Advisory ID: cisco-sa-20100804-fwsmRevision 1.0
For Public Release 2010 August 4 16:00 UTC (GMT)
Multiple vulnerabilities exist in the Cisco Firewall Services Module
(FWSM) for the Cisco Catalyst 6500 Series Switches and Cisco 7600 Series
Routers that may cause the Cisco FWSM to reload after processing crafted SunRPC
or certain TCP packets. Repeated exploitation could result in a sustained DoS
condition.
Cisco has released free software updates that address these
vulnerabilities. Workarounds are available for the vulnerabilities disclosed in
this advisory.
Note: These vulnerabilities are independent of each other. A device may be
affected by one vulnerability and not affected by another.
This advisory is posted at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100804-fwsm.
Note: The Cisco ASA 5500 Series Adaptive Security Appliances are affected
by the SunRPC inspection vulnerabilities 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-20100804-asa.
The Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500
Series Switches and Cisco 7600 Series Routers is affected by multiple
vulnerabilities. Affected versions of Cisco FWSM Software vary depending on the
specific vulnerability.
SunRPC Inspection Denial of Service Vulnerabilities
Cisco FWSM Software version 3.x and 4.x are affected by these
vulnerabilities only if SunRPC inspection is enabled. SunRPC inspection is
enabled by default.
To check if SunRPC inspection is enabled, use the
show service-policy | include sunrpc command and
confirm that the command returns output, as shown in the following
example:
fwsm#show service-policy | include sunrpc
Inspect: sunrpc , packet 0, drop 0, reset-drop 0
Alternatively, a device that has SunRPC 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 sunrpc
...
!
service-policy global_policy global
Note: The Cisco ASA 5500 Series Adaptive Security Appliances are affected
by the SunRPC inspection vulnerabilities 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-20100804-asa.
TCP Denial of Service Vulnerability
Cisco FWSM Software version 3.x and 4.x are affected by this
vulnerability when configured in multi-mode (with virtual firewalls) and with
any of the following features:
-
ASDM Administrative Access
-
Telnet
-
SSH
To verify if the FWSM is running in multiple mode, use the
show mode command, as shown in the following
example:
FWSM(config)#show mode
Security context mode: multiple
The flash mode is the SAME as the running mode.
The following commands are used to enable the HTTPS server and allow
only hosts on the inside interface with an address in the 192.168.1.0/24
network to create ASDM, SSH or Telnet connections:
asa(config)# http server enable
asa(config)# http 192.168.1.0 255.255.255.0 inside
asa(config)# telnet 192.168.1.0 255.255.255.0 inside
asa(config)# ssh 192.168.1.0 255.255.255.0 inside
Determining Software Versions
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 sub
modules 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 column under "Sw."
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 the
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 these
vulnerabilities.
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.
SunRPC Inspection Denial of Service Vulnerabilities
The Cisco FWSM is affected by three vulnerabilities that may cause the
device to reload during the processing of different crafted SunRPC messages
when SunRPC inspection is enabled.
Note: These vulnerabilities are only triggered by transit traffic; traffic
that is destined to the device does not trigger these vulnerabilities.
These vulnerabilities are documented in Cisco bug IDs
CSCte61710
(
registered customers only)
,
CSCte61622
(
registered customers only)
, and
CSCte61662
(
registered customers only)
; and have been assigned
Common Vulnerabilities and Exposures (CVE) IDs CVE-2010-2818, CVE-2010-2819,
and CVE-2010-2820, respectively.
TCP Denial of Service Vulnerability
You can partition a single FWSM into multiple virtual devices, known as
security contexts. Each context has its own security policy, interfaces, and
administrators. Multiple contexts are similar to multiple standalone devices.
Many features are supported in multiple context mode, which includes routing
tables, firewall features, and management.
Cisco FWSM is affected by a denial of service vulnerability
that could allow an unauthenticated attacker to cause a reload when sending a
series of TCP packets. The Cisco FWSM is only affected by this vulnerability
when is configured in multi-mode (with virtual firewalls) and configured to
accept Telnet, SSH or ASDM connections.
