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Multiple Vulnerabilities in Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module

Advisory ID: cisco-sa-20111005-asa

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20111005-asa

Revision 1.2

Last Updated  2012 July 14 09:38  UTC (GMT)

For Public Release 2011 October 5 16:00  UTC (GMT)


Summary

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module are affected by multiple vulnerabilities as follows:

  • MSN Instant Messenger (IM) Inspection Denial of Service vulnerability
  • TACACS+ Authentication Bypass vulnerability
  • Four SunRPC Inspection Denial of Service vulnerabilities
  • Internet Locator Service (ILS) Inspection Denial of Service vulnerability

These vulnerabilities are independent; a release that is affected by one vulnerability may not necessarily be affected by the others.

Workarounds for some of the vulnerabilities are provided in this advisory.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20111005-asa.

Note:  The Cisco Firewall Services Module (FWSM) is affected by the TACACS+ authentication bypass vulnerability, SunRPC Inspection denial of service (DoS) vulnerabilities and ILS inspection DoS vulnerability. A separate Cisco Security Advisory has been published to disclose the vulnerabilities that affect the FWSM. This advisory is available at: http://www.cisco.com/warp/public/707/cisco-sa-20110831-fwsm.shtml

Affected Products

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module are affected by multiple vulnerabilities. Affected versions of Cisco ASA Software will vary depending on the specific vulnerability.

Vulnerable Products

For specific version information, refer to the Software Versions and Fixes section of this advisory.

MSN IM Inspection Denial of Service Vulnerability

The MSN IM inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances is affected by a DoS vulnerability.

MSN IM inspection is not enabled by default.

Administrators can enable MSN IM inspection and specify actions when a message violates a parameter, create an IM inspection policy map. You can then apply the inspection policy map when you enable IM inspection, as shown in the following example:

policy-map type inspect im MY-MSN-INSPECT
 parameters
 match protocol msn-im 
  log
!
policy-map global_policy
  class inspection_default
    inspect im MY-MSN-INSPECT

TACACS+ Authentication Bypass Vulnerability

An authentication bypass vulnerability affects the TACACS+ implementation of Cisco ASA 5500 Series Adaptive Security Appliances.

In order to enable TACACS+ for authentication, authorization, or accounting (AAA), you must first create at least one AAA server group per AAA protocol and add one or more servers to each group with the aaa-server command. You identify AAA server groups by name. The following example shows how a AAA server group is configured for TACACS+ authentication:

aaa-server my-tacacs-sever protocol tacacs+     
aaa-server my-tacacs-server (inside) host 203.0.113.11 

SunRPC Inspection Denial of Service Vulnerabilities

Four DoS vulnerabilities affect the SunRPC inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances.

SunRPC inspection is enabled by default.

To check if SunRPC inspection is enabled, issue the show service-policy | include sunrpc command and confirm that output, such as what is displayed in the following example, is returned.

ciscoasa# show service-policy | include sunrpc
      Inspect: sunrpc, packet 0, drop 0, reset-drop 0

The following configuration commands are used to enable SunRPC inspection in the Cisco ASA.

class-map inspection_default
 match default-inspection-traffic
!
policy-map global_policy
 class inspection_default
  ...
  inspect sunrpc 
  ...
!
service-policy global_policy global

ILS Inspection Denial of Service Vulnerability

A DoS vulnerability affects the ILS inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances.

ILS inspection is not enabled by default.

To check if ILS inspection is enabled, issue the show service-policy | include ils command and confirm that output, such as what is displayed in the following example, is returned.

ciscoasa# show service-policy | include ils
      Inspect: ils, packet 0, drop 0, reset-drop 0

The following configuration commands are used to enable ILS inspection in the Cisco ASA.

class-map inspection_default
 match default-inspection-traffic
!
policy-map global_policy
 class inspection_default
  ...
  inspect ils
  ...
!
service-policy global_policy global

How to Determine the Running Software Version

To determine whether a vulnerable version of Cisco ASA Software is running on an appliance, administrators can issue the show version command. The following example shows a Cisco ASA 5500 Series Adaptive Security Appliance that is running software version 8.4(1):

ASA#show version | include Version
Cisco Adaptive Security Appliance Software Version 8.4(1) 
Device Manager Version 6.4(1)

Customers who use Cisco ASDM to manage devices can locate the software version in the table that is displayed in the login window or upper-left corner of the Cisco ASDM window.

