(EnGarde Issues Fix) Tcpdump l2tp_avp_print() Flaw May Let Remote Users Crash the System With Malformed L2TP Packets
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SecurityTracker Alert ID: 1008762 |
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SecurityTracker URL: http://securitytracker.com/id/1008762
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CVE Reference:
CAN-2003-1029
(Links to External Site)
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Date: Jan 19 2004
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Impact:
Denial of service via network
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Fix Available: Yes Vendor Confirmed: Yes
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Version(s): 3.8.1 and prior versions
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Description:
A vulnerability was reported in tcpdump in the processing of L2TP packets. A remote user may be able to cause tcpdump to crash.
It is reported that there is a flaw in 'print-l2tp.c' that can be triggered by a remote user sending a bad length value in an L2TP packet. The bug reportedly occurs in the l2tp_avp_print() function. A remote user can send a control packet without specifying a length option to cause an infinite loop or potential crash.
Some demonstration exploit examples are provided:
perl -e 'print .\x80\x02...\x00.x6 | nc -u 10.1.1.1 1701
perl -e 'print .\x80\x00...\x00.x6 . .\x01.' | nc -u 10.1.1.1 1701
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Impact:
A remote user can cause tcpdump to enter an infinite loop and potentially crash.
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Solution:
Guardian Digital has released a fix.
Guardian Digital Secure Network subscribers can update automatically via the Guardian Digital WebTool.
The MD5 sums for the updated EnGarde Secure Linux 1.0.1 packages are:
SRPMS/tcpdump-3.6.3-1.0.6.src.rpm
MD5 Sum: 58cf98bad3b20913edb526ef539cfdc0
i386/libpcap-0.6.2-1.0.6.i386.rpm
MD5 Sum: 2dcd5822840fdb9573a898fe631a862f
i386/tcpdump-3.6.3-1.0.6.i386.rpm
MD5 Sum: 61e6669119fc841c3dcec5246b2791c3
i686/libpcap-0.6.2-1.0.6.i686.rpm
MD5 Sum: 44f6af644c763fd67854c3dcedc2c4c1
i686/tcpdump-3.6.3-1.0.6.i686.rpm
MD5 Sum: 127fffc1535823a73fbb0c6961bd4185
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Vendor URL: www.tcpdump.org/ (Links to External Site)
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Cause:
Input validation error, State error
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Underlying OS:
Linux (EnGarde)
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Message History:
This archive entry is a follow-up to the message listed below.
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Source Message Contents
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Date: Mon, 19 Jan 2004 09:47:47 -0500 (EST)
Subject: [ESA-20040119-002] 'tcpdump' multiple vulnerabilities.
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
+------------------------------------------------------------------------+
| Guardian Digital Security Advisory January 19, 2004 |
| http://www.guardiandigital.com ESA-20040119-002 |
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| Packages: libpcap, tcpdump |
| Summary: multiple vulnerabilities. |
+------------------------------------------------------------------------+
EnGarde Secure Linux is an enterprise class Linux platform engineered
to enable corporations to quickly and cost-effectively build a complete
and secure Internet presence while preventing Internet threats.
OVERVIEW
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Several buffer overflows were recently discovered in tcpdump, a program
used for inspecting network traffic. By sending specially constructed
packets across the wire a malicious remote attacker could cause tcpdump
to crash or potentially run arbitrary code as the user under which
tcpdump was being run.
The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the following names to these issues:
CAN-2004-0057 -- The rawprint function in the ISAKMP decoding
routines (print-isakmp.c) for tcpdump 3.8.1 and earlier allows
remote attackers to cause a denial of service (segmentation fault)
via malformed ISAKMP packets that cause invalid "len" or "loc"
values to be used in a loop, a different vulnerability than
CAN-2003-0989.
CAN-2003-0989 -- tcpdump before 3.8.1 allows remote attackers to
cause a denial of service (infinite loop) via certain ISAKMP
packets, a different vulnerability than CAN-2004-0057.
CAN-2003-1029 -- The L2TP protocol parser in tcpdump 3.8.1 and earlier
allows remote attackers to cause a denial of service (infinite loop
and memory consumption) via a packet with invalid data to UDP port
1701, which causes l2tp_avp_print to use a bad length value when
calling print_octets.
Guardian Digital products affected by this issue include:
EnGarde Secure Community v1.0.1
EnGarde Secure Community 2
EnGarde Secure Professional v1.1
EnGarde Secure Professional v1.2
EnGarde Secure Professional v1.5
It is recommended that all users apply this update as soon as possible.
SOLUTION
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Guardian Digital Secure Network subscribers may automatically update
affected systems by accessing their account from within the Guardian
Digital WebTool.
To modify your GDSN account and contact preferences, please go to:
https://www.guardiandigital.com/account/
Below are MD5 sums for the updated EnGarde Secure Linux 1.0.1 packages:
SRPMS/tcpdump-3.6.3-1.0.6.src.rpm
MD5 Sum: 58cf98bad3b20913edb526ef539cfdc0
i386/libpcap-0.6.2-1.0.6.i386.rpm
MD5 Sum: 2dcd5822840fdb9573a898fe631a862f
i386/tcpdump-3.6.3-1.0.6.i386.rpm
MD5 Sum: 61e6669119fc841c3dcec5246b2791c3
i686/libpcap-0.6.2-1.0.6.i686.rpm
MD5 Sum: 44f6af644c763fd67854c3dcedc2c4c1
i686/tcpdump-3.6.3-1.0.6.i686.rpm
MD5 Sum: 127fffc1535823a73fbb0c6961bd4185
REFERENCES
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Guardian Digital's public key:
http://ftp.engardelinux.org/pub/engarde/ENGARDE-GPG-KEY
TCPDUMP's Official Web Site:
http://www.tcpdump.org/
Guardian Digital Advisories:
http://infocenter.guardiandigital.com/advisories/
Security Contact: security@guardiandigital.com
- --------------------------------------------------------------------------
Author: Ryan W. Maple <ryan@guardiandigital.com>
Copyright 2004, Guardian Digital, Inc.
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Copyright(c) 2003 Guardian Digital, Inc. GuardianDigital.com
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