IBM AIX ipl_varyon Local Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.10.05 www.idefense.com/application/poi/display?id=196&type=vulnerabilities February 10, 2005 I. BACKGROUND The ipl_varyon program is a setuid root application, installed by default under multiple versions of IBM AIX, which can be used to set the default physical boot volume. II. DESCRIPTION Local exploitation of a buffer overflow vulnerability in the ipl_varyon command included by default in multiple versions of IBM Corp.'s AIX Operating System could allow for arbitrary code execution as the root user. The vulnerability specifically exists due to an unbounded string copy operation. When provided with a long argument to the -d option, the ipl_varyon process will overwrite stack memory with the user supplied string. This allows for overwriting of the saved return address on the stack, which in turn allows for complete control over execution flow. III. ANALYSIS Exploitation of this vulnerability is simple for a skilled attacker, however gid "system" is required in order to execute the vulnerable binary. Successful exploitation yields root access on the system. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in IBM AIX version 5.2. It is suspected that previous versions are also vulnerable. V. WORKAROUND Only allow trusted users local access to security critical systems; only allow trusted users access to the "system" group. Alternately, remove the setuid bit from netpmon using chmod u-s /usr/sbin/ipl_varyon VI. VENDOR RESPONSE Vendor advisories for this issue are available at: For AIX 5.1: https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod e=1&heading=AIX51&topic=SECURITY&month=ALL For AIX 5.2: https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod e=1&heading=AIX52&topic=SECURITY&month=ALL For AIX 5.3: https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod e=1&heading=AIX53&topic=SECURITY&month=ALL VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. VIII. DISCLOSURE TIMELINE 12/21/2004 Initial vendor notification 01/07/2004 Initial vendor response 02/10/2004 Coordinated public disclosure IX. CREDIT iDEFENSE Labs is credited with this discovery Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp 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@private 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.
This archive was generated by hypermail 2.1.3 : Thu Feb 10 2005 - 10:21:42 PST