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CA-2001-30 Multiple Vulnerabilities in lpd

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CERT Advisory CA-2001-30 Multiple Vulnerabilities in lpd

Original release date: November 05, 2001
Last revised: --
Source: CERT/CC

A complete revision history can be found at the end of this file.

Systems Affected

* BSDi BSD/OS Version 4.1 and earlier
* Debian GNU/Linux 2.1 and 2.1r4
* FreeBSD All released versions FreeBSD 4.x, 3.x, FreeBSD
4.3-STABLE, 3.5.1-STABLE prior to the correction date
* Hewlett-Packard HP9000 Series 700/800 running HP-UX releases
10.01, 10.10, 10.20, 11.00, and 11.11
* IBM AIX Versions 4.3 and AIX 5.1
* Mandrake Linux Versions 6.0, 6.1, 7.0, 7.1
* NetBSD 1.5.2 and earlier
* OpenBSD Version 2.9 and earlier
* Red Hat Linux 6.0 all architectures
* SCO OpenServer Version 5.0.6a and earlier
* SGI IRIX 6.5-6.5.13
* Sun Solaris 8 and earlier
* SuSE Linux Versions 6.1, 6.2, 6.3, 6.4, 7.0, 7.1, 7.2

Overview

There are multiple vulnerabilities in several implementations of the
line printer daemon (lpd). The line printer daemon enables various
clients to share printers over a network. Review your configuration to
be sure you have applied all relevant patches. We also encourage you
to restrict access to the lpd service to only authorized users.

I. Description

There are multiple vulnerabilities in several implementations of the
line printer daemon (lpd), affecting several systems. Some of these
problems have been publicly disclosed previously. However, we believe
many system and network administrators may have overlooked one or more
of these vulnerabilities. We are issuing this document primarily to
encourage system and network administators to check their systems for
exposure to each of these vulnerabilities, even if they have addressed
some lpd vulnerabilities recently.

Most of these vulnerabilities are buffer overflows allowing a remote
intruder to gain root access to the lpd server. For the latest and
most detailed information about the known vulnerabilities, please see
the vulnerability notes linked to below.

VU#274043 - BSD line printer daemon buffer overflow in displayq()

There is a buffer overflow in several implementations of in.lpd, a BSD
line printer daemon. An intruder can send a specially crafted print
job to the target and then request a display of the print queue to
trigger the buffer overflow. The intruder may be able use this
overflow to execute arbitrary commands on the system with superuser
privileges.

The line printer daemon must be enabled and configured properly in
order for an intruder to exploit this vulnerability. This is, however,
trivial as the line printer daemon is commonly enabled to provide
printing functionality. In order to exploit the buffer overflow, the
intruder must launch his attack from a system that is listed in the
"/etc/hosts.equiv" or "/etc/hosts.lpd" file of the target system.

VU#388183 - IBM AIX line printer daemon buffer overflow in
kill_print()

A buffer overflow exists in the kill_print() function of the line
printer daemon (lpd) on AIX systems. An intruder could exploit this
vulnerability to obtain root privileges or cause a denial of service
(DoS). The intruder would need to be listed in the victim's
/etc/hosts.lpd or /etc/hosts.equiv file, however, to exploit this
vulnerability.

VU#722143 - IBM AIX line printer daemon buffer overflow in
send_status()

A buffer overflow exists in the send_status() function of the line
printer daemon (lpd) on AIX systems. An intruder could exploit this
vulnerability to obtain root privileges or cause a denial of service
(DoS). The intruder would need to be listed in the victim's
/etc/hosts.lpd or /etc/hosts.equiv file, however, to exploit this
vulnerability.

VU#466239 - IBM AIX line printer daemon buffer overflow in chk_fhost()

A buffer overflow exists in the chk_fhost() function of the line
printer daemon (lpd) on AIX systems. An intruder could exploit this
vulnerability to obtain root privileges or cause a denial of service
(DoS). The intruder would need control of the DNS server to exploit
this vulnerability.

