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.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
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There are no warranties with regard to this information. Neither the
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