SGI IRIX gr_osview File Overwrite Vulnerability 

iDEFENSE Security Advisory 04.07.05
http://www.idefense.com/application/poi/display?type=vulnerabilities
April 7, 2005

I. BACKGROUND

The gr_osview application is a setuid root application that provides a 
graphical display of usage of certain types of operating system 
resources. It is installed by default under multiple versions of IRIX 6.


II. DESCRIPTION

Local exploitation of a file overwrite vulnerability in the gr_osview 
command included in multiple versions of Silicon Graphics Inc.'s IRIX 
operating system could allow for the overwriting of arbitrary files, 
regardless of permissions. 

The vulnerability specifically exists in the way that gr_osview opens 
user specified files without dropping privileges. When a file is 
specified using the "-s" option, it will be opened regardless of 
permissions, and operating system usage information will be written into

it. An example follows: 

user@irix$ gr_osview -s /etc/shadow 

After execution of that command, the system shadow file will be 
overwritten with system usage information. With a damaged shadow file, 
users will no longer be able to log on remotely or locally.

III. ANALYSIS

All that is required to exploit this vulnerability is a local account 
and an open X display, which could be the attacker's home machine or 
another compromised computer. Exploitation does not require any 
knowledge of application internals, making exploitation trivial, even 
for unskilled attackers.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in SGI IRIX 
version 6.5.22 (maintenance). It is suspected that previous and later 
versions of both the feature and maintenance revisions of IRIX 6.5 are 
also vulnerable.

V. WORKAROUND

Only allow trusted users local access to security-critical systems. 
Alternately, remove the setuid bit from inpview using:

chmod u-s /usr/sbin/gr_osview

VI. VENDOR RESPONSE

This vulnerability has been addressed in SGI BUG 930890.

Related security advisories are available at:
   http://www.sgi.com/support/security/advisories.html
   
Related patches are available at:
   http://www.sgi.com/support/security/patches.html
   ftp://patches.sgi.com/support/free/security/patches/

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2005-0465 to these issues. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

02/18/2005  Initial vendor notification
02/23/2005  Initial vendor response
04/07/2005  Coordinated public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright (c) 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.