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NSFOCUS Security Advisory(SA2003-02)

Topic: Solaris lpq Stack Buffer Overflow Vulnerability

Release Date: 2003-3-31 

CVE CAN ID: CAN-2003-0091

Affected system:
===================

Sun Solaris 2.5.1 (SPARC/x86)
Sun Solaris 2.6 (SPARC/x86)
Sun Solaris 7   (SPARC/x86)
                                                               
Summary:
=========

NSFOCUS Security Team has found a buffer overflow vulnerability in lpq, an 
application in Sun Solaris system. Exploiting the vulnerability local 
attackers could gain root privilege.  

Description:
============

lpq, which is used to display the contents in printing queue, is a command 
in SunOS/BSD compatible package.By default suid root bit is set to it. 
Because valid bound check has not been implemented when handling the data 
provided by users, attackers could cause a fixed stack buffer to overflow.
By carefully crafting overflow data attackers could run arbitrary code with 
root privilege. 

Actually /usr/ucb/lpq is a symbol link to /usr/bin/lpstat. lpstat will 
operate according to the program names during the calling. If "lpq", it will
operate in BSD style, or it will operate in System V style. The bsd_queue()
function in lpq will call strcat() to copy the data provided by users to a 
buffer the size of which is fixed. Because the length of the copied data has
not been checked, if an attacker provides a over-long string, he/she will
cause a stack buffer overflow. By overwriting the returning addresses and other
data in the stack, local attackers could gain root privilege. 

Solaris 8/9 uses strlcat() to implement string copy, so it avoids buffer
overflow and therefore is not vulnerable to the issue.  

Workaround:
=============

 NSFOCUS suggests to disable suid root attribute of lpstat(lpq) temporarily:
 # chmod a-s /usr/bin/lpstat

Vendor Status:
==============

2002-12-11  Informed the vendor.
2002-12-13  The vendor confirmed the vulnerability. 
2003-03-31  The vendor released a Sun Alert and patches for this issue. 

The Sun Alert is available at:
http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/52443

The patches are:

Solaris 2.6     106235-12
Solaris 2.6_x86 106236-12
Solaris 7       107115-12
Solaris 7_x86   107116-12


Additional Information:
========================

The Common Vulnerabilities and Exposures (CVE) project has assigned the 
name CAN-2003-0091 to this issue. This is a candidate for inclusion in the
CVE list (http://cve.mitre.org), which standardizes names for security 
problems. Candidates may change significantly before they become official 
CVE entries.

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==========
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Copyright 1999-2003 NSFOCUS. All Rights Reserved. Terms of use.


NSFOCUS Security Team <security@nsfocus.com>
NSFOCUS INFORMATION TECHNOLOGY CO.,LTD
(http://www.nsfocus.com)

PGP Key: http://www.nsfocus.com/homepage/research/pgpkey.asc
Key fingerprint = F8F2 F5D1 EF74 E08C 02FE  1B90 D7BF 7877 C6A6 F6DA

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