Conference minotr::security_advisory

148.0. "Information Only: CIAC H59, Solaris Buffr ovrflw" by MINOTR::NOBLE (Your Data, Your Job...Protect Both) Thu May 29 1997 08:33

    The DIGITAL Corporate Information Security Group has received the
    following external security notice.  It should be noted that DIGITAL
    does not support the software identified, nor have the reported
    problems been verified by DIGITAL.
    
    This third party notice is being provided as information only.  No
    security action is required.  Nor is any recommendation being made with
    regards the solution(s) identified.
    
    Should you happen to be using the third party software impacted by
    this notice, please use due discretion before implementing any or all
    of the solution(s) identified.
    
    If you are an internal user of the software impacted in this notice,
    and have any questions regarding this notice, then please contact your
    IT Cluster Security Manager.  An up-to-date list can be found at URL
    http://www-is-security.mso.dec.com/
      
                                  -=<>=-
    

    
    
    
             __________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

              Solaris 2.x Buffer Overflow Vulnerabilities (ps, chkey)

May 22, 1997 17:00 GMT                                             Number H-59
______________________________________________________________________________
PROBLEM:       Two buffer overflow vulnerabilities have been identified:
                 1) ps(1) program
                 2) chkey(1) program
PLATFORM:      All platforms with Solaris 2.x
DAMAGE:        These vulnerabilities may allow local users to gain root
               privileges.
SOLUTION:      Until patches are available, take the steps outlined in Section
               3 of each advisory as soon as possible.
______________________________________________________________________________
VULNERABILITY  Exploit details involving these vulnerabilities have been made
ASSESSMENT:    publicly available.
______________________________________________________________________________

[ Start AUSCERT Advisories ]

1) ps(1) program
===========================================================================
AA-97.17                        AUSCERT Advisory
                 Solaris 2.x ps Buffer Overflow Vulnerability
                                  21 May 1997

Last Revised:  

-
-----------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
ps(1) program under Solaris 2.x.

This vulnerability may allow local users to gain root privileges.

Exploit information involving this vulnerability has been made publicly
available.

Currently there are no vendor patches available that address this
vulnerability.  AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.

This advisory will be updated as more information becomes available.
-
-----------------------------------------------------------------------------

1.  Description

    AUSCERT has received information that a vulnerability exists in the
    Solaris 2.x ps(1) program. 

    ps is a program used to print information about active processes on
    the system.

    Due to insufficient bounds checking on arguments passed to the ps
    program, it is possible to overwrite the internal data space of this
    program while it is executing. This vulnerability may allow local
    users to gain root privileges.

    Exploit information involving this vulnerability has been made publicly
    available.

    Under Solaris 2.x there are two distinct vulnerable versions of ps.
    These are installed by default in /usr/bin/ and /usr/ucb/.

    Sun Microsystems is aware of this problem and is currently
    investigating it.

2.  Impact

    Local users may gain root privileges.

3.  Workarounds/Solution

    AUSCERT recommends that sites limit the possible exploitation of this
    vulnerability by immediately applying the workaround given in Section
    3.1.

    To maintain the functionality of ps, AUSCERT recommends applying the
    workaround given in Section 3.2.

    Currently there are no vendor patches available that address this
    vulnerability.  AUSCERT recommends that official vendor patches be
    installed when they are made available.

3.1 Remove setuid and non-root execute permissions

    To prevent the exploitation of the vulnerability described in this
    advisory, AUSCERT recommends that the setuid permissions be removed
    from ps program immediately.  As the ps program will no longer work
    for non-root users, it is recommended that the execute permissions
    for them also be removed.

        # ls -l /usr/bin/ps /usr/ucb/ps
        -r-sr-xr-x   1 root   sys      23752 Oct 25  1995 /usr/bin/ps
        -rwsr-xr-x   1 root   sys      23408 Oct 25  1995 /usr/ucb/ps

        # chmod 500 /usr/bin/ps /usr/ucb/ps

        # ls -l /usr/bin/ps /usr/ucb/ps
        -r-x------   1 root   sys      23752 Oct 25  1995 /usr/bin/ps
        -r-x------   1 root   sys      23408 Oct 25  1995 /usr/ucb/ps

3.2 Install wrapper

    AUSCERT has developed a wrapper to help prevent programs from being
    exploited using the vulnerability described in this advisory.  Sites
    which have a C compiler can obtain the source, compile and install
    the wrapper as described in Section 3.2.1. For sites without a C
    compiler, AUSCERT has made pre-compiled binaries available for Solaris
    2.4, 2.5 and 2.5.1 (Section 3.2.2).