Note: A TCP three-way handshake is needed to exploit this vulnerability.
This vulnerability is only triggered by traffic that is destined to the
affected device; transit traffic does not trigger this vulnerability.
This vulnerability is documented in Cisco bug ID
CSCtg68694
(
registered customers only)
and has been assigned
Common Vulnerabilities and Exposures (CVE) ID CVE-2010-2821.
Cisco has provided scores for the vulnerabilities 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
|
CSCte61710, CSCte61622, CSCte61662 - Passthrough traffic crashes
FWSM with SunRPC inspection
Calculate the environmental score of
CSCte61710,
CSCte61622, CSCte61662
|
|
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
|
|
CSCtg68694 - FWSM may crash with certain TCP sessions in multiple
mode
Calculate the environmental score of
CSCtg68694
|
|
CVSS Base Score - 7.1
|
|
Access Vector
|
Access Complexity
|
Authentication
|
Confidentiality Impact
|
Integrity Impact
|
Availability Impact
|
|
Network
|
Medium
|
None
|
None
|
None
|
Complete
|
|
CVSS Temporal Score - 6.4
|
|
Exploitability
|
Remediation Level
|
Report Confidence
|
|
Functional
|
Official-Fix
|
Confirmed
|
Successful exploitation of all the vulnerabilities described in this
security advisory may cause a reload of the affected appliance. Repeated
exploitation could result in a sustained DoS 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.
|
Vulnerability
|
Major Release
|
First Fixed Release
|
|
SunRPC Inspection Denial of Service Vulnerabilities
(CSCte61710, CSCte61622, and CSCte61662)
|
3.1
|
3.1(17.2)
|
|
3.2
|
3.2(16.1)
|
|
4.0
|
4.0(10.1)
|
|
4.1
|
4.1(1.1)
|
|
TCP Denial of Service Vulnerability (CSCtg68694)
|
3.1
|
Not vulnerable
|
|
3.2
|
3.2(17.2)
|
|
4.0
|
4.0(11.1)
|
|
4.1
|
4.1(1.2)
|
Recommended Releases
The following table lists all recommended releases. These recommended
releases contain the fixes for all vulnerabilities in this advisory. Cisco
recommends upgrading to a release that is equal to or later than these
recommended releases.
|
Major Release
|
Recommended Release
|
|
3.1
|
3.1(18)
|
|
3.2
|
3.2(18)
|
|
4.0
|
4.0(12)
|
|
4.1
|
4.1(2)
|
Software Download
Fixed Cisco FWSM Software can be downloaded from the Software Center on
Cisco.com by visiting
http://www.cisco.com/cisco/web/download/index.html
and navigating to Security > Cisco Catalyst 6500 Series Firewall
Services Module > Firewall Services Module (FWSM) Software.
The SunRPC inspection vulnerabilities can be mitigated by disabling
SunRPC inspection, if it is not required. Administrators can disable SunRPC
inspection by issuing the no inspect sunrpc command
in class configuration sub-mode within policy-map configuration.
The TCP DoS vulnerability can be mitigated by only allowing trusted
hosts to communicate with the FWSM via HTTPs, SSH, or Telnet. For example, the
following commands are used to enable the HTTPS server and allow only hosts on
the inside interface with an address in the 192.168.1.0/24 network to create
ASDM, SSH or Telnet connections:
asa(config)# http server enable
asa(config)# http 192.168.1.0 255.255.255.0 inside
asa(config)# telnet 192.168.1.0 255.255.255.0 inside
asa(config)# ssh 192.168.1.0 255.255.255.0 inside
Additional mitigation techniques that can be deployed on Cisco devices
within the network are available in the Cisco Applied Mitigation Bulletin
companion document for this advisory:
http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20100804-fwsm.
Cisco has released free software updates that address these
vulnerabilities. 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.
These vulnerabilities were found during the troubleshooting
of customer service requests and 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-20100804-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.
|
Revision 1.0
|
2010-August-04
|
Initial public release.
|
|