Products Confirmed Not Vulnerable

With the exception of the Cisco FWSM, no other Cisco products are currently known to be affected by these vulnerabilities.

Details

Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module are affected by the following vulnerabilities:

MSN IM Inspection Denial of Service Vulnerability

The IM inspect engine lets you apply fine grained controls on the IM application to control the network usage and stop leakage of confidential data, propagation of worms, and other threats to the corporate network.

A DoS vulnerability affects the MSN IM inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances. During successful exploitation, an unauthenticated attacker could cause the affected device to reload and may result in a sustained DoS condition.

Note:  Only transit traffic can trigger this vulnerability; traffic that is destined to the appliance will not trigger the vulnerability. MSN IM inspection is not enabled by default.

This vulnerability is documented in Cisco bug ID  CSCtl67486 ( registered customers only) and has been assigned CVE ID CVE-2011-3304

TACACS+ Authentication Bypass Vulnerability

AAA enables the ASA to determine who the user is (authentication), what the user can do (authorization), and what the user did (accounting). The Cisco ASA supports TACACS+ authentication for VPN users, firewall sessions, and administrative access to the device.

An authentication bypass vulnerability exists in the TACACS+ implementation of the Cisco ASA. Successful exploitation could allow a remote attacker to bypass TACACS+ authentication of VPN users, firewall sessions, or administrative access to the device. The attacker needs to have access to the network between the ASA and the TACACS+ server in order to successfully exploit this vulnerability.

This vulnerability is documented in Cisco bug ID CSCto40365 ( registered customers only) and has been assigned CVE ID CVE-2011-3298.

SunRPC Inspection Denial of Service Vulnerabilities

The Sun RPC inspection engine performs application inspection for the Sun RPC protocol. Sun RPC is used by Network File System (NFS) and Network Information Service (NIS). Sun RPC services can run on any port. When a client attempts to access a Sun RPC service on a server, it must learn the port that service is running on. The client does this by querying the port mapper process, usually rpcbind, on the well-known port of 111.

Four DoS vulnerabilities affect the SunRPC inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances, in which an unauthenticated attacker may cause the affected device to reload.

Note:  Only transit traffic can trigger these vulnerabilities; traffic that is destined to the appliance will not trigger the vulnerabilities. These vulnerabilities can be triggered by using UDP packets, not TCP. SunRPC inspection is enabled by default.

These vulnerabilities are documented in Cisco bug IDs CSCto92380 ( registered customers only) , CSCtq06065 (registered customers only) , CSCtq06062 ( registered customers only) , CSCto92398 ( registered customers only) ; and have been assigned CVE IDs CVE-2011-3299, CVE-2011-3300, CVE-2011-3301 and CVE-2011-3302

ILS Inspection Denial of Service Vulnerability

The ILS inspection engine provides NAT support for Microsoft NetMeeting, SiteServer, and Active Directory products that use LDAP to exchange directory information with an ILS server.

A DoS vulnerability affects the ILS inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances. During successful exploitation, an unauthenticated attacker could cause the affected device to reload and may result in a sustained DoS condition.

Note:  Only transit traffic can trigger this vulnerability; traffic that is destined to the appliance will not trigger the vulnerability. ILS inspection is not enabled by default.

This vulnerability is documented in Cisco bug ID CSCtq57697 ( registered customers only) and has been assigned CVE CVE-2011-3303.

 

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 .

CSCtl67486 - MSN IM Inspection Denial of Service Vulnerability

Calculate the environmental score of CSCtl67486

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


CSCto40365 - TACACS+ Authentication Bypass Vulnerability

Calculate the environmental score of CSCto40365

CVSS Base Score - 7.9

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Adjacent Network

Medium

None

Complete

Complete

Complete

CVSS Temporal Score - 6.5

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed


CSCto92380, CSCtq06065, CSCtq06062, CSCto92398 SunRPC Inspection Denial of Service Vulnerabilities

Calculate the environmental score of CSCto92380, CSCtq06065, CSCtq06062, CSCto92398

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


CSCtq57697 - ILS inspection crash on malformed ILS traffic

Calculate the environmental score of CSCtq57697

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 all the DoS vulnerabilities could cause an affected device to reload. Repeated exploitation could result in a sustained DoS condition.

