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From: FreeBSD Security Advisories (security-advisoriesFreeBSD.org)
Date: Thu Apr 19 2001 - 14:11:55 CDT

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    =============================================================================
    FreeBSD-SA-01:33 Security Advisory
                                                                    FreeBSD, Inc.

    Topic: globbing vulnerability in ftpd [REVISED]

    Category: core
    Module: ftpd/libc
    Announced: 2001-04-17
    Revised: 2001-04-19
    Credits: John McDonald and Anthony Osborne, COVERT Labs
    Affects: FreeBSD 3.x (all releases), FreeBSD 4.x (all releases),
                    FreeBSD 3.5-STABLE and 4.3-RC prior to the
                    correction date.
    Corrected: 2001-04-17 (FreeBSD 4.3-RC)
                    2001-04-17 (FreeBSD 3.5-STABLE)
    Vendor status: Corrected
    FreeBSD only: NO

    0. Revision History

    2001-04-17 v1.0 Initial release
    2001-04-19 v1.1 Corrected patch and patch instructions

    I. Background

    Numerous FTP daemons, including the daemon distributed with FreeBSD,
    use server-side globbing to expand pathnames via user input. This
    globbing is performed by FreeBSD's glob() implementation in libc.

    II. Problem Description

    The glob() function contains potential buffer overflows that may be
    exploitable through the FTP daemon. If a directory with a name of
    a certain length is present, a remote user specifying a pathname
    using globbing characters may cause arbitrary code to be executed
    on the FTP server as user running ftpd, usually root.

    Additionally, when given a path containing numerous globbing
    characters, the glob() functions may consume significant system
    resources when expanding the path. This can be controlled by
    setting user limits via /etc/login.conf and setting limits on
    globbing expansion.

    All versions of FreeBSD prior to the correction date, including
    FreeBSD 3.5.1 and 4.2 contain this problem. The base system that
    will ship with FreeBSD 4.3 does not contain this problem since it
    was corrected before the release.

    III. Impact

    Remote users may be able to execute arbitrary code on the FTP server
    as the user running ftpd, usually root.

    The FTP daemon supplied with FreeBSD is enabled by default to allow
    access to authorized local users and not anonymous users, thus
    limiting the impact to authorized local users.

    IV. Workaround

    If the FTP daemon is executed from inetd, disable the FTP daemon by
    commenting out the ftp line in /etc/inetd.conf, then reload the
    inetd configuration by executing the following command as root:

    # killall -HUP inetd

    V. Solution

    One of the following:

    1) Upgrade to FreeBSD 4.3-RC or 3.5.1-STABLE after the correction
    date.

    2) Download the patch and detached PGP signature from the following
    location:

    The following patch applies to FreeBSD 4.x:

    # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.4.x.patch
    # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.4.x.patch.asc

    The following patch applies to FreeBSD 3.x:

    # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.3.x.patch
    # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.3.x.patch.asc

    Verify the detached signature using your PGP utility.

    Issue the following commands as root:

    # cd /usr/src
    # patch -p < /path/to/patch
    # cp /usr/src/include/glob.h /usr/include/
    # cd /usr/src/lib/libc
    # make all install
    # cd /usr/src/libexec/ftpd
    # make all install

    If the FTP daemon is running standalone, it will have to be manually
    stopped and restarted.
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