Gentoo: PuTTY Remote code execution
Posted by Benjamin D. Thomas   
Gentoo PuTTY was found to contain vulnerabilities that can allow a malicious SFTP server to execute arbitrary code on unsuspecting PSCP and PSFTP clients.
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Gentoo Linux Security Advisory                           GLSA 200502-28
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: PuTTY: Remote code execution
      Date: February 21, 2005
      Bugs: #82753
        ID: 200502-28

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Synopsis
========

PuTTY was found to contain vulnerabilities that can allow a malicious
SFTP server to execute arbitrary code on unsuspecting PSCP and PSFTP
clients.

Background
==========

PuTTY is a popular SSH client, PSCP is a secure copy implementation,
and PSFTP is a SSH File Transfer Protocol client.

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

    -------------------------------------------------------------------
     Package         /  Vulnerable  /                       Unaffected
    -------------------------------------------------------------------
  1  net-misc/putty       < 0.57                               >= 0.57

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

Two vulnerabilities have been discovered in the PSCP and PSFTP clients,
which can be triggered by the SFTP server itself. These issues are
caused by the improper handling of the FXP_READDIR response, along with
other string fields.

Impact
======

An attacker can setup a malicious SFTP server that would send these
malformed responses to a client, potentially allowing the execution of
arbitrary code on their system.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All PuTTY users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/putty-0.57"

References
==========

  [ 1 ] PuTTY vulnerability vuln-sftp-readdir
        http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-sftp-readdir.html
  [ 2 ] PuTTY vulnerability vuln-sftp-string
        http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-sftp-string.html
  [ 3 ] CAN-2005-0467
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0467
  [ 4 ] iDEFENSE Advisory
        http://www.idefense.com/application/poi/display?id=201&type=vulnerabilities

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

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

  http://security.gentoo.org/glsa/glsa-200502-28.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 2005 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