Advisory ID: cisco-sa-20090923-ios-fwRevision 1.1
For Public Release 2009 September 23 16:00 UTC (GMT)
Cisco IOS® devices that are configured with
Cisco IOS Zone-Based Policy Firewall Session Initiation Protocol (SIP)
inspection are vulnerable to denial of service (DoS) attacks when processing a
specific SIP transit packet. Exploitation of the vulnerability could result in
a reload of the affected device.
Cisco has released free software updates that address this
vulnerability.
Workarounds that mitigate this vulnerability are available.
This advisory is posted at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20090923-ios-fw
Note: The September 23, 2009, Cisco IOS Security Advisory bundled
publication includes eleven Security Advisories. Ten of the advisories address
vulnerabilities in Cisco IOS Software, and one advisory addresses a
vulnerability in Cisco Unified Communications Manager. Each advisory lists the
releases that correct the vulnerability or vulnerabilities detailed in the
advisory.
Individual publication links are in "Cisco Event Response:
Semiannual Cisco IOS Software Advisory Bundled Publication" at the following
link:
http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep09.html
This vulnerability affects a limited number of Cisco IOS Software
releases. Consult the "Software Versions and Fixes" section of this advisory
for the details of affected releases.
Only devices that are configured with Cisco IOS Zone-Based Policy
Firewall SIP inspection (UDP port 5060, TCP ports 5060, and 5061) are
vulnerable. Cisco IOS devices that are configured with legacy Cisco IOS
Firewall Support for SIP (context-based access control (CBAC)) are not
vulnerable.
To determine the Cisco IOS Software release that is running on a Cisco
product, administrators can log in to the device and issue the show
version command to display the system banner. The system banner
confirms that the device is running Cisco IOS Software by displaying text
similar to "Cisco Internetwork Operating System Software" or "Cisco IOS
Software." The image name displays in parentheses, followed by "Version" and
the Cisco IOS Software release name. Other Cisco devices do not have the
show version command or may provide different output.
The following example identifies a Cisco product that is
running Cisco IOS Software Release 12.3(26) with an installed image name of
C2500-IS-L:
Router#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright ©) 1986-2008 by cisco Systems, Inc.
Compiled Mon 17-Mar-08 14:39 by dchih
<output truncated>
The following example identifies a Cisco product that is running Cisco
IOS Software Release 12.4(20)T with an installed image name of
C1841-ADVENTERPRISEK9-M:
Router#show version
Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright ©) 1986-2008 by Cisco Systems, Inc.
Compiled Thu 10-Jul-08 20:25 by prod_rel_team
<output truncated>
Additional information about Cisco IOS Software release naming
conventions is available in "White Paper: Cisco IOS Reference Guide" at the
following link: http://www.cisco.com/warp/public/620/1.html
The device is vulnerable if the configuration has either a layer 3 or
layer 7 SIP application-specific policy configured, and these policies are
applied to any firewall zone. To determine whether the device is running a
vulnerable configuration, log in to the device and issue the command line
interface (CLI) command show policy-map type inspect zone-pair |
include atch: access|protocol sip. If the output contains
"Match: protocol sip", the device is vulnerable. If the output
contains Match: access-group number
, then
the device is only vulnerable if, the referenced access list
permits the SIP protocol (UDP port 5060, or TCP ports 5060 and 5061). The
following example shows a vulnerable device configured with Cisco IOS
Zone-Based Policy Firewall SIP inspection:
Router#show policy-map type inspect zone-pair | include atch: access|protocol sip
Match: protocol sip
Router#
The following example shows a vulnerable device configured with SIP
inspection by way of an applied access list:
Router#show policy-map type inspect zone-pair | include atch: access|protocol sip
Match: access-group 102
Router#
Router#show access-list 102
Extended IP access list 102
10 permit udp any any eq 5060
20 permit tcp any any eq 5060
30 permit tcp any any eq 5061
Router#
A device that is not configured for SIP inspection or does not support
this configuration will return either a blank line or an error message. The
following is an example of a device that supports Cisco IOS Firewall but does
not have SIP inspection enabled:
Router#show policy-map type inspect zone-pair | include atch: access|protocol sip
Router#
No other Cisco products are currently known to be affected by this
vulnerability. Products confirmed not vulnerable include:
-
Cisco PIX 500 Series Firewall
-
Cisco ASA 5500 Series Adaptive Security Appliance
-
Firewall Services Module (FWSM) for Catalyst 6500 Series Switches and
7600 Series Routers
-
Virtual Firewall (VFW) application on the multiservice blade (MSB) on
the Cisco XR 12000 Series Router
-
Cisco ACE Application Control Engine Module
-
Cisco IOS devices NOT configured with Cisco IOS Zone-Based Policy
Firewall SIP inspection.
