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Gentoo Linux Security Advisory                           GLSA 200405-19
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: Opera telnet URI handler file creation/truncation
            vulnerability
      Date: May 25, 2004
      Bugs: #50857
        ID: 200405-19

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Synopsis
========

A vulnerability exists in Opera's telnet URI handler that may allow a
remote attacker to overwrite arbitrary files.

Background
==========

Opera is a multi-platform web browser.

Affected packages
=================

    -------------------------------------------------------------------
     Package        /    Vulnerable    /                    Unaffected
    -------------------------------------------------------------------
  1  net-www/opera      < 7.50_beta1                     >= 7.50_beta1

Description
===========

The telnet URI handler in Opera does not check for leading '-'
characters in the host name. Consequently, a maliciously-crafted
telnet:// link may be able to pass options to the telnet program
itself. One example would be the following:

telnet://-nMyFile

If MyFile exists in the user's home directory and the user clicking on
the link has write permissions to it, the contents of the file will be
overwritten with the output of the telnet trace information. If MyFile
does not exist, the file will be created in the user's home directory.

Impact
======

This exploit has two possible impacts. First, it may create new files
in the user's home directory. Second, and far more serious, it may
overwrite existing files that the user has write permissions to. An
attacker with some knowledge of a user's home directory might be able
to destroy important files stored within.

Workaround
==========

Disable the telnet URI handler from within Opera.

Resolution
==========

All Opera users are encouraged to upgrade to the latest version of the
program:

    # emerge sync

    # emerge -pv ">=net-www/opera-7.50_beta1"
    # emerge ">=net-www/opera-7.50_beta1"

References
==========

  [ 1 ] iDEFENSE Security Advisory 05.12.04
        display?id=104&type=vulnerabilities&flashstatus=true

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

     http://security.gentoo.org/glsa/glsa-200405-19.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2004 Gentoo Technologies, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/1.0