Gentoo: OpenSSH, Dropbear Insecure use of system() call
Posted by Benjamin D. Thomas   
Gentoo A flaw in OpenSSH and Dropbear allows local users to elevate their privileges via scp.
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Gentoo Linux Security Advisory                           GLSA 200602-11
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                                            http://security.gentoo.org/
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  Severity: Low
     Title: OpenSSH, Dropbear: Insecure use of system() call
      Date: February 20, 2006
      Bugs: #119232
        ID: 200602-11

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Synopsis
========

A flaw in OpenSSH and Dropbear allows local users to elevate their
privileges via scp.

Background
==========

OpenSSH is a free application suite consisting of server and clients
that replace tools like telnet, rlogin, rcp and ftp with more secure
versions offering additional functionality. Dropbear is an SSH server
and client designed with a small memory footprint that includes OpenSSH
scp code.

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

    -------------------------------------------------------------------
     Package            /   Vulnerable   /                  Unaffected
    -------------------------------------------------------------------
  1  net-misc/openssh       < 4.2_p1-r1                   >= 4.2_p1-r1
  2  net-misc/dropbear       < 0.47-r1                      >= 0.47-r1
    -------------------------------------------------------------------
     2 affected packages on all of their supported architectures.
    -------------------------------------------------------------------

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

To copy from a local filesystem to another local filesystem, scp
constructs a command line using 'cp' which is then executed via
system(). Josh Bressers discovered that special characters are not
escaped by scp, but are simply passed to the shell.

Impact
======

By tricking other users or applications to use scp on maliciously
crafted filenames, a local attacker user can execute arbitrary commands
with the rights of the user running scp.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All OpenSSH users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/openssh-4.2_p1-r1"

All Dropbear users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/dropbear-0.47-r1"

References
==========

  [ 1 ] CVE-2006-0225
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0225

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

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

  http://security.gentoo.org/glsa/glsa-200602-11.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 2006 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