[Full-Disclosure] iDEFENSE Security Advisory 02.10.05: IBM AIX ipl_varyon Local Buffer Overflow Vulnerability

idlabs-advisories_at_idefense.com
Date: 02/10/05

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    Date: Thu, 10 Feb 2005 11:00:17 -0500
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    IBM AIX ipl_varyon Local Buffer Overflow Vulnerability

    iDEFENSE Security Advisory 02.10.05
    www.idefense.com/application/poi/display?id=196&type=vulnerabilities
    February 10, 2005

    I. BACKGROUND

    The ipl_varyon program is a setuid root application, installed by
    default under multiple versions of IBM AIX, which can be used to set the

    default physical boot volume.

    II. DESCRIPTION

    Local exploitation of a buffer overflow vulnerability in the ipl_varyon
    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 unbounded
    string copy operation. When provided with a long argument to the -d
    option, the ipl_varyon process will overwrite stack memory with the user

    supplied string. This allows for overwriting of the saved return address

    on the stack, which in turn allows for complete control over execution
    flow.

    III. ANALYSIS

    Exploitation of this vulnerability is simple for a skilled attacker,
    however gid "system" is required in order to execute the vulnerable
    binary. Successful exploitation yields root access on the system.

    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.

    V. WORKAROUND

    Only allow trusted users local access to security critical systems; only

    allow trusted users access to the "system" group. Alternately, remove
    the setuid bit from netpmon using chmod u-s /usr/sbin/ipl_varyon

    VI. VENDOR RESPONSE

    Vendor advisories for this issue are available at:

    For AIX 5.1:

    https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
    e=1&heading=AIX51&topic=SECURITY&month=ALL

    For AIX 5.2:

    https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
    e=1&heading=AIX52&topic=SECURITY&month=ALL

    For AIX 5.3:

    https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
    e=1&heading=AIX53&topic=SECURITY&month=ALL

    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
    01/07/2004 Initial vendor response
    02/10/2004 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) 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@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.

    _______________________________________________
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