3.2.1 Installing the wrapper from source

    The source for the wrapper, including installation instructions, can
    be obtained from:

        ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/
                                                overflow_wrapper.c

    This wrapper replaces the ps program and checks the length of the
    command line arguments which are passed to it.  If an argument exceeds
    a certain predefined value (MAXARGLEN), the wrapper exits without
    executing the ps command.  The wrapper program can also be configured
    to syslog any failed attempts to execute ps with arguments exceeding
    MAXARGLEN.  For further instructions on using this wrapper, please
    read the comments at the top of overflow_wrapper.c.

    The wrapper will need to be applied to both ps programs on the system
    (/usr/bin/ps and /usr/ucb/ps).

    When compiling overflow_wrapper.c for use with ps, AUSCERT recommends
    defining MAXARGLEN to be 32.

    The MD5 checksum for the current version of overflow_wrapper.c can be
    retrieved from:

        ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/CHECKSUM

    The CHECKSUM file has been digitally signed using the AUSCERT PGP key.

3.2.2 Installing the wrapper binaries

    Pre-compiled wrapper binaries are provided for sites that wish to
    install the wrapper but do not have a C compiler available.  AUSCERT
    has compiled the wrapper on Solaris 2.4, 2.5 and 2.5.1.  The following
    compile time options have been used to the create the binaries:

         REAL_PROG='"/usr/bin/ps.real"'
         MAXARGLEN=32
         SYSLOG

    and

         REAL_PROG='"/usr/ucb/ps.real"'
         MAXARGLEN=32
         SYSLOG

    More information on these options can be found in Section 3.2.1 and
    in the overflow_wrapper.c source code.

    The pre-compiled binaries for the wrapper program can be retrieved
    from:

        ftp://ftp.auscert.org.au/pub/auscert/tools/ps_wrapper.tar.Z

    The MD5 checksum for ps_wrapper.tar.Z is:

        MD5 (ps_wrapper.tar.Z) = 6c0a9a2739561aba5968fc54b10d8c32

    ps_wrapper.tar.Z contains a README file with installation instructions,
    as well as pre-compiled binaries for /usr/bin/ps and /usr/ucb/ps under
    Solaris 2.4, 2.5 and 2.5.1. The binaries have been linked statically
    so they are larger than the default ps binary.

    Sites are encouraged to carefully read the installation notes in the
    README file before installation.
===========================================================================


2) chkey(1) program
===========================================================================
AA-97.18                        AUSCERT Advisory
                 Solaris 2.x chkey Buffer Overflow Vulnerability
                                  22 May 1997

Last Revised:  

-
-----------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
chkey(1) program under Solaris 2.x.

This vulnerability may allow local users to gain root privileges.

Exploit information involving this vulnerability has been made publicly
available.

Currently there are no vendor patches available that address this
vulnerability.  AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.

This advisory will be updated as more information becomes available.
-
-----------------------------------------------------------------------------

1.  Description

    AUSCERT has received information that a vulnerability exists in the
    Solaris 2.x chkey(1) program.

    chkey is used to change a user's secure RPC public key and secret key
    pair.

    Due to insufficient bounds checking on arguments passed to the chkey
    program, it is possible to overwrite the internal data space of this
    program while it is executing. As chkey has setuid root permissions,
    this vulnerability may allow local users to gain root privileges.

    Exploit information involving this vulnerability has been made publicly
    available.

    chkey under Solaris 2.x is located by default in /usr/bin/.

    Sun Microsystems is aware of this problem and is currently
    investigating it.

2.  Impact

    Local users may gain root privileges.

3.  Workarounds/Solution

    AUSCERT recommends that sites limit the possible exploitation of this
    vulnerability by immediately applying the workaround given in Section
    3.1.

