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Cisco Security Advisory

Cisco Content Services Gateway Denial of Service Vulnerability

Advisory ID: cisco-sa-20110706-csg

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110706-csg

Revision 1.0

For Public Release 2011 July 6 16:00  UTC (GMT)


Summary

A denial of service (DoS) vulnerability exists in the Cisco Content Services Gateway - Second Generation, that runs on the Cisco Service and Application Module for IP (SAMI). An unauthenticated, remote attacker could exploit this vulnerability by sending a series of crafted ICMP packets to an affected device. Exploitation could cause the device to reload.

There are no workarounds available to mitigate exploitation of this vulnerability other than blocking ICMP traffic destined to the affected device.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110706-csg.

Affected Products

Vulnerable Products

All versions of the Cisco IOS Software for the Content Services Gateway: Second Generation prior to the first fixed release are affected, as indicated in the "Software Versions and Fixes" section of this advisory.

Determining Cisco CSG Software Versions

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 Content Services Gateway: Second Generation 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 Content Services Gateway: Second Generation. For example: session slot 2 processor 3. The number 3 is the control processor (CP) number for the CSG2. Always session into CP 3 when configuring or monitoring the Cisco Content Services Gateway: Second Generation. Once connected to the Cisco Content Services Gateway: Second Generation, perform the "show version" command:

The following example shows that the Cisco Content Services Gateway: Second Generation 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

Content Services Gateway: First Generation is not affected by this vulnerability.

Note: Other SAMI-based applications are not affected. The Cisco Gateway GPRS Support Node (GGSN), the Cisco Mobile Wireless Home Agent (HA), the Cisco Wireless Security Gateway (WSG), the Cisco Broadband Wireless Gateway and Cisco IP Transfer Point (ITP), and the Cisco Long Term Evolution (LTE) Gateway are not affected.

The Cisco 7600 Series Router is not affected by this vulnerability, only the Cisco CSG (2nd generation) module is affected.

No other Cisco products are currently known to be affected by this vulnerability.

Details

The Cisco Content Services Gateway: Second Generation 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.

A DoS vulnerability exists in the Cisco Content Services Gateway: Second Generation could allow an unauthenticated attacker to cause a device reload by sending crafted ICMP messages to the affected device.

Note: The Cisco Gateway GPRS Support Node (GGSN), the Cisco Mobile Wireless Home Agent (HA), the Cisco Wireless Security Gateway (WSG), the Cisco Broadband Wireless Gateway and Cisco IP Transfer Point (ITP), and the Cisco Long Term Evolution (LTE) Gateway are not affected.

This vulnerability is documented in Cisco bug ID CSCtl79577 ( registered customers only) and has been assigned CVE ID CVE-2011-2064.

Vulnerability Scoring Details

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 .


CSCtl79577 - Crafted ICMP Packets may cause CSG2 to reload

Calculate the environmental score of CSCtl79577

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

Impact

Successful exploitation of this vulnerability could cause an affected device to reload. Repeated exploitation could result in a sustained DoS condition.

The Cisco 7600 Series Router is not affected by this vulnerability, only the Cisco Content Services Gateway: Second Generation module is affected.

Software Versions and Fixes

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 vulnerability 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

12.4MD

Not vulnerable

12.4MDA

All 12.4MDA releases prior to 12.4(24)MDA5 are affected. First fixed in 12.4(24)MDA5

12.4MDB

Not vulnerable

Affected 15.X-Based Releases

First Fixed Release

15.0 - 15.1

15.0 through 15.1 based releases are not affected


Workarounds

There are no available workarounds to mitigate this vulnerability other than applying infrastructure access control lists (iACLs) on the Cisco 7600 router to block ICMP traffic destined to the IP address of the Cisco CSG. Administrators can construct an iACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. An iACL workaround cannot provide complete protection against these vulnerabilities when the attack originates from a trusted source address.

The iACL policy denies unauthorized ICMP packet types, including echo request, echo-reply, host-unreachable, traceroute, packet-too-big, time-exceeded, and unreachable, that are sent to affected devices. In the following example, 192.168.60.0/24 is the IP address space that is used by the affected devices, and the host at 192.168.100.1 is considered a trusted source that requires access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic. Whenever possible, infrastructure address space should be distinct from the address space used for user and services segments. Using this addressing methodology will assist with the construction and deployment of iACLs.

Additional information about iACLs is in Protecting Your Core: Infrastructure Protection Access Control Lists.

ip access-list extended Infrastructure-ACL-Policy
 
 !
  !-- Include explicit permit statements for trusted sources 
  !-- that require access on the vulnerable protocol  
  !

  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 echo
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 echo-reply
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 host-unreachable
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 traceroute
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 packet-too-big
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 time-exceeded
  permit icmp host 192.168.100.1 192.168.60.0 0.0.0.255 unreachable
  
  !
  !-- The following vulnerability-specific access control entries
  !-- (ACEs) can aid in identification of attacks
  !

  deny icmp any 192.168.60.0 0.0.0.255 echo
  deny icmp any 192.168.60.0 0.0.0.255 echo-reply
  deny icmp any 192.168.60.0 0.0.0.255 host-unreachable
  deny icmp any 192.168.60.0 0.0.0.255 traceroute
  deny icmp any 192.168.60.0 0.0.0.255 packet-too-big
  deny icmp any 192.168.60.0 0.0.0.255 time-exceeded
  deny icmp any 192.168.60.0 0.0.0.255 unreachable

  !
  !-- Explicit deny ACE for traffic sent to addresses configured within
  !-- the infrastructure address space
  !

  deny ip any 192.168.60.0 0.0.0.255
  
!
  !-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
  !-- with existing security policies and configurations
  !
!-- Apply iACL to interfaces in the ingress direction
!

interface GigabitEthernet0/0
 ip access-group Infrastructure-ACL-Policy in

Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory, which is available at the following link: http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20110706-csg

Obtaining Fixed Software

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 Service Contracts

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 Using Third-Party Support Organizations

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 Without Service Contracts

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.

Exploitation and Public Announcements

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.

Status of This Notice: Final

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.


Distribution

This advisory is posted on Cisco's worldwide website at:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110706-csg

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-teams@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 History

Revision 1.0

2011-July-06

Initial public release.

Cisco Security Procedures

Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.


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