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11 October 2005

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             AUSCERT External Security Bulletin Redistribution

           ESB-2005.0795 -- iDEFENSE Security Advisory 10.10.05
                SGI IRIX runpriv Design Error Vulnerability
                              11 October 2005


        AusCERT Security Bulletin Summary

Product:           runpriv(1M)
Publisher:         iDEFENSE
Operating System:  IRIX
Impact:            Root Compromise
Access:            Existing Account
CVE Names:         CAN-2005-2925

Original Bulletin: http://www.idefense.com/application/poi/display?id=312

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SGI IRIX runpriv Design Error Vulnerability 

iDEFENSE Security Advisory 10.10.05
October 10, 2005


The runpriv program is a setuid root application that checks to see if a
regular user has been granted privileges to execute a certain predefined
command, and if so it runs the command found in the directory 
/usr/sysadm/privbin with root privileges. It is installed by default 
under multiple versions of IRIX 6. 


Local exploitation of a design error vulnerability in the runpriv 
command included in multiple versions of Silicon Graphics Inc.'s IRIX 
could allow for arbitrary code execution as the root user.

The runpriv program is a setuid root application that checks to see if a
regular user has been granted privileges to execute a certain predefined
command, and if so it runs the command found in the directory 
/usr/sysadm/privbin with root privileges. 

The vulnerability specifically exists because runpriv unsafely executes 
commands after it has verified a user's privileges. This allows an 
attacker who has been given privileged access to one binary in 
/usr/sysadm/privbin to effectively execute any command as root. To 
exploit this vulnerability, all that is required is appending a string 
of the form "command to execute" to the end of an otherwise authorized 
and legitimate command. For example, if a user has been authorized to 
run the mountfs utility, they can exploit this vulnerability in the 
following way: 

/usr/sysadm/bin/runpriv mountfs -s test -d / -o \|
  "ksh -c 'echo r00t::0:0:r00t:/tmp:/bin/sh >> /etc/passwd'"
su r00t -c "chown root:sys /tmp/passwd123 ;
mv /tmp/passwd123 /etc/passwd ;
chmod 644 /etc/passwd ; su" 

This will have the effect of adding an administrative user "r00t" to the
system with no password, which allows for trivial privilege escalation.


Exploitation requires an attacker to have access to an account which has
been granted usage of a binary in the /usr/sysadm/privbin directory. As 
root must explicitly allow such privileges, the impact of this 
vulnerability is lessened significantly. Exploitation does not require 
any knowledge of application internals, making exploitation trivial, 
even for unskilled attackers. 


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.


Only grant runpriv privileges to trusted users with secure accounts. 
Alternately, remove the setuid and setgid bits from runpriv: 

chmod ug-s /usr/sysadm/bin/runpriv 


A vendor advisory for this vulnerability is to be posted at:


Vendor patch 7004 for IRIX 6.5.27 and 6.5.28 is available at:



The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2925 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.


09/08/2005  Initial vendor notification
09/09/2005  Initial vendor response
10/05/2005  Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright (c) 2005 iDEFENSE, Inc.

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There are no warranties with regard to this information. Neither the
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or consequential loss or damage arising from use of, or reliance on,
this information.

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