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RealNetworks RealPlayer/HelixPlayer RealPix Format String Vulnerability

09.30.05

BACKGROUND

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

DESCRIPTION

Remote exploitation of a format string vulnerability in RealPix (.rp)
file format parser within various versions of RealNetworks Inc.'s
RealPlayer could allow attackers to execute arbitrary code.

The vulnerability specifically exists because of the improper usage of a
formatted printing function. When a user specifies an invalid value for
the "timeformat" attribute describing a RealPix file, the data is passed
to the function.

The following stripped down .rp file is sufficient enough to trigger the
vulnerability:

   <imfl>
   <head
   title="iDEFENSE Labs RealPix Vulnerability"
   timeformat="%n%n%n%n%n%n"/>
   </imfl>

ANALYSIS

Exploitation allows for arbitrary code execution as the user who opened
the .rp file.

Exploitation requires an attacker to craft a malicious .rp file and
convince a user to open it. An attacker could also trick a user to load
the .rp file from a normal web page under the attacker's control; this
is possible if the user has configured their web browser to handle
RealPlayer formats automatically.

DETECTION

iDEFENSE Labs has confirmed that RealPlayer 10.0.4.750 on Linux is
vulnerable. Windows and Mac versions of RealPlayer are not vulnerable.
FreeBSD versions are suspected vulnerable.

The vendor has indicated that the following versions are vulnerable:
   Linux RealPlayer 10 (10.0.0 - 10.0.5)
   Helix Player (10.0.0 - 10.0.5)

The following vendors include susceptible RealPlayer packages within
their respective distributions:

  The FreeBSD Project: FreeBSD 5.3 and earlier
  Novell Inc.: SuSE Linux 9.2 
  Red Hat Inc.: Red Hat Enterprise Linux Extras v.3 and v.4
    Red Hat Enterprise Linux v.4
    Fedora Core 3 and 4

WORKAROUND

Filter .rp attachments at e-mail gateways. Educate users about the risks
of accepting files from untrusted individuals.

VENDOR RESPONSE

The vendor had released the following advisory for this vulnerability:

   http://service.real.com/help/faq/security/050930_player/EN/

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2710 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

DISCLOSURE TIMELINE

08/23/2005   Initial vendor notification
09/02/2005   Initial vendor response
09/30/2005   Coordinated public disclosure

CREDIT

iDEFENSE Labs is credited with this discovery.

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LEGAL NOTICES

Copyright © 2005 Verisign, 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,
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