[ GLSA 200412-01 ] rssh, scponly: Unrestricted command execution

[Thierry Carrez <koon () gentoo org>]

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Gentoo Linux Security Advisory                           GLSA 200412-01
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: rssh, scponly: Unrestricted command execution
      Date: December 03, 2004
      Bugs: #72815, #72816
        ID: 200412-01

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Synopsis
========

rssh and scponly do not filter command-line options that can be
exploited to execute any command, thereby allowing a remote user to
completely bypass the restricted shell.

Background
==========

rssh and scponly are two restricted shells, allowing only a few
predefined commands. They are often used as a complement to OpenSSH to
provide access to remote users without providing any remote execution
privileges.

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

    -------------------------------------------------------------------
     Package           /  Vulnerable  /                     Unaffected
    -------------------------------------------------------------------
  1  net-misc/scponly        < 4.0                              >= 4.0
  2  app-shells/rssh       <= 2.2.2                        Vulnerable!
    -------------------------------------------------------------------
     NOTE: Certain packages are still vulnerable. Users should migrate
           to another package if one is available or wait for the
           existing packages to be marked stable by their
           architecture maintainers.
    -------------------------------------------------------------------
     2 affected packages on all of their supported architectures.
    -------------------------------------------------------------------

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

Jason Wies discovered that when receiving an authorized command from an
authorized user, rssh and scponly do not filter command-line options
that can be used to execute any command on the target host.

Impact
======

Using a malicious command, it is possible for a remote authenticated
user to execute any command (or upload and execute any file) on the
target machine with user rights, effectively bypassing any restriction
of scponly or rssh.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All scponly users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/scponly-4.0"

Currently, there is no released version of rssh that contains a fix for
these issues. The author declared that he cannot provide a fixed
version at this time. Therefore, the rssh package has been hard-masked
prior to complete removal from Portage, and current users are advised
to unmerge the package.

References
==========

  [ 1 ] BugTraq Posting

http://www.securityfocus.com/archive/1/383046/2004-11-30/2004-12-06/0

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

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

  http://security.gentoo.org/glsa/glsa-200412-01.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

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