    To maintain the functionality of chkey, AUSCERT recommends applying
    the workaround given in Section 3.2.

    Currently there are no vendor patches available that address this
    vulnerability.  AUSCERT recommends that official vendor patches be
    installed when they are made available.

3.1 Remove setuid and non-root execute permissions

    To prevent the exploitation of the vulnerability described in this
    advisory, AUSCERT recommends that the setuid permissions be removed
    from the chkey program immediately.  As the chkey program will no
    longer work for non-root users, it is recommended that the execute
    permissions for them also be removed.

        # ls -l /usr/bin/chkey
        -r-sr-xr-x   1 root   sys      19608 Oct 25  1995 /usr/bin/chkey

        # chmod 500 /usr/bin/chkey

        # ls -l /usr/bin/chkey
        -r-x------   1 root   sys      19608 Oct 25  1995 /usr/bin/chkey

    For those sites which require the chkey functionality, AUSCERT
    recommends applying the workaround given in Section 3.2.

3.2 Install wrapper

    AUSCERT has developed a wrapper to help prevent programs from being
    exploited using the vulnerability described in this advisory.  Sites
    which have a C compiler can obtain the source, compile and install
    the wrapper as described in Section 3.2.1. For sites without a C
    compiler, AUSCERT has made pre-compiled binaries available for Solaris
    2.4, 2.5 and 2.5.1 (Section 3.2.2).

3.2.1 Installing the wrapper from source

    The source for the wrapper, including installation instructions, can
    be obtained from:

        ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/
                                                overflow_wrapper.c

    This wrapper replaces the chkey program and checks the length of the
    command line arguments which are passed to it.  If an argument exceeds
    a certain predefined value (MAXARGLEN), the wrapper exits without
    executing the chkey command.  The wrapper program can also be
    configured to syslog any failed attempts to execute chkey with
    arguments exceeding MAXARGLEN.  For further instructions on using this
    wrapper, please read the comments at the top of overflow_wrapper.c.

    When compiling overflow_wrapper.c for use with chkey, AUSCERT recommends
    defining MAXARGLEN to be 32.

    The MD5 checksum for the current version of overflow_wrapper.c can be
    retrieved from:

        ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/CHECKSUM

    The CHECKSUM file has been digitally signed using the AUSCERT PGP key.

3.2.2 Installing the wrapper binaries

    Pre-compiled wrapper binaries are provided for sites that wish to
    install the wrapper but do not have a C compiler available.  AUSCERT
    has compiled the wrapper on Solaris 2.4, 2.5 and 2.5.1.  The following
    compile time options have been used to the create the binaries:

         REAL_PROG='"/usr/bin/chkey.real"'
         MAXARGLEN=32
         SYSLOG

    More information on these options can be found in Section 3.2.1 and
    in the overflow_wrapper.c source code.

    The pre-compiled binaries for the wrapper program can be retrieved
    from:

       
ftp://ftp.auscert.org.au/pub/auscert/tools/AA-97.18-chkey_wrapper.tar.Z

    The MD5 checksum for AA-97.18-chkey_wrapper.tar.Z is:

        MD5 (AA-97.18-chkey_wrapper.tar.Z) = bafd43c2357156595d65c7ed38fd6aeb

    AA-97.18-chkey_wrapper.tar.Z contains a README file with installation
    instructions, as well as pre-compiled binaries for /usr/bin/chkey
    under Solaris 2.4, 2.5 and 2.5.1. The binaries have been linked
    statically so they are larger than the default chkey binary.

    Sites are encouraged to carefully read the installation notes in the
    README file before installation.

===========================================================================


[ End AUSCERT Advisories ]

______________________________________________________________________________

CIAC wishes to acknowledge the contributions of AUSCERT and Nelson Marques
(The University of Queensland) for the information contained in this bulletin.
Thanks also to the Department of Mathematics(The University of Queensland) for
providing temporary test equipment.
______________________________________________________________________________


CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.

This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
owned rights. Reference herein to any specific commercial products,
process, or service by trade name, trademark, manufacturer, or
otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.