-
Cisco IOS devices configured with legacy Cisco IOS Firewall Support
for SIP (CBAC)
-
Cisco IOS XE Software
-
Cisco IOS XR Software
Firewalls are networking devices that control access to the network
assets of an organization. Firewalls are often positioned at the entrance
points into networks. Cisco IOS software provides a set of security features
that enable you to configure a simple or elaborate firewall policy, according
to your particular requirements.
SIP inspection in the Cisco IOS Firewall provides basic SIP inspect
functionality (SIP packet inspection and pinhole opening) as well as protocol
conformance and application security.
Cisco IOS Software that is configured with Cisco IOS Zone-Based Policy
Firewall SIP inspection are vulnerable to a DoS attack when processing a
specific SIP transit packet. Exploitation of this vulnerability will result in
a reload of the affected device.
Cisco IOS Zone-Based Policy Firewall SIP inspection was first
introduced in Cisco IOS Software versions 12.4(15)XZ and 12.4(20)T.
Cisco IOS Firewall CBAC support for SIP inspection by way of the
ip inspect name [inspection_name] sip is not vulnerable.
Additional information regarding Cisco IOS Firewall CBAC support for SIP
inspection is available in the document "Firewall Support for SIP" at the
following link:
http://www.cisco.com/en/US/docs/ios/sec_data_plane/configuration/guide/sec_fwall_sip_supp.html
Additional information regarding Cisco IOS Zone-Based Policy Firewall
SIP inspection is available in the document "Cisco IOS Firewall: SIP
Enhancements: ALG and AIC" at the following link:
http://www.cisco.com/en/US/docs/ios/security/configuration/guide/sec_sip_alg_aic.html
This vulnerability is documented in the following Cisco Bug ID:
CSCsr18691
(
registered customers only)
and has been assigned
the Common Vulnerabilities and Exposures (CVE) identifier CVE-2009-2867.
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 .
|
CSCsr18691: Cisco IOS Software Zone-Based Policy Firewall
Vulnerability
Calculate the environmental score of
CSCsr18691
|
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CVSS Base Score - 7.8
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Access Vector
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Access Complexity
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Authentication
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Confidentiality Impact
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Integrity Impact
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Availability Impact
|
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Network
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Low
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None
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None
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None
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Complete
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CVSS Temporal Score - 6.4
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Exploitability
|
Remediation Level
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Report Confidence
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Functional
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Official-Fix
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Confirmed
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Successful exploitation of the vulnerability may result in a reload of
the affected device. Repeated exploit attempts may result in a sustained DoS
attack.