Successful exploitation of the TACACS+ authentication bypass vulnerability could allow an attacker to bypass authentication of VPN, firewall and/or administrative sessions.

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.

Vulnerability

Major Release

First Fixed Release

MSN Instant Messeger (IM) Inspection Denial of Service Vulnerability (CSCtl67486)

7.0

Not vulnerable

7.1

Not vulnerable

7.2

7.2(5.3)

8.0

8.0(5.25)

8.1

8.1(2.50)

8.2

8.2(5.11)

8.3

8.3(2.23)

8.4

8.4(2)

8.5

8.5(1.1)

TACACS+ Authentication Bypass Vulnerability (CSCto40365)

7.0

7.0(8.13)

7.1

Vulnerable; migrate to 7.2(5.4) or later

7.2

7.2(5.3)

8.0

8.0(5.24)

8.1

8.1(2.50)

8.2

8.2(5)

8.3

8.3(2.18)

8.4

8.4(1.10)

8.5

8.5(1.1)

SunRPC Inspection Denial of Service Vulnerabilities

(CSCto92380, CSCtq06065, CSCtq06062, CSCto92398)

7.0

7.0(8.13)

7.1

Vulnerable; migrate to 7.2(5.4) or later

7.2

7.2(5.4)

8.0

8.0(5.25)

8.1

Vulnerable; migrate to 8.2 or later

8.2

8.2(5.11)

8.3

8.3(2.23)

8.4

8.4(2.6)

8.5

8.5(1.1)

ILS Inspection Denial of Service Vulnerability (CSCtq57697.)

7.0

7.0(8.13)

7.1

Vulnerable; migrate to 7.2(5.4) or later

7.2

7.2(5.4)

8.0

8.0(5.25)

8.1

8.1(2.50)

8.2

8.2(5.6)

8.3

8.3(2.23)

8.4

8.4(2.7)

8.5

8.5(1.1)

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

7.0

7.0(8.13)

7.1

Vulnerable; migrate to 7.2(5.4) or later

7.2

7.2(5.4)

8.0

8.0(5.25)

8.1

Vulnerable; migrate to 8.2 or later

8.2

8.2(5.13)

8.3

8.3(2.25)

8.4

8.4(2.8)

8.5

8.5(1.1)

Cisco ASA Software can be downloaded from the following link: http://www.cisco.com/cisco/software/navigator.html?mdfid=279513386&flowid=22664. Please note that some of these versions are interim versions and they can be found by expanding the "Interim" tab on the download page.

Workarounds

This Cisco Security Advisory describes multiple distinct vulnerabilities. These vulnerabilities and their respective workarounds are independent of each other.

MSN Instant Messeger (IM) Inspection DoS Vulnerability

Administrators can mitigate this vulnerability by disabling MSN IM inspection if it is not required. Administrators can disable MSN IM inspection by issuing the no inspect im command in class configuration sub-mode in the policy map configuration. Disabling MSN IM inspection may cause MSN IM traffic to stop through the security appliance.

TACACS+ Authentication Bypass Vulnerability

There are no workarounds available for this vulnerability other than using a different authentication protocol such as RADIUS, Active Directory, etc.

SunRPC Inspection DoS Vulnerabilities

Administrators can mitigate this vulnerability 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 in the policy map configuration. Disabling SunRPC inspection may cause SunRPC traffic to stop through the security appliance.

ILS Inspection DoS Vulnerability

Administrators can mitigate this vulnerability by disabling ILS inspection if it is not required. Administrators can disable ILS inspection by issuing the no inspect ils command in class configuration sub-mode in the policy map configuration. Disabling ILS inspection may cause ILS traffic to stop through the security appliance.

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 vulnerabilities described in this advisory.

All the DoS vulnerabilities were discovered during internal testing.

The TACACS+ authentication vulnerability was found during the troubleshooting of a customer service request.

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 Security Intelligence Operations at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120711-cts

Additionally, a text version of this advisory is clear signed with the Cisco PSIRT PGP key and circulated among the following e-mail addresses:

  • 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
Future updates of this advisory, if any, will reside on Cisco.com but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.

Revision History

Revision 1.2 2012-July-14 Updated meta-tags for Affected Products.
Revision

1.1

2011-October-05

Updated recommended release table.

Revision

1.0

2011-October-05

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.