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AUSCERT External Security Bulletin Redistribution
ESB-2002.491 -- Cisco Security Advisory
Cisco VPN Client Multiple Vulnerabilities - Second Set
06 September 2002
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: VPN client software prior to v3.6
Vendor: Cisco Systems
Operating System: Windows
Red Hat Linux
Solaris
Mac OS X
Impact: Denial of Service
Access Privileged Data
Access Required: Remote
Ref: ESB-2002.417
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Cisco Security Advisory: Cisco VPN Client Multiple Vulnerabilities - Second Set
Revision 1.0
For Public Release 2002 September 05 UTC 1500
----------------------------------------------------------------------
Contents
Summary
Affected Products
Details
Impact
Software Versions and Fixes
Obtaining Fixed Software
Workarounds
Exploitation and Public Announcements
Status of This Notice
Distribution
Revision History
Cisco Security Procedures
----------------------------------------------------------------------
Summary
Multiple vulnerabilities exist in the Cisco Virtual Private Network (VPN)
Client software. These vulnerabilities are documented as Cisco Bug IDs
CSCdt35749, CSCdt60391, CSCdw87717, CSCdx89416 and CSCdy37058. There are
no workarounds available to mitigate the effects of these vulnerabilities.
This advisory will be posted at
http://www.cisco.com/warp/public/707/vpnclient-multiple2-vuln-pub.shtml.
Affected Products
The VPN Client software program runs on the following platforms.
* Microsoft Windows based PC.
* Red Hat Version 6.2 Linux (Intel), or compatible distribution, using
kernel Version 2.2.12 or later. It does not support kernel Version
2.5.
* Solaris UltraSPARC running a 32-bit or a 64-bit kernel OS Version 2.6
or later.
* Mac OS X Version 10.1.0 or later.
+-------------------------------------------------+
| DDTS Description | Affected Releases |
|-----------------------------+-------------------|
| CSCdt35749 - NETBIOS TCP | * earlier than |
| packet vulnerability | 3.0.5 |
| | * 2.x.x |
|-----------------------------+-------------------|
| CSCdt60391 - Group | * earlier than |
| passwords visible using | 3.5.1C |
| utility program | * 3.1.x |
| | * 3.0.x |
| | * 2.x.x |
|-----------------------------+-------------------|
| CSCdw87717 - Concentrator | * earlier than |
| certificate identity | 3.5.1C |
| vulnerability | * 3.1.x |
| | * 3.0.x |
| | * 2.x.x |
|-----------------------------+-------------------|
| CSCdx89416 - Random number | * earlier than |
| generation improvement | 3.5.2B |
| | * 3.1.x |
| | * 3.0.x |
| | * 2.x.x |
|-----------------------------+-------------------|
| CSCdy37058 - TCP filter | * 3.6(Rel) |
| vulnerability | * earlier than |
| | 3.5.4 |
| | * 3.1.x |
| | * 3.0.x |
| | * 2.x.x |
+-------------------------------------------------+
No other Cisco products are currently known to be affected by these
vulnerabilities.
Details
The VPN Client software program on a remote workstation, communicating
with a Cisco VPN device on an enterprise network or with a service
provider, creates a secure connection over the Internet. Through this
connection you can access a private network as if you were an onsite user.
