FreeBSD Security Advisory: FreeBSD-SA-97:03.sysinstall

[Jonathan M. Bresler]

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=============================================================================
FreeBSD-SA-97:03                                            Security Advisory
                                                            FreeBSD, Inc.

Topic:          sysinstall bug

Category:       core
Module:         sysinstall
Announced:      1997-04-07
Affects:        FreeBSD 2.1, FreeBSD 2.1.5, FreeBSD 2.1.6 and FreeBSD 2.1.7
                FreeBSD 2.2 and FreeBSD 2.2.1.

Corrected:      all versions as of 1997-04-01. This includes the installation                   floppies for FreeBSD 2.2.1 found on:
                ftp://ftp.FreeBSD.org/pub/FreeBSD/2.2.1-RELEASE/floppies/newer/
                Also the CDROM of FreeBSD 2.2.1 has this problem corrected.
Source:         FreeBSD
FreeBSD only:   yes

Patches:        

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

I.   Background

     Sysinstall is used both for fresh installations of FreeBSD as
     well as post installation updates, like installing packages
     from CDROM or ftp sites.

II.  Problem Description

     One of the port installation options in sysinstall is to install
     an anonymous ftp setup on the system. In such a setup, an extra
     user needs to be created on the system, with username 'ftp'.
     This user is created with the shell equal to '/bin/date' and an
     empty password.

III. Impact

     Under some circumstances, this will allow unauthorized access
     of system resources.

IV. Solution(s)

     Change the entry of the ftp user such that is has an invalid password
     and an invalid shell. This can be done by becoming the superuser,
     and use the vipw command. Go to the line that starts with ftp::
     and change ftp:: to ftp:*: 
     Also change, on the same line, the shell from /bin/date to /nonexistent.

     If you have not yet used sysinstall to create an anonymous ftp setup,
     but are planning to, please apply one of the following patches:

     Patch for FreeBSD 2.1.5, 2.1.6, 2.2 and 2.2.1:

    --- anonFTP.c       1996/04/28 03:26:42     1.14
    +++ anonFTP.c       1997/04/07 17:20:16
    @@ -195,7 +195,7 @@
        return (DITEM_SUCCESS);         /* succeeds if already exists */
         }
         
    -    sprintf(pwline, "%s::%s:%d::0:0:%s:%s:/bin/date\n", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
    +    sprintf(pwline, "%s:*:%s:%d::0:0:%s:%s:/nonexistent\n", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
         
         fptr = fopen(_PATH_MASTERPASSWD,"a");
         if (! fptr) {

    Patch for FreeBSD 2.1:
    
    --- anonFTP.c       1995/11/12 07:27:55     1.6
    +++ anonFTP.c       1997/04/03 19:29:21
    @@ -201,7 +201,7 @@
         return (RET_SUCCESS);  /* succeeds if already exists */
        }
     
    -   sprintf(pwline, "%s::%s:%d::0:0:%s:%s:/bin/date\n", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
    +   sprintf(pwline, "%s:*:%s:%d::0:0:%s:%s:/nonexistent\n", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
     
        fptr = fopen(_PATH_MASTERPASSWD,"a");
        if (! fptr) {

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

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

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