SCO Openserver authsh 'Home' Buffer Overflow Vulnerability iDEFENSE Security Advisory 10.24.05 http://www.idefense.com/application/poi/display?type=vulnerabilities October 24, 2005 I. BACKGROUND SCO OpenServer is a UNIX-like operating system for x86 platforms. II. DESCRIPTION Local exploitation of a buffer overflow vulnerability in The SCO Group Inc.'s Openserver operating system could allow an attacker to gain root privileges. The authsh utility is a standard binary distributed with the Openserver platform. The vulnerability specifically exists because of a lack of bounds checking on the value given to the "HOME" environment variable. Local attackers can supply a specially crafted string to overflow a stack buffer and execute arbitrary code with group auth privileges. III. ANALYSIS Successful exploitation of this vulnerability will result in execution of arbitrary code with permissions of the running process. The binary is setgid auth by default and can be used by attackers with a local account to gain root privileges, as the group auth has write access to system authentication information. An attacker would only need to modify the system passwd file to grant an account they control superuser privileges. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in SCO Openserver 5.0.7. It is suspected that earlier versions are also vulnerable. V. WORKAROUND As a workaround solution, remove the setgid bit from the authsh binary until a vendor patch can be applied. # chmod -g /opt/K/SCO/Unix/5.0.7Hw/usr/lib/sysadm/authsh VI. VENDOR RESPONSE The vendor has released the following advisory for this issue: ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2005.40/SCOSA-2005.40.txt VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2005-2926 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 10/24/2005 Public disclosure IX. CREDIT iDEFENSE Labs is credited with the discovery of this vulnerability. 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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