Advisory ID: cisco-sa-20110126-csg2Revision 1.0
For Public Release 2011 January 26 16:00 UTC (GMT)
A service policy bypass vulnerability exists in the Cisco Content
Services Gateway - Second Generation (CSG2), which runs on the Cisco Service
and Application Module for IP (SAMI). Under certain configurations this
vulnerability could allow:
-
Customers to access sites that would normally match a billing policy
to be accessed without being charged to the end customer
-
Customers to access sites that would normally be denied based on
configured restriction policies
Additionally, Cisco IOS Software Release 12.4(24)MD1 on the Cisco CSG2
contains two vulnerabilities that can be exploited by a remote, unauthenticated
attacker to create a denial of service condition that prevents traffic from
passing through the CSG2. These vulnerabilities require only a single content
service to be active on the Cisco CSG2 and can be exploited via crafted TCP
packets. A three-way handshake is not required to exploit either of these
vulnerabilities.
Workarounds that mitigate these vulnerabilities are not
available.
This advisory is posted at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110126-csg2.
The service policy bypass vulnerability affects all versions of the
Cisco IOS Software for the CSG2 prior to the first fixed release, as indicated
in the "Software Versions and Fixes" section of this advisory.
The two denial of service vulnerabilities only affect Cisco IOS
Software Release 12.4(24)MD1 on the Cisco CSG2. No other Cisco IOS Software
releases are affected.
To determine the version of Cisco IOS Software that is running on the
Cisco CSG2, issue the "show module" command from Cisco IOS
Software on the switch on which the Cisco CSG2 module is installed to identify
what modules and sub-modules are installed on the system.
Cisco CSG2 runs on the Cisco Service and Application Module for IP
(SAMI) card, and is identified in the following example in slot 2 via the
WS-SVC-SAMI-BB-K9 identification:
C7600#show module
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 2 Supervisor Engine 720 (Active) WS-SUP720-3BXL JAF1226ARQS
2 1 SAMI Module (csgk9) WS-SVC-SAMI-BB-K9 SAD113906P1
4 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL1127T6XY
Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
1 001e.be6e.a018 to 001e.be6e.a01b 5.6 8.5(2) 12.2(33)SRC5 Ok
2 001d.45f8.f3dc to 001d.45f8.f3e3 2.1 8.7(0.22)FW1 12.4(2010040 Ok
4 001c.587a.ef20 to 001c.587a.ef4f 2.6 12.2(14r)S5 12.2(33)SRC5 Ok
Mod Sub-Module Model Serial Hw Status
---- --------------------------- ------------------ ----------- ------- -------
1 Policy Feature Card 3 WS-F6K-PFC3BXL JAF1226BNQM 1.8 Ok
1 MSFC3 Daughterboard WS-SUP720 JAF1226BNMC 3.1 Ok
2 SAMI Daughterboard 1 SAMI-DC-BB SAD114400L9 1.1 Other
2 SAMI Daughterboard 2 SAMI-DC-BB SAD114207FU 1.1 Other
4 Centralized Forwarding Card WS-F6700-CFC SAL1029VGFK 2.0 Ok
Mod Online Diag Status
---- -------------------
1 Pass
2 Pass
4 Pass
C7600#
After locating the correct slot, issue the "session slot
<module number> processor <3-9>" command to open a console
connection to the respective Cisco CSG2. Once connected to the Cisco CSG2,
perform the "show version" command:
The following example shows that the Cisco CSG2 is running software
Release 12.4(24)MD1:
CSG2#show version
Cisco IOS Software, SAMI Software (SAMI-CSGK9-M), Version 12.4(24)MD1, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Wed 07-Apr-10 09:50 by prod_rel_team
--- output truncated ---
The Cisco Content Services Gateway - 1st Generation (CSG) is not
affected by these vulnerabilities.
No other Cisco products are currently known to be affected by these
vulnerabilities.
The Cisco Content Services Gateway - Second Generation (CSG2) provides
intelligent network capabilities such as flexible policy management and billing
based on deep-packet inspection, as well as subscriber and application
awareness capabilities that enable mobile operators to quickly and easily offer
value-added, differentiated services over their mobile data networks.
The service policy bypass vulnerability affects configurations that
allow end users to first access non-accounted or billed sites. After a user
accesses a non-accounted site, it is possible to access other sites that are
defined by a billing service policy or to access sites that may be blocked by
other policies by sending specially crafted HTTP packets. This vulnerability
only affects HTTP content traffic. HTTPS and other traffic types are not
affected.