+-------------------------------------------------+
| DDTS Description | Details |
|--------------------+----------------------------|
| CSCdt35749 - | The VPN Client is |
| NETBIOS TCP packet | vulnerable to NETBIOS TCP |
| vulnerability | packets that have their |
| | source and destination |
| | ports set to 137 (NETBIOS |
| | Name Service). Upon |
| | receiving such a packet, |
| | the VPN Client crashes. |
|--------------------+----------------------------|
| CSCdt60391 - Group | There is a utility program |
| passwords visible | under Windows that can |
| using utility | decipher the group |
| program | password field, which is |
| | shown as a series of |
| | asterisks (***...) on the |
| | authentication property |
| | page of the VPN Client. |
|--------------------+----------------------------|
| CSCdw87717 - | When a VPN Client connects |
| Concentrator | to a VPN Concentrator |
| certificate | using certificates, the |
| identity | VPN Client does not have |
| vulnerability | the ability to verify that |
| | specific certificate DN |
| | fields match in the |
| | certificate received from |
| | the VPN Concentrator. |
|--------------------+----------------------------|
| CSCdx89416 - | The random number |
| Random number | generation process in the |
| generation | VPN Client software has |
| improvement | been significantly |
| | improved to increase the |
| | randomness of the |
| | generated numbers. |
|--------------------+----------------------------|
| CSCdy37058 - TCP | It is possible to get the |
| filter | VPN Client, which is |
| vulnerability | configured for all tunnel |
| | mode (split tunneling |
| | disabled mode), to |
| | acknowledge a TCP packet |
| | via the tunnel-assigned |
| | IP, when the packet is |
| | sent to it from outside |
| | the tunnel. The 3.5.x |
| | releases are protected |
| | against this vulnerability |
| | if the firewall is |
| | configured to be in |
| | "always on" mode. The |
| | 3.6(Rel) release is |
| | vulnerable even when the |
| | firewall is in "always on" |
| | mode. |
+-------------------------------------------------+
These vulnerabilities are documented in the Cisco Bug Toolkit as Bug IDs
CSCdt35749, CSCdt60391, CSCdw87717, CSCdx89416 and CSCdy37058, and can be
viewed after 2002 September 6 at 1500 UTC. To access this tool, you must
be a registered user and you must be logged in.
Impact
+-------------------------------------------------+
| DDTS Description | Impact |
|---------------------+---------------------------|
| CSCdt35749 - | This vulnerability can be |
| NETBIOS TCP packet | exploited to initiate a |
| vulnerability | denial-of-service attack. |
|---------------------+---------------------------|
| CSCdt60391 - Group | Unintended disclosure of |
| passwords visible | the group password. |
| using utility | |
| program | |
|---------------------+---------------------------|
| CSCdw87717 - | This vulnerability could |
| Concentrator | be exploited to initiate |
| certificate | a man-in-the-middle |
| identity | attack. |
| vulnerability | |
|---------------------+---------------------------|
| CSCdx89416 - Random | Improvement in the |
| number generation | randomness of random |
| improvement | numbers generated for use |
| | by the VPN Client. |
|---------------------+---------------------------|
| CSCdy37058 - TCP | This vulnerability could |
| filter | be exploited to leak |
| vulnerability | information about the VPN |
| | Client workstation. |
+-------------------------------------------------+
Software Versions and Fixes
+-------------------------------------------------+
| DDTS Description | Fixed Releases |
|---------------------------+---------------------|
| CSCdt35749 - NETBIOS TCP | * 3.6(Rel) or |
| packet vulnerability | later |
| | * 3.5(Rel) or |
| | later |
| | * 3.1(Rel) or |
| | later |
| | * 3.0.5 or later |
|---------------------------+---------------------|
| CSCdt60391 - Group | * 3.6(Rel) or |
| passwords visible using | later |
| utility program | * 3.5.1C or later |
|---------------------------+---------------------|
| CSCdw87717 - Concentrator | * 3.6(Rel) or |
| certificate identity | later |
| vulnerability | * 3.5.1C or later |
|---------------------------+---------------------|
| CSCdx89416 - Random | * 3.6(Rel) or |
| number generation | later |
| improvement | * 3.5.2B or later |
|---------------------------+---------------------|
| CSCdy37058 - TCP filter | * 3.6.1 or later |
| vulnerability | * 3.5.4 or later |
+-------------------------------------------------+
The procedure to upgrade on the various platforms to the fixed software
version is detailed in the documentation available at
http://www.cisco.com/univercd/cc/td/doc/product/vpn/client/.
Obtaining Fixed Software
Cisco is offering free software upgrades to address these vulnerabilities
for all affected customers. Customers may only install and expect support
for the feature sets they have purchased.
