SunOS :Buffer overflow vulnerability in "ps"

The attached advisory describes a security vulnerability in the "ps"
program on Sun Solaris 2.x.

Some hosts were not fixed, because a problem was encountered
while applying the relevant patch.  If you have a "regular" or "high"
support contract with us, we'll be fixing this for you soon.

[This notice is a part of OAC's efforts to keep the campus informed of
potential computer security liabilities.  Please send any questions or
concerns to us at DCS@UCI.EDU]

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.