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AA-2001.03                     AUSCERT Advisory

            Sun Microsystems ypbind Buffer Overflow Vulnerability

                                22 June 2001

Last Revised: --

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AusCERT has received information that a vulnerability exists in the program
ypbind for Solaris 8, 7, 2.6, 2.5.1, 2.5, and 2.4 (SunOS 5.8, 5.7,
5.6, 5.5.1, 5.5, and 5.4).

This vulnerability may allow local and/or remote users to gain root
privileges.

AusCERT recommends that sites take the steps outlined in section 3 as soon
as possible.

This advisory will be updated as more information becomes available.

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1.  Description

    ypbind is the daemon that maintains binding information for clients
    and servers that are configured to use NIS.

    A buffer overflow vulnerability exists in ypbind which may be exploited
    by a malicious local or remote user to obtain root access.

    Sun Microsystems has provided the following details of vulnerable and
    non-vulnerable versions of SunOS.

    Vulnerable versions of SunOS are:	5.8, 5.8_x86, 
					5.7, 5.7_x86, 
					5.6, 5.6_x86, 
					5.5.1, 5.5.1_x86, 
					5.5, 5.5_x86, 
					5.4, and 5.4_x86.  

    SunOS 5.8 01/01 and SunOS 5.8_x86 01/01 and all later SunOS 5.8 update
    releases are NOT vulnerable.  SunOS 5.8 and SunOS 5.8_x86 with
    Maintenance Update (MU) 3 or a later MU applied are also NOT
    vulnerable.

    Sites can determine if they are running one of the afore-mentioned
    non-vulnerable versions of SunOS by checking the contents of the
    /etc/release file.

    Vendor patches are available - refer to Section 3 for details.

2.  Impact

    This vulnerability may allow local or remote users to gain root
    privileges.

3.  Solution

    AusCERT recommends that official vendor patches be installed.  Sun
    patches that address this vulnerability are listed below and are
    available at:

	http://sunsolve.sun.com/securitypatch

	OS Version          Patch ID        
    	__________          _________
    	SunOS 5.8           110322-01    
    	SunOS 5.8_x86       110323-01    
    	SunOS 5.7           108750-02    
    	SunOS 5.7_x86       108751-02    
    	SunOS 5.6           105403-04   
    	SunOS 5.6_x86       105404-04    
    	SunOS 5.5.1         105165-04   
    	SunOS 5.5.1_x86     105166-04    
    	SunOS 5.5           105169-04   
    	SunOS 5.5_x86       105170-04    
    	SunOS 5.4           101973-41   
    	SunOS 5.4_x86       101974-41    

    Checksums for these patches are available at:

    	ftp://sunsolve.sun.com/pub/patches/CHECKSUMS

4.0 Vendor Information

    Sun have released security bulletin #00203 regarding this vulnerability
    which is publicly available at the following URL:

	http://sunsolve.sun.com/security

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AusCERT would like to acknowledge the assistance of the Sun Security
Coordination Team as well as Mark Dowd and Stephen James of IT Audit &
Consulting in producing this Advisory.
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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
appropriateness of this document for an organisation or individual system
should be considered before application in conjunction with local policies
and procedures.  AusCERT takes no responsibility for the consequences of
applying the contents of this document.

If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security
Teams).

AusCERT maintains an anonymous FTP service which is found on:
ftp://ftp.auscert.org.au/pub/.  This archive contains past SERT and AusCERT
Advisories, and other computer security information.

AusCERT also maintains a World Wide Web service which is found on:
http://www.auscert.org.au/.

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 emergencies.

Postal:
Australian Computer Emergency Response Team
The University of Queensland
Brisbane        
Qld  4072     
AUSTRALIA       


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Revision History


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