From aleph1@DFW.NET Thu Mar 27 18:45:08 1997
Date: Wed, 26 Mar 1997 16:59:12 -0600
From: Aleph One <aleph1@DFW.NET>
To: BUGTRAQ@NETSPACE.ORG
Subject: FreeBSD-SA-97:02: Buffer overflow in lpd

-----BEGIN PGP SIGNED MESSAGE-----

=============================================================================
FreeBSD-SA-97:02                                            Security Advisory
                                                                FreeBSD, Inc.

Topic:          Buffer overflow in lpd

Category:       core
Module:         lpd
Announced:      1997-03-xxx
Affects:        FreeBSD 2.1.7 and earlier and FreeBSD 2.2 snapshots
                before 1997/02/25 suffer from this problem.
Corrected:      FreeBSD-current as of 1997/02/25
                FreeBSD 2.2 as of 1997/02/25
FreeBSD only:   yes

Patches:        ftp://freebsd.org/pub/CERT/patches/SA-97:02/

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

I.   Background

     The lpd program is used to print local and remote print jobs.  It
     is standard software in the FreeBSD operating system.

II.  Problem Description

     The lpd program runs as root.  A remote attacker can exploit a
     buffer overflow to obtain root privs.

III. Impact

     Remote users can gain root privs.

IV.  Workaround

     The only workaround is to disable lpd, which will have the effect
     of removing the printing functionality from the system.  Since
     the buffer overflow happens before the connection is authenticated,
     using lpd's authentication methods will not affect the system
     vulnerability.

V.   Solution

     Apply the following patch, rebuild and install libc:

     (This patch can also be found on
        ftp://freebsd.org/pub/CERT/patches/SA-97:02/)

    Index: rcmd.c
    ===================================================================
    RCS file: /home/imp/FreeBSD/CVS/src/lib/libc/net/rcmd.c,v
    retrieving revision 1.3.4.4
    retrieving revision 1.3.4.5
    diff -u -r1.3.4.4 -r1.3.4.5
    --- rcmd.c  1997/02/09 06:57:54     1.3.4.4
    +++ rcmd.c  1997/02/26 06:14:11     1.3.4.5
    @@ -377,7 +377,8 @@
        if ((hp = gethostbyaddr((char *)&raddr, sizeof(u_long),
                                                        AF_INET)) == NULL)
                return (-1);
    -   strcpy(hname, hp->h_name);
    +   strncpy(hname, hp->h_name, sizeof(hname));
    +   hname[sizeof(hname) - 1] = '\0';

        while (fgets(buf, sizeof(buf), hostf)) {
                p = buf;

VI.   Thanks

     This problem was brought to light by Oliver Friedrichs
     <oliver@SECNET.COM>.

=============================================================================
FreeBSD, Inc.

Web Site:                       http://www.freebsd.org/
Confidential contacts:          security-officer@freebsd.org
PGP Key:                        ftp://freebsd.org/pub/CERT/public_key.asc
Security notifications:         security-notifications@freebsd.org
Security public discussion:     security@freebsd.org

Notice: Any patches in this document may not apply cleanly due to
        modifications caused by digital signature or mailer software.
        Please reference the URL listed at the top of this document
        for original copies of all patches if necessary.
=============================================================================

-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQCVAwUBMzmOqlUuHi5z0oilAQH1hAP/fSVklicjFNo4hLVO2dYLLiIPnB9uVWNl
ocC2Ozu1sX6SH3Kz688QlTEnyDzjshkisI9nr+947A/CjwJDPwqQRbqmbAdI+qka
HNQJmVQYWW2J6j70SJX8q0z1uQHoNsJB7VStQ1VX+4BD91CsjBr3lrU5xFyjqxYt
uJMeNl0sa9A=
=agxY
-----END PGP SIGNATURE-----