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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== 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 - --------------------------BEGIN INCLUDED TEXT-------------------- SGI IRIX runpriv Design Error Vulnerability iDEFENSE Security Advisory 10.10.05 www.idefense.com/application/poi/display?id=312&type=vulnerabilities October 10, 2005 I. BACKGROUND 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. II. DESCRIPTION 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. III. ANALYSIS 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. 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 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 VI. VENDOR RESPONSE A vendor advisory for this vulnerability is to be posted at: http://www.sgi.com/support/security/advisories.html Vendor patch 7004 for IRIX 6.5.27 and 6.5.28 is available at: http://support.sgi.com/ VII. CVE INFORMATION 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. VIII. DISCLOSURE TIMELINE 09/08/2005 Initial vendor notification 09/09/2005 Initial vendor response 10/05/2005 Coordinated public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp Free tools, research and upcoming events http://labs.idefense.com X. LEGAL NOTICES Copyright (c) 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. 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. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== 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. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBQ0sHsih9+71yA2DNAQLeDAP+NiCLHQDd+HmvJJyQbEwy72SaxLLNuG08 +0d6Vzt2NslJj5NnS+jRxb0iHPnA1g8zWvHO7mZUuhamLURamXN/wf8OHiLycNTW NzLJ/kJIcFwqXLLxuuGH6vrhj6K/a7wrQdvXHOyLQOGD0jOA2VIFdhIWPDKDCe6b LOeqdT5CoXk= =i4bP -----END PGP SIGNATURE-----