Cisco Security Advisory
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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:
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Customers to access sites that would normally match a billing policy
to be accessed without being charged to the end customer
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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 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110126-csg2.
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Customers to access sites that would normally match a billing policy
to be accessed without being charged to the end customer
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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.
Vulnerable Products
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 ---
Products Confirmed Not Vulnerable
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.
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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.
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There are no workarounds for these vulnerabilities.
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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.
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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.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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