RealPlayer Arbitrary File Deletion Vulnerability (#NISR19012005f)

From: NGSSoftware Insight Security Research (nisr_at_NEXTGENSS.COM)
Date: 01/19/05

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    Date:         Wed, 19 Jan 2005 17:00:08 -0000
To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM

    NGSSoftware Insight Security Research Advisory

    Name: RealPlayer Arbitrary File Deletion Vulnerability
    Systems Affected: RealPlayer 10.5 (6.0.12.1040) and older
    Severity: High
    Vendor URL: http://www.real.com/
    Author: John Heasman [ john@ngssoftware.com ]
    Date of Public Advisory: 19th January 2004
    Advisory number: #NISR19012005f
    Advisory URL: http://www.ngssoftware.com/advisories/real-02full.txt
    Reference: http://www.ngssoftware.com/advisories/real-01.txt

    Description
    ***********

    A vulnerability has been discovered in RealPlayer which can allow an
    attacker to delete arbitrary files from a users system through a specially
    crafted webpage with little user interaction.

    Details
    *******

    RealPlayer supports a proprietary package delivery file type, aptly named
    Real Metadata Packages. These files contain an HTML style language which
    contains information and resource urls for various packages and extensions
    to RealPlayer.

    One of the supported tags within the RMP file type is the <FILENAME> tag.
    This is designed to point to a relative file which is to be downloaded.
    If the file which is to be downloaded already exists on the system, it
    will delete this file without warning.

    It is also possible to insert directory traversal character sequences in
    the file name to break out of the download directory, and to point to any
    existing file on the system.

    Before the the deletion takes place, RealPlayer ensures that the file
    extension is among those listed in the formats.ini file located at:

    C:\Program Files\Real\RealPlayer\DataCache\Formats\formats.ini

    It is possible to bypass this file extension check in the follow manner
    due to a lack in the file extension validation process:

    <FILENAME>../../../../../windows/system32/notepad.exe?.mp3</FILENAME>

    Fix Information
    ***************

    RealNetworks have released an update for the Real Meta Package file
    deletion vulnerability which can be downloaded from:

    http://service.real.com/help/faq/security/040928_player/EN/

    A check for this vulnerability has been added to Typhon III, NGSSoftware's
    advanced vulnerability assessment scanner. For more information please
    visit the NGSSoftware website at http://www.ngssoftware.com/

    About NGSSoftware
    *****************

    NGSSoftware design, research and develop intelligent, advanced application
    security assessment scanners. Based in the United Kingdom, NGSSoftware
    have offices in the South of London and the East Coast of Scotland.
    NGSSoftware's sister company NGSConsulting, offers best of breed security
    consulting services, specialising in application, host and network
    security assessments.

    http://www.ngssoftware.com/

    Telephone +44 208 401 0070
    Fax +44 208 401 0076

    enquiries@ngssoftware.com 

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NTBugtraq Editor's Note:
Most viruses these days use spoofed email addresses. As such, using an Anti-Virus product which automatically notifies the perceived sender of a message it believes is infected may well cause more harm than good. Someone who did not actually send you a virus may receive the notification and scramble their support staff to find an infection which never existed in the first place. Suggest such notifications be disabled by whomever is responsible for your AV, or at least that the idea is considered.
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