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CERT Advisory CA-2001-15 Buffer Overflow In Sun Solaris in.lpd Print Daemon
Original release date: June 29, 2001
Last revised: --
Source: CERT/CC
A complete revision history can be found at the end of this file.
Systems Affected
* Solaris 2.6 for SPARC
* Solaris 2.6 x86
* Solaris 7 for SPARC
* Solaris 7 x86
* Solaris 8 for SPARC
* Solaris 8 x86
Overview
A buffer overflow exists in the Solaris BSD-style line printer daemon,
in.lpd, that may allow a remote intruder to execute arbitrary code
with the privileges of the running daemon. This daemon runs with root
privileges on all default installations of vulnerable Solaris systems
listed above.
I. Description
The Solaris in.lpd provides BSD-style services for remote users to
interact with a local printer, listening for remote requests on port
515/tcp (printer). There is an unchecked buffer in the part of the
code responsible for transferring print jobs from one machine to
another. If given too many jobs to work on at once, the printer daemon
may crash or allow arbitrary code to be executed with elevated
privileges on the victim system.
This problem was discovered by the ISS X-Force who have released an
advisory:
http://xforce.iss.net/alerts/advise80.php
The CERT/CC is releasing this advisory before patches are available to
alert a broader community of users to this serious problem. Sun has
suggested several steps system administrators can take in order to
mitigate the risk this vulnerability represents.
Sun recommends several workarounds which may be be applied to
vulnerable systems until production patches are available. These are
enumerated in the "III. Solution" section of this document.
Although the CERT/CC has not received any reports of this
vulnerability being successfully exploited, we do strongly encourage
all affected system adminsitrators to take one or more of the
recommended actions in "III. Solution." Such actions have proven
effective at minimizing the likelihood of being successfully attacked
using vulnerabilities similar to this one.
II. Impact
A remote intruder may be able to execute arbitrary code with the
privileges in the running daemon (typically root). In addition, a
remote intruder may be able to crash vulnerable printer daemons.
III. Solution
Implement a workaround
A number of different workaround strategies have been suggested for
dealing with this problem until patches become available:
* Disable the print service in /etc/inetd.conf if remote print job
handling is unnecessary; see the ISS X-Force advisory for
step-by-step details if needed
* Enable the noexec_user_stack tunable (although this does not
provide 100 percent protection against exploitation of this
vulnerability, it makes the likelihood of a successful exploit
much smaller). Add the following lines to the /etc/system file and
reboot:
set noexec_user_stack = 1
set noexec_user_stack_log = 1
* Block access to network port 515/tcp (printer) at all appropriate
network perimeters
* Deploy tcpwrappers, also available in the tcpd-7.6 package at:
http://www.sun.com/solaris/freeware.html#cd
Apply patches when available
Sun is working on patches; they are not yet available. When ready,
they will be part of the jumbo lp patch set to be released in July
identified by the following ids:
* 106235-xx SunOS 5.6 for sparc
* 106236-xx SunOS 5.6 for x86
* 107115-xx SunOS 5.7 for sparc
* 107116-xx SunOS 5.7 for x86
* 109320-xx SunOS 5.8 for sparc
* 109321-xx SunOS 5.8 for x86
Note that the currently-available jumbo lp patches do not fix this
vulnerability. The in.lpd daemon was not shipped by Sun prior to
Solaris 2.6.
Appendix B. - References
1. http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0353
2. https://www.kb.cert.org/vuls/484011
3. http://xforce.iss.net/alerts/advise80.php
4. http://www.securityfocus.com/bid/2894
5. http://www.sun.com/security
6. http://www.sunfreeware.com/notes.html#tcp_wrappers
7. http://www.sun.com/solaris/freeware.html#cd
8. http://www.sun.com/software/solutions/blueprints/0601/jass_quick_start-v03.html
_________________________________________________________________
The CERT Coordination Center thanks Sun Microsystems for contributing
to the creation of this advisory.
_________________________________________________________________
This document was written by Jeffrey S. Havrilla. If you have feedback
concerning this document, please send email to:
This email address is being protected from spambots. You need JavaScript enabled to view it.
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2001-15.html
______________________________________________________________________
CERT/CC Contact Information
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Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
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Copyright 2001 Carnegie Mellon University.
Revision History
June 29, 2001: Initial release
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