Gentoo: a2ps Insecure temporary files handling
Posted by Joe Shakespeare   
Gentoo The fixps and psmandup scripts in the a2ps package are vulnerable to symlink attacks, potentially allowing a local user to overwrite arbitrary files.

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Gentoo Linux Security Advisory                           GLSA 200501-02
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: a2ps: Insecure temporary files handling
      Date: January 04, 2005
      Bugs: #75784
        ID: 200501-02

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Synopsis
========

The fixps and psmandup scripts in the a2ps package are vulnerable to
symlink attacks, potentially allowing a local user to overwrite
arbitrary files.

Background
==========

a2ps is an Any to Postscript filter that can convert to Postscript from
many filetypes. fixps is a script that fixes errors in Postscript
files. psmandup produces a Postscript file for printing in manual
duplex mode.

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

    -------------------------------------------------------------------
     Package        /  Vulnerable  /                        Unaffected
    -------------------------------------------------------------------
  1  app-text/a2ps     < 4.13c-r2                          >= 4.13c-r2

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

Javier Fernandez-Sanguino Pena discovered that the a2ps package
contains two scripts that create insecure temporary files (fixps and
psmandup).

Impact
======

A local attacker could create symbolic links in the temporary files
directory, pointing to a valid file somewhere on the filesystem. When
fixps or psmandup is executed, this would result in the file being
overwritten with the rights of the user running the utility.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All a2ps users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=app-text/a2ps-4.13c-r2"

References
==========

  [ 1 ] Secunia SA13641
        http://secunia.com/advisories/13641/
  [ 2 ] CAN-2004-1170
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-1170

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

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

  http://security.gentoo.org/glsa/glsa-200501-02.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 Foundation, 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/2.0