IBM AIX auditselect Local Format String Vulnerability iDEFENSE Security Advisory 02.08.05 www.idefense.com/application/poi/display?id=193&type=vulnerabilities February 08, 2005 I. BACKGROUND The auditselect program is a setuid root application, installed by default under multiple versions of IBM AIX, that selects audit records for analysis according to defined criteria. II. DESCRIPTION Local exploitation of a format string vulnerability in the auditselect 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 improperly used formatted printing function. When provided with an incorrect argument (argv) that contains a format string, the format string will be fed into a formatted printing function, and the user supplied format string will be evaluated, allowing for a malicious user to examine stack memory and write to arbitrary memory locations. With a properly crafted string, this can lead to the execution of arbitrary code. III. ANALYSIS This vulnerability can only be exploited by a local user who has been granted access to the "audit" group. Successful exploitation leads to root-level access. Due to the nature of the vulnerability, information leakage is trivial and aids the attacker in exploitation. 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. IBM has reported that AIX 5.3 is also vulnerable. V. WORKAROUND Only allow trusted users local access to security critical systems. Only allow trusted system administrators access to the "audit" group. Alternately, remove the setuid bit from auditselect using chmod u-s /usr/sbin/auditselect. VI. VENDOR RESPONSE The vendor has not released a patch for this issue, however, the following details have been published: http://www-1.ibm.com/support/docview.wss?uid=isg1IY67519 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 01/07/2005 Initial vendor response 02/08/2005 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.
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