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===========================================================================
              AUSCERT External Security Bulletin Redistribution

                             
                     ESB-97.041 -- FreeBSD sysinstall bug
                              8 April 1997

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

FreeBSD have issued the following advisory describing a bug in the
sysinstall utility.  Under some circumstances, this will allow unauthorised
access of system resources.

This following security bulletin is provided as a service to AUSCERT's
members.  As AUSCERT did not write this document, AUSCERT has had no
control over its content.  As such, the decision to use any or all of this
information is the responsibility of each user or organisation, and should
be done so in accordance with site policies and procedures.

Contact information for FreeBSD is included in the Security Bulletin
below.  If you have any questions or need further information, please
contact them directly.

If you believe that your system has been compromised, contact AUSCERT or your
representative in FIRST (Forum of Incident Response and Security Teams).

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 4477
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
	AUSCERT personnel answer during Queensland business hours
	which are GMT+10:00 (AEST).
	On call after hours for emergencies.


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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
", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
    +    sprintf(pwline, "%s:*:%s:%d::0:0:%s:%s:/nonexistent
", 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
", FTP_NAME, tconf.uid, gid, tconf.comment, tconf.homedir);
    +   sprintf(pwline, "%s:*:%s:%d::0:0:%s:%s:/nonexistent
", 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@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.
=============================================================================

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