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Home » Security Advisories» FreeBSD » Sysinstall bug

Sysinstall bug

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.

  • Vendor: FreeBSD
  • Vendor ID: SA-97:03
  • Date: April 07, 1997


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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: [email protected]
PGP Key: ftp://freebsd.org/pub/CERT/public_key.asc
Security notifications: [email protected]
Security public discussion: [email protected]

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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