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ASB-2011.0107 - ALERT [Netware] XNFS Server: Execute arbitrary code/commands - Remote/unauthenticated

Date: 25 November 2011
References: ESB-2011.0217  

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===========================================================================
                         AUSCERT Security Bulletin

                               ASB-2011.0107
                       NetWare XNFS security update
                             25 November 2011

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              XNFS Server
Operating System:     Netware
Impact/Access:        Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Resolution:           Patch/Upgrade
CVE Names:            CVE-2011-4191  
Member content until: Sunday, December 25 2011
Reference:            ESB-2011.0217

OVERVIEW

        A vulnerability has been corrected in the XNFS server component of
        Novell NetWare 6.5. [1]


IMPACT

        Novell lists the vulnerability as a stack-based buffer overflow that
        does not require authentication to exploit (CVE-2011-4191).
        
        "This vulnerability allows XNFS.NLM's stack buffer to be exceeded by
        certain oversized incoming packets, when the information sent is
        processed by XNFS's xdrDecodeString function. This potentially
        results in processor faults, abends, or execution of arbitary code
        (for example, due to corrupted code pointers in the stack).
        Authentication is not required to exploit this vulnerability.
        A remote attacker can exploit this vulnerability to alter the process's
        instruction pointer, or to abend XNFS processes. After 3 of these
        abends, NFS services become unresponsive." [1]


MITIGATION

        Novell has released a patch (xnfs8d.zip) to correct the vulnerability.
        For instructions on installing the patch as well as details of
        previous patches included in this file visit the Novell website. [1]


REFERENCES

        [1] NetWare XNFS security updates - Nov 2011
            http://download.novell.com/Download?buildid=Cfw1tDezgbw~

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.

===========================================================================
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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