Advisory ID: cisco-sa-20110223-fwsmRevision 1.0
For Public Release 2011 February 23 16:00 UTC (GMT)
A vulnerability exists in the Cisco Firewall Services Module (FWSM) for
Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers that may
cause the Cisco FWSM to reload after processing a malformed Skinny Client
Control Protocol (SCCP) message. Devices are affected when SCCP inspection is
enabled.
Cisco has released free software updates that address this
vulnerability.
This advisory is posted at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110223-fwsm.
Note: Cisco ASA 5500 Series Adaptive Security Appliances are affected by
the vulnerability described in this advisory. A separate Cisco Security
Advisory has been published to disclose this and other vulnerabilities that
affect the Cisco ASA 5500 Series Adaptive Security Appliances. The advisory is
available at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110223-asa.
Versions 3.1.x, 3.2.x, 4.0.x, and 4.1.x of Cisco FWSM software are
affected by this vulnerability if SCCP inspection is enabled. SCCP inspection
is enabled by default.
To determine whether SCCP inspection is enabled, issue the
show service-policy | include skinny command and
confirm that the command returns output. Example output follows:
fwsm#show service-policy | include skinny
Inspect: skinny , packet 0, drop 0, reset-drop 0
Alternatively, a device that has SCCP inspection enabled has a
configuration similar to the following:
class-map inspection_default
match default-inspection-traffic
!
policy-map global_policy
class inspection_default
...
inspect skinny
...
!
service-policy global_policy global
Note: The service policy could also be applied to a specific interface.
(Global application is shown in the previous example.)
To determine the version of Cisco FWSM software that is running, issue
the show module command from Cisco IOS Software or
Cisco Catalyst Operating System Software to identify what modules and
submodules are installed on the system.
The following example shows a system with a Cisco FWSM (WS-SVC-FWM-1)
installed in slot 2:
switch>show module
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 16 SFM-capable 16 port 1000mb GBIC WS-X6516-GBIC SAL06334NS9
2 6 Firewall Module WS-SVC-FWM-1 SAD10360485
3 8 Intrusion Detection System WS-SVC-IDSM-2 SAD0932089Z
4 4 SLB Application Processor Complex WS-X6066-SLB-APC SAD093004BD
5 2 Supervisor Engine 720 (Active) WS-SUP720-3B SAL0934888E
Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
1 0009.11e3.ade8 to 0009.11e3.adf7 5.1 6.3(1) 8.5(0.46)RFW Ok
2 0018.ba41.5092 to 0018.ba41.5099 4.0 7.2(1) 3.2(2)10 Ok
3 0014.a90c.9956 to 0014.a90c.995d 5.0 7.2(1) 5.1(6)E1 Ok
4 0014.a90c.66e6 to 0014.a90c.66ed 1.7 4.2(3) Ok
5 0013.c42e.7fe0 to 0013.c42e.7fe3 4.4 8.1(3) 12.2(18)SXF1 Ok
[...]
After locating the correct slot, issue the show module
<slot number> command to identify the software version that
is running, as shown in the following example:
switch>show module 2
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
2 6 Firewall Module WS-SVC-FWM-1 SAD10360485
Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
2 0018.ba41.5092 to 0018.ba41.5099 4.0 7.2(1) 3.2(2)10 Ok
[...]
The preceding example shows that the FWSM is running software version
3.2(2)10 as indicated by the Sw column.
Note: Recent versions of Cisco IOS Software will show the software version
of each module in the output from the show module
command; therefore, executing the show module <slot
number> command is not necessary.
If a Virtual Switching System (VSS) is used to allow two physical Cisco
Catalyst 6500 Series Switches to operate as a single logical virtual switch,
the show module switch all command can display the
software version of all FWSMs that belong to switch 1 and switch 2. The output
from this command will be similar to the output from show module
<slot number> but will include module information for the
modules in each switch in the VSS.
Alternatively, version information can be obtained directly from the
FWSM through the show version command, as shown in
the following example:
FWSM> show version
FWSM Firewall Version 3.2(2)10
[...]
Customers who use the Cisco Adaptive Security Device Manager (ASDM) to
manage their devices can find the version of the software displayed in the
table in the login window or in the upper left corner of the ASDM window. The
version notation is similar to the following example:
FWSM Version: 3.2(2)10
With the exception of Cisco ASA 5500 Series Adaptive Security
Appliances, no other Cisco products are currently known to be affected by this
vulnerability.
The Cisco FWSM is a high-speed, integrated firewall module for Cisco
Catalyst 6500 Series Switches and Cisco 7600 Series Routers. The FWSM offers
firewall services with stateful packet filtering and deep packet
inspection.
The Cisco FWSM is affected by a vulnerability that may cause the device
to reload during the processing of a malformed SCCP message when SCCP
inspection is enabled.
This vulnerability is triggered only by transit traffic; traffic that
is destined to the device does not trigger this vulnerability.
This vulnerability is documented in Cisco bug ID
CSCtl84952
(
registered customers only)
and has been assigned
Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0394.
Cisco has provided scores for the vulnerability in this advisory based
on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this
Security Advisory is done in accordance with CVSS version 2.0.
