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AA-2007.0074                  AUSCERT Advisory

                             [Win][UNIX/Linux]
             New version of OpenSSH fixes X11 cookie fallback
                              7 February 2008
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        AusCERT Advisory Summary
        ------------------------

Product:              OpenSSH 4.7
Operating System:     UNIX variants (UNIX, Linux, OSX)
                      Windows
Impact:               Reduced Security
Access:               Existing Account
CVE Names:            CVE-2007-4752
Member content until: Wednesday, October 03 2007

Revision History:     February  7 2008: Corrected Year
                      February  6 2008: Added CVE
                      September 5 2007: Initial Release


OVERVIEW:

        A new version of OpenSSH (version 4.7) has just been released. This
        version fixes a problem with X11 cookie creation.


IMPACT:

        Previous versions of OpenSSH allowed ssh to use a trusted X11
        cookie if the creation of an untrusted cookie failed.

	The X11 cookie is used to check the access rights to the X11 display.
	So a session with an untrusted cookie would not be allowed to steal
	or modify data of a trusted X11 client.


MITIGATION:

        OpenSSH version 4.7 corrects this problem and contains a number
	of additional bug fixes. OpenSSH is currently available for
	download [1].


REFERENCES:

	[1] OpenSSH
	    http://openssh.org/


AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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