VU#39001 - line printer daemon allows options to be passed to sendmail

There exists a vulnerability in the line printer daemon that permits
an intruder to send options to sendmail. These options could be used
to specify another configuration file allowing an intruder to gain
root access.

VU#30308 - line printer daemon hostname authentication bypassed with
spoofed DNS

A vulnerability exists in the line printer daemon (lpd) shipped with
the printer package for several systems. The authentication method was
not thorough enough. If a remote user was able to control their own
DNS so that their IP address resolved to the hostname of the print
server, access would be granted when it should not be.

VU#966075 - Hewlett-Packard HP-UX line printer daemon buffer overflow

A buffer overflow exists in HP-UX's line printer daemon (rlpdaemon)
that may allow an intruder to execute arbitrary code with superuser
privilege on the target system. The rlpdaemon is installed by default
and is active even if it is not being used. An intruder does not need
any prior knowledge, or privileges on the target system, in order to
exploit this vulnerability.

II. Impact

All of these vulnerabilities can be exploited remotely. In most cases,
they allow an intruder to execute arbitrary code with the privileges
of the lpd server. In some cases, an intruder must have access to a
machine listed in /etc/hosts.equiv or /etc/hosts.lpd, and in some
cases, an intruder must be able to control a nameserver.

One vulnerability (VU#39001) allows you to specify options to sendmail
that can be used to execute arbitrary commands. Ordinarily, this
vulnerability is only exploitable from machines that are authorized to
use the lpd server. However, in conjunction with another vulnerability
(VU#30308), permitting intruders to gain access to the lpd service,
this vulnerability can be used by intruders not normally authorized to
use the lpd service.

For specific information about the impacts of each of these
vulnerabilities, please consult the CERT Vulnerability Notes Database
(http://www.kb.cert.org/vuls).

III. Solution

Apply a patch from your vendor

Appendix A contains information provided by vendors for this advisory.
As vendors report new information to the CERT/CC, we will update this
section and note the changes in our revision history. If a particular
vendor is not listed below, we have not received their comments.
Please contact your vendor directly.

This table represents the status of each vendor with regard to each
vulnerability. Please be aware that vendors produce multiple products;
if they are listed in this table, not all products may be affected. If
a vendor is not listed in the table below, then their status should be
considered unknown. For specific information about the status of each
of these vulnerabilities, please consult the CERT Vulnerability Notes
Database (http://www.kb.cert.org/vuls).

+ = Affected
- - = Not Affected
? = Unknown

VU# -> |274043 |388183 |722143 |466239 |39001 |30308 |966075
Vendors ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Apple | - | ? | ? | ? | ? | ? | -
BSDI | + | ? | ? | ? | ? | ? | ?
Caldera | - | - | - | - | - | - | -
Cray | ? | - | - | - | - | ? | -
Debian | ? | ? | ? | ? | + | + | ?
Engarde | - | - | - | - | - | - | -
FreeBSD | + | - | - | - | - | - | -
Fujitsu | - | - | - | - | - | - | -
HP | ? | ? | ? | ? | ? | ? | +
IBM | - | + | + | + | - | + | -
Mandrake| ? | ? | ? | ? | + | ? | ?
NetBSD | + | ? | ? | ? | ? | ? | ?
OpenBSD | + | ? | ? | ? | ? | ? | ?
Red Hat | ? | ? | ? | ? | + | + | ?
SCO | + | ? | ? | ? | ? | ? | ?
SGI | + | ? | ? | ? | ? | ? | ?
SuSE | + | ? | ? | ? | ? | ? | ?
Sun | - | - | - | - | + | - | -


Restrict access to the lpd service

As a general practice, we recommend disabling all services that are
not explicitly required. You may wish to disable the line printer
daemon if there is not a patch available from your vendor.

