Mac OS X CF_CHARSET_PATH Buffer Overflow Vulnerability iDEFENSE Security Advisory 03.21.05 www.idefense.com/application/poi/display?id=219&type=vulnerabilities March 21, 2005 I. BACKGROUND Mac OS X is an operating system for the Apple family of microcomputers. More information is available at the following link: http://www.apple.com/macosx/ II. DESCRIPTION Local exploitation of a buffer overflow vulnerability within the Core Foundation Library included by default in Apple Computer Inc.'s Mac OS X could allow an attacker to gain root privileges. The vulnerability specifically exists due to improper handling of the CF_CHARSET_PATH environment variable. When a string greater than 1,024 characters is passed via this variable, a stack-based overflow occurs, allowing the attacker to control program flow by overwriting the function's return address on the stack. Any application linked against the Core Foundation Library can be used as an exploit vector for this vulnerability. Some of the setuid root binaries that are vulnerable include su, pppd and login. III. ANALYSIS Successful exploitation of this vulnerability allows for root access. An attacker needs local access to the victim's system to exploit this vulnerability. This vulnerability is difficult to workaround due to the fact that a large number of system binaries are linked against the vulnerable code. IV. DETECTION iDEFENSE has confirmed this vulnerability in Mac OS X 10.3.5 and Mac OS X 10.3.6. Earlier versions are suspected vulnerable. V. WORKAROUND Restrict local access to trusted users only, as it is impossible to remove the setuid bit from the affected binaries without severely limiting the function of the system. VI. VENDOR RESPONSE This vulnerability is addressed in Apple Security Update 2005-003 available at: http://docs.info.apple.com/article.html?artnum=301061 VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2005-0716 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 02/04/2005 Initial vendor notification 02/04/2005 Initial vendor response 03/21/2005 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@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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