IBM AIX ctstrtcasd Local File Corruption Vulnerability iDEFENSE Security Advisory 09.27.04 www.idefense.com/application/poi/display?id=144&type=vulnerabilities September 27, 2004 I. BACKGROUND The ctstrtcasd program is a setuid root application, installed by default under newer versions of IBM AIX. It is part of the Reliable Scalable Cluster Technology (RSCT) system. It is also installed with multiple IBM products under Linux, including IBM Tivoli System Automation, IBM Cluster Systems Management, IBM Hardware Management Console, and IBM General Parallel File System. II. DESCRIPTION Local exploitation of an input validation vulnerability in the ctstrtcasd command included by default in multiple versions of IBM Corp. AIX could allow for the corruption or creation of arbitrary files anywhere on the system. If a user specifies a file with the -f option, the contents of that file will be overwritten with 65,535 bytes of application trace data. If the file doesn't exist, it will be created. The file creation/overwrite is done with root privileges, thus allowing an attacker to cause a denial of service condition by damaging the file system or by filling the drive with 65,535 byte files. III. ANALYSIS All that is required to exploit this vulnerability is a local account. Exploitation does not require any knowledge of application internals, making exploitation trivial, even for unskilled attackers. It is not evident that privilege escalation is possible through abuse of this. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in IBM AIX 5.2. IBM has reported that RSCT versions 2.3.0.0 and greater are affected, for AIX 5.2 and 5.3 on pSeries; AIX on i5/OS (iSeries); RSCT on Linux (pSeries, xSeries, zSeries), and the pSeries Hardware Management Console. Products shipping and installing these affected versions of RSCT as reported by IBM are as follows: IBM AIX 5L Version 5.2 on pSeries IBM AIX 5L Version 5.3 on pSeries IBM AIX 5L Version 5.2, 5.3 on an i5/OS (iSeries) partition IBM Tivoli System Automation (TSA) for Linux 1.1 IBM Tivoli System Automation (TSA) for Multiplatforms 1.2 IBM Cluster Systems Management (CSM) for Linux Version 1.4 (version 1.4 and greater) IBM Hardware Management Console (HMC) for pSeries Version 3 IBM Hardware Management Console (HMC) for pSeries Version 4 IBM General Parallel File System (GPFS) Version 2 Release 2 on Linux for xSeries and Linux for pSeries V. WORKAROUND Only allow trusted users local access to security critical systems. Alternately, remove the setuid bit from ctstrtcasd using chmod 555 /usr/sbin/rsct/bin/ctstrtcasd. VI. VENDOR RESPONSE "Apply the workarounds or APARs as described [in the associated IBM Security Alert]. If you would like to receive AIX Security Advisories via email, please visit: https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs" VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the names CAN-2004-0828 to these issues. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 08/11/2004 Initial vendor notification 08/25/2004 Secondary vendor notification 08/26/2004 Vendor response 09/27/2004 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) 2004 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.