CVSS is a standards-based scoring method that conveys
vulnerability severity and helps determine urgency and priority of response.
Cisco has provided a base and temporal score. Customers can
then compute environmental scores to assist in determining the impact of the
vulnerability in individual networks.
Cisco has provided an FAQ to answer additional questions
regarding CVSS at:
http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.
Cisco has also provided a CVSS calculator to help compute
the environmental impact for individual networks at:
http://intellishield.cisco.com/security/alertmanager/cvss.
|
CSCtl84952 -- SCCP inspection DoS vulnerability
Calculate the environmental score of
CSCtl84952
|
|
CVSS Base Score - 7.8
|
|
Access Vector
|
Access Complexity
|
Authentication
|
Confidentiality Impact
|
Integrity Impact
|
Availability Impact
|
|
Network
|
Low
|
None
|
None
|
None
|
Complete
|
|
CVSS Temporal Score - 6.4
|
|
Exploitability
|
Remediation Level
|
Report Confidence
|
|
Functional
|
Official-Fix
|
Confirmed
|
Successful exploitation of this vulnerability may cause a reload of the
affected device. Repeated exploitation could result in a sustained denial of
service condition.
When considering software upgrades, also consult
http://www.cisco.com/go/psirt
and any subsequent advisories to determine exposure and a complete upgrade
solution.
In all cases, customers should exercise caution to be
certain the devices to be upgraded contain sufficient memory and that current
hardware and software configurations will continue to be supported properly by
the new release. If the information is not clear, contact the Cisco Technical
Assistance Center (TAC) or your contracted maintenance provider for assistance.
Each row of the following Cisco FWSM software table
describes a major Cisco FWSM software train and the earliest possible release
in that train that contains the fix (the "First Fixed Release") and the
anticipated date of availability (if not currently available) in the First
Fixed Release column. A device that is running a release that is earlier than
the release in a specific column (earlier than the First Fixed Release) is
known to be vulnerable. The release should be upgraded at least to the
indicated release or a later version (later than or equal to the First Fixed
Release label).
|
Major Release
|
First Fixed Release
|
|
3.1
|
3.1(20)
|
|
3.2
|
3.2(20)
|
|
4.0
|
4.0(15)
|
|
4.1
|
4.1(5)
|
Fixed Cisco FWSM software can be downloaded from the Software Center on
Cisco.com by visiting
http://www.cisco.com/cisco/software/navigator.html
(
registered customers only)
and navigating to Products > Security > Firewall > Firewall Integrated
Switch/Router Services > Cisco Catalyst 6500 Series Firewall Services Module
> Firewall Services Module (FWSM) Software.
If SCCP inspection is not required, it can be disabled so the device is
no longer affected by the vulnerability. Administrators can disable SCCP
inspection by issuing the no inspect skinny command
in class configuration submode in the policy map configuration. If SCCP
inspection is required, there are no workarounds.
Cisco has released free software updates that address this
vulnerability. Prior to deploying software, customers should consult their
maintenance provider or check the software for feature set compatibility and
known issues specific to their environment.
Customers may only install and expect support for the
feature sets they have purchased. By installing, downloading, accessing or
otherwise using such software upgrades, customers agree to be bound by the
terms of Cisco's software license terms found at
http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html
, or as otherwise set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml
.
Do not contact psirt@cisco.com or security-alert@cisco.com
for software upgrades.
Customers with contracts should obtain upgraded software through their
regular update channels. For most customers, this means that upgrades should be
obtained through the Software Center on Cisco's worldwide website at
http://www.cisco.com.
Customers whose Cisco products are provided or maintained through prior
or existing agreements with third-party support organizations, such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for guidance and assistance with the appropriate course of
action in regards to this advisory.
The effectiveness of any workaround or fix is dependent on
specific customer situations, such as product mix, network topology, traffic
behavior, and organizational mission. Due to the variety of affected products
and releases, customers should consult with their service provider or support
organization to ensure any applied workaround or fix is the most appropriate
for use in the intended network before it is deployed.
Customers who purchase direct from Cisco but do not hold a Cisco
service contract, and customers who purchase through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale should
acquire upgrades by contacting the Cisco Technical Assistance Center (TAC). 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
Customers should have their product serial number available and be
prepared to give the URL of this notice as evidence of entitlement to a free
upgrade. Free upgrades for non-contract customers must be requested through the
TAC.
Refer to
http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html
for additional TAC contact information, including localized telephone numbers,
and instructions and e-mail addresses for use in various languages.
The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerability described in this advisory.
This vulnerability was found during internal testing.
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This advisory is posted on Cisco's worldwide website at :
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110223-fwsm
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
-
first-bulletins@lists.first.org
-
bugtraq@securityfocus.com
-
vulnwatch@vulnwatch.org
-
cisco@spot.colorado.edu
-
cisco-nsp@puck.nether.net
-
full-disclosure@lists.grok.org.uk
-
comp.dcom.sys.cisco@newsgate.cisco.com
Future updates of this advisory, if any, will be placed on Cisco's
worldwide website, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.
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Revision 1.0
|
2011-February-23
|
Initial public release.
|
|