Both denial of service vulnerabilities require only a single content
service to be active on the Cisco CSG2 and can be exploited via crafted TCP
packets. A three-way handshake is not required to exploit either of these
vulnerabilities. The vulnerabilities are triggered by TCP traffic that transits
the Cisco CSG2.
The service policy bypass vulnerability is documented in Cisco Bug ID
CSCtk35917
(
registered customers only)
and has been assigned
CVE ID CVE-2011-0348.
The denial of service bugs are documented in Cisco Bug ID
CSCth17178
(
registered customers only)
and Cisco Bug ID
CSCth41891
(
registered customers only)
and have been assigned
CVE IDs CVE-2011-0349 and CVE-2011-0350 respectively.
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 .
|
CSCtk35917: Service Policy Bypass Vulnerability
Calculate the environmental score of
CSCtk35917
|
|
CVSS Base Score - 6.4
|
|
Access Vector
|
Access Complexity
|
Authentication
|
Confidentiality Impact
|
Integrity Impact
|
Availability Impact
|
|
Network
|
Low
|
None
|
Partial
|
Partial
|
None
|
|
CVSS Temporal Score - 5.3
|
|
Exploitability
|
Remediation Level
|
Report Confidence
|
|
Functional
|
Official-Fix
|
Confirmed
|
|
CSCth41891/CSCth17178: Crafted TCP packet causes CSG2 to
restart
Calculate the environmental score of
CSCth41891/CSCth17178
|
|
CVSS Base Score - 7.8
|
|
Access Vector
|
Access Complexity
|
Authentication
|
Confidentiality Impact
|
Integrity Impact
|
Availability Impact
|
| |
Low
|
None
|
None
|
None
|
Complete
|
|
CVSS Temporal Score - 6.4
|
|
Exploitability
|
Remediation Level
|
Report Confidence
|
|
Functional
|
Official-Fix
|
Confirmed
|
Successful exploitation of the service policy bypass can allow
customers to obtain access to sites that would normally be accounted and billed
according to the billing policy without the billing policy being engaged.
Additionally, customers could gain access to URLs that are configured in the
Cisco CSG2 to be explicitly denied.
Successful exploitation of either denial of service vulnerability could
result in the Cisco CSG2 reloading or potentially hanging. Due to Cisco Bug ID
CSCtg50821
(
registered customers only)
, the Cisco CSG2 may not
automatically recover and may require a manual reload of the SAMI card by
issuing the "hw-module module <x> reset" CLI command
from the switch.
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 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
|
|
Affected 12.x-Based Releases
|
First Fixed Release
|
|
12.0 - 12.3
|
12.0 through 12.3 based releases are not affected
|
|
Affected 12.4-Based Releases
|
First Fixed Release
|
|
DoS Vulnerabilities
|
Service Policy Bypass Vulnerability
|
|
12.4MD
|
All 12.4(11)MD releases are not affected.
All 12.4(15)MD releases are not affected.
All 12.4(22)MD releases are not affected.
Releases prior to 12.4(24)MD1 are not affected.
First fixed in 12.4(24)MD2
|
All 12.4(11)MD releases are affected. Migrate to a fixed
release.
All 12.4(15)MD releases are affected. Migrate to a fixed
release.
All 12.4(22)MD releases are affected. Migrate to a fixed
release.
All 12.4(24)MD releases prior to 12.4(24)MD3 are affected.
First fixed in 12.4(24)MD3
|
|
12.4MDA
|
No releases affected.
|
All 12.4(22)MDA releases prior to 12.4(22)MDA5 are affected.
First fixed in 12.4(22)MDA5
All 12.4(24)MDA releases prior to 12.4(24)MDA3 are affected.
First fixed in 12.4(24)MDA3
|
|
Affected 15.X-Based Releases
|
First Fixed Release
|
|
15.0 - 15.1
|
15.0 through 15.1 based releases are not affected
|
Cisco IOS Software for the CSG2 is located on Cisco Software Download
center at the following location: Cisco Interfaces and Modules --> Cisco
Services Modules --> Cisco Service Application Module for IP.
There are no workarounds for these vulnerabilities.
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 aware of public announcements of the service billing
bypass vulnerability on some external blog sites. However the Cisco PSIRT is
not aware of any malicious use of the vulnerabilities described in this
advisory.
These vulnerabilities were found by both internal testing
and when handling customer support calls.
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-20110126-csg2
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
|
2011-January-26
|
Initial public release.
|
|