Customers with service contracts should contact their regular update
channels to obtain the free software upgrade identified via this advisory.
For most customers with service contracts, this means that upgrades should
be obtained through the Software Center on Cisco's worldwide website at
http://www.cisco.com/kobayashi/sw-center/vpn/client/ . To access the
software download URL, you must be a registered user and you must be
logged in.
Customers whose Cisco products are provided or maintained through a prior
or existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with obtaining the free software
upgrade(s).
Customers who purchased directly from Cisco but who do not hold a Cisco
service contract, and customers who purchase through third-party vendors
but are unsuccessful at obtaining fixed software through their point of
sale, should obtain fixed software by contacting the Cisco Technical
Assistance Center (TAC) using the contact information listed below. In
these cases, customers are entitled to obtain an upgrade to a later
version of the same release or as indicated by the applicable corrected
software version in Software Versions and Fixes.
Cisco TAC contacts are as follows:
* +1 800 553 2447 (toll free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* e-mail: tac@cisco.com
See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various
languages.
Please have your product serial number available and give the URL of this
advisory as evidence of your entitlement to a free upgrade.
Please do not contact either "psirt@cisco.com" or
"security-alert@cisco.com" for software upgrades.
Workarounds
+-------------------------------------------------+
| DDTS Description | Workaround |
|-------------------------------+-----------------|
| CSCdt35749 - NETBIOS TCP | There is no |
| packet vulnerability | workaround. |
|-------------------------------+-----------------|
| CSCdt60391 - Group passwords | There is no |
| visible using utility program | workaround. |
|-------------------------------+-----------------|
| CSCdw87717 - Concentrator | There is no |
| certificate identity | workaround. |
| vulnerability | |
|-------------------------------+-----------------|
| CSCdx89416 - Random number | Not applicable. |
| generation improvement | |
|-------------------------------+-----------------|
| CSCdy37058 - TCP filter | There is no |
| vulnerability | workaround. |
+-------------------------------------------------+
The Cisco PSIRT recommends that affected users upgrade to a fixed software
version of code.
Exploitation and Public Announcements
The Cisco PSIRT is not aware of any public announcements or malicious use
of the vulnerabilities described in this advisory.
These vulnerabilities were reported to PSIRT by internal development
testing and customers.
Status of This Notice: FINAL
This is a final notice. Although Cisco cannot guarantee the accuracy of
all statements in this advisory, all of the facts have been checked to the
best of our ability. Cisco does not anticipate issuing updated versions of
this advisory unless there is some material change in the facts. Should
there be a significant change in the facts, Cisco may update this
advisory.
A stand-alone copy or paraphrase of the text of this security advisory
that omits the distribution URL in the following section is an
uncontrolled copy, and may lack important information or contain factual
errors.
Distribution
This notice will be posted on Cisco's worldwide website at
http://www.cisco.com/warp/public/707/vpnclient-multiple2-vuln-pub.shtml.
In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the following
e-mail and Usenet news recipients:
* cust-security-announce@cisco.com
* bugtraq@securityfocus.com
* first-teams@first.org (includes CERT/CC)
* cisco@spot.colorado.edu
* comp.dcom.sys.cisco
* firewalls@lists.gnac.com
* Various internal Cisco mailing lists
Future updates of this notice, if any, will be placed on Cisco's worldwide
web server, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
URL given above for any updates.
Revision History
+------------------------------------------------------------+
| Revision 1.0 | 2002-September-05 | Initial public release. |
+------------------------------------------------------------+
Cisco Security Procedures
Complete information on reporting security vulnerabilities in Cisco
products, obtaining assistance with security incidents, and registering to
receive security information from Cisco, is available on Cisco's worldwide
website at http://www.cisco.com/go/psirt. This includes instructions for
press inquiries regarding Cisco security advisories.
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This notice is Copyright 2002 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the text,
provided that redistributed copies are complete and unmodified, and
include all date and version information.
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