Linksys router vulnerability

From: Seth Bromberger (sbbugtraq1102@yahoo.com)
Date: 11/18/02

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    Date: Mon, 18 Nov 2002 14:00:14 -0800 (PST)
    From: Seth Bromberger <sbbugtraq1102@yahoo.com>
    To: bugtraq@securityfocus.com
    
    

    SUMMARY:
    Linksys products running affected firmware versions
    are susceptible to a bug that allows unauthenticated
    access to the management interface. This bug affects
    both local and remote management (if enabled).

    AFFECTED PRODUCTS (per Linksys support):
    BEFSR41, BEFSR11, BEFSRU31:
      firmware versions from 1.41 through 1.43
    BEFW11S4:
      firmware versions from 1.42.7 through 1.43.

    IMPACT:
    Users on the protected ("local") network can gain
    administrative access to the Linksys router and may
    view/alter configuration data. If remote management
    is enabled, users on the unprotected ("wide-area")
    network may gain similar access.

    Note that for the BEFW11S4, the "local" network
    includes all devices able to associate with the access
    point.

    RESOLUTION:
    Linksys has released firmware version 1.43.3 that
    resolves this issue on the tested equipment (BEFSR41).
     It is assumed that the problem is resolved with this
    firmware version on all affected products.

    DETAIL:
    It appears that the Linksys HTTP management interface
    does not handle cases where the client sends specific
    XML-related data during the initial content
    negotiation ("XML related entries in the mailcap
    file").

    VERIFICATION/TEST SETUP:
    Test setup included the following hardware/software:
    - BEFSR41 firewall/router with firmware version 1.43
    - lynx browser version 2.8.4rel.1 (17 Jul 2001)
    - ~/.mailcap with the following line:
    application/foo.xml;

    Using lynx with the above mailcap, connect to the
    management interface (remote interface listens on port
    8080 when enabled). Affected versions will display
    the setup screen without requiring the user to enter a
    password. (Note: mailcap is generally installed as
    ~/.mailcap). Navigation to other screens is possible,
    though some "accept" buttons might not render if the
    browser used is unable to process javascript.

    TIMELINE:
    Linksys was notified of this bug on 11 November 2002.
    The bug was confirmed on 12 November 2002. A beta
    firmware update was tested on 15 November 2002; the
    new firmware (1.43.3, 11/15/2002) is now available on
    the Linksys web site.

    THANKS:
    Andreas Bang and Jay Price at Linksys were
    instrumental in determining the scope of this problem,
    and provided prompt, detailed feedback.

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