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 Cisco IOS software table (below) names a
Cisco IOS release train. If a given release train is vulnerable, then the
earliest possible releases that contain the fix (along with the anticipated
date of availability for each, if applicable) are listed in the "First Fixed
Release" column of the table. The "Recommended Release" column indicates the
releases which have fixes for all the published vulnerabilities at the time of
this Advisory. A device running a release in the given train that is earlier
than the release in a specific column (less than the First Fixed Release) is
known to be vulnerable. Cisco recommends upgrading to a release equal to or
later than the release in the "Recommended Releases" column of the table.
|
Major Release
|
Availability of Repaired Releases
|
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Affected 12.0-Based Releases
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First Fixed Release
|
Recommended Release
|
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There are no affected 12.0 based releases
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Affected 12.1-Based Releases
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First Fixed Release
|
Recommended Release
|
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There are no affected 12.1 based releases
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Affected 12.2-Based Releases
|
First Fixed Release
|
Recommended Release
|
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There are no affected 12.2 based releases
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Affected 12.3-Based Releases
|
First Fixed Release
|
Recommended Release
|
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There are no affected 12.3 based releases
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Affected 12.4-Based Releases
|
First Fixed Release
|
Recommended Release
|
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12.4
|
Not Vulnerable
|
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12.4GC
|
Not Vulnerable
|
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12.4JA
|
Not Vulnerable
|
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12.4JDA
|
Not Vulnerable
|
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12.4JDC
|
Not Vulnerable
|
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12.4JDD
|
Not Vulnerable
|
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12.4JK
|
Not Vulnerable
|
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12.4JL
|
Not Vulnerable
|
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12.4JMA
|
Not Vulnerable
|
|
|
12.4JMB
|
Not Vulnerable
|
|
|
12.4JX
|
Not Vulnerable
|
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12.4MD
|
Not Vulnerable
|
|
|
12.4MDA
|
Not Vulnerable
|
|
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12.4MR
|
Not Vulnerable
|
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12.4SW
|
Not Vulnerable
|
|
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12.4T
|
Releases prior to 12.4(20)T are not vulnerable;
12.4(20)T2
12.4(22)T1
12.4(24)T
|
12.4(20)T4
12.4(22)T3
12.4(24)T2; Available on 23-OCT-2009
|
|
12.4XA
|
Not Vulnerable
|
|
|
12.4XB
|
Not Vulnerable
|
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12.4XC
|
Not Vulnerable
|
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12.4XD
|
Not Vulnerable
|
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12.4XE
|
Not Vulnerable
|
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12.4XF
|
Not Vulnerable
|
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12.4XG
|
Not Vulnerable
|
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12.4XJ
|
Not Vulnerable
|
|
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12.4XK
|
Not Vulnerable
|
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12.4XL
|
Not Vulnerable
|
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12.4XM
|
Not Vulnerable
|
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12.4XN
|
Not Vulnerable
|
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12.4XP
|
Not Vulnerable
|
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12.4XQ
|
Not Vulnerable
|
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12.4XR
|
Not Vulnerable
|
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12.4XT
|
Not Vulnerable
|
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12.4XV
|
Not Vulnerable
|
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12.4XW
|
Not Vulnerable
|
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12.4XY
|
Not Vulnerable
|
|
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12.4XZ
|
Vulnerable; first fixed in 12.4T
|
12.4(20)T4
12.4(22)T3
12.4(24)T2; Available on 23-OCT-2009
|
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12.4YA
|
Vulnerable; first fixed in 12.4T
|
12.4(22)T3
12.4(24)T2; Available on 23-OCT-2009
|
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12.4YB
|
12.4(22)YB4
|
12.4(22)YB4
12.4(22)YB5; Available on 19-OCT-2009
|
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12.4YD
|
Not Vulnerable
|
|
|
12.4YE
|
Not Vulnerable
|
|
The only workaround for this vulnerability is to disable Cisco IOS
zone-based policy firewall SIP inspection in the affected device's
configuration. Disabling SIP inspection will allow the rest of the firewall
features to continue to function until a software upgrade can be implemented.
All other firewall features will continue to perform normally. Disabling SIP
Inspection will vary depending on the implementation of the SIP inspection
firewall.
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 discovered by Cisco 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-20090923-ios-fw
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
|
2009-September-23
|
Initial public release
|
|
