer are also suspected to be vulnerable.

V. WORKAROUND

iDEFENSE is currently unaware of any effective workarounds for this
vulnerability.

User awareness is the best defense against this class of attack. Users
should be aware of the existence of such attacks and proceed with
caution when following links from suspicious and/or unsolicited e-mail.

VI. VENDOR RESPONSE

Real Networks recommends updating affected applications to the latest
version. Instructions for upgrading are contained in the vendor's
security advisory located at:

http://service.real.com/help/faq/security/040610_player/EN/

VII. CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.

VIII. DISCLOSURE TIMELINE

04/14/2004       Exploit discovered by iDEFENSE
05/12/2004       Initial vendor notification
05/12/2004       iDEFENSE clients notified
05/13/2004       Vendor response
06/10/2004       Coordinated public disclosure

IX. CREDIT

Greg MacManus (iDEFENSE Labs) is credited with this discovery.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

X. LEGAL NOTICES

Copyright (c) 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@...fense.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.

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