If you cannot disable the service, you can limit your exposure to
these vulnerabilities by using a router or firewall to restrict access
to port 515/TCP (printer). Note that this does not protect you against
attackers from within your network.

Appendix A. - Vendor Information

This appendix contains information provided by vendors for this
advisory. As vendors report new information to the CERT/CC, we will
update this section and note the changes in our revision history. If a
particular vendor is not listed below, we have not received their
comments.

Apple Computer, Inc.

Mac OS X does not have the line printer daemon vulnerability issues
described in these advisories.

Berkeley Software Design, Inc. (BSDI)

Some (older) versions are affected. The current (BSD/OS 4.2) release
is not vulnerable. Systems are only vulnerable to attack from hosts
which are allowed via the /etc/hosts.lpd file (which is empty as
shipped).
BSD/OS 4.1 is the only vulnerable version which is still officially
supported by Wind River Systems. A patch (M410-044) is available in
the normal locations, ftp://ftp.bsdi.com/bsdi/patches or via our web
site at http://www.bsdi.com/support

Compaq

Compaq has not been able to reproduce the problems identified in this
advisory for TRU64 UNIX. We will continue testing and address the LPD
issues if a problem is discovered and provide patches as necessary.

Cray

Cray, Inc. has been unable to prove an lpd vulnerability. However, it
was deemed that a buffer overflow may be possible and so did tighten
up the code. See Cray SPR 721101 for more details.

Debian

http://www.debian.org/security/2000/20000109

FreeBSD, Inc.

ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-01%3A58.lpd.asc

Hewlett-Packard Company

Hewlett-Packard has released
HPSBUX0108-163 Sec. Vulnerability in rlpdaemon
Bulletin and patches available from http://itrc.hp.com
Details to access http://itrc.hp.com are include at the last half of
any HP Bulletin.

IBM Corporation

http://www-1.ibm.com/services/continuity/recover1.nsf/4699c03b46f2d4f68525678c006d45ae/85256a3400529a8685256ac7005cf00a/$FILE/oar391.txt

Mandrake Software

http://www.linux-mandrake.com/en/updates/2000/MDKSA-2000-054.php3

NetBSD

If lpd has been enabled, this issue affects NetBSD versions 1.5.2 and
prior releases, and NetBSD-current prior to August 30, 2001. lpd is
disabled by default in NetBSD installations.

Detailed information will be released subsequent to the publication of
this CERT advisory.

An up-to-date PGP signed copy of the release will be maintained at

ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2001-018.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG and http://www.NetBSD.ORG/Security/.

OpenBSD

http://www.openbsd.org/errata29.html#lpd

RedHat Inc.

http://www.redhat.com/support/errata/RHSA2000002-01.6.0.html

Santa Cruz Operation, Inc. (SCO)

ftp://stage.caldera.com/pub/security/openserver/CSSA-2001-SCO.20/

SGI

ftp://patches.sgi.com/support/free/security/advisories/20011003-01-P

SuSE

http://lists2.suse.com/archive/suse-security-announce/2001-Oct/0000.html
_________________________________________________________________

The CERT Coordination Center thanks Internet Security Systems and IBM
for the information provided in their advisories.
_________________________________________________________________

Feedback on this document can be directed to the author,
Jason A. Rafail
_________________________________________________________________

References
* http://www.kb.cert.org/vuls/id/274043
* http://www.kb.cert.org/vuls/id/388183
* http://www.kb.cert.org/vuls/id/722143
* http://www.kb.cert.org/vuls/id/466239
* http://www.kb.cert.org/vuls/id/39001
* http://www.kb.cert.org/vuls/id/30308
* http://www.kb.cert.org/vuls/id/966075
* http://www.kb.cert.org/vuls
______________________________________________________________________

This document is available from:
http://www.cert.org/advisories/CA-2001-30.html
______________________________________________________________________

CERT/CC Contact Information

Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
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Copyright 2001 Carnegie Mellon University.

Revision History
November 05, 2001: Initial release

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