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Cisco Security Advisory

Multiple Vulnerabilities in Cisco Secure Access Control Server

Advisory ID: cisco-sa-20070105-csacs

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070105-csacs

Revision 1.0

For Public Release 2007 January 5 16:00  UTC (GMT)


Summary

Certain versions of Cisco Secure Access Control Server (ACS) for Windows and the Cisco Secure ACS Solution Engine (here after both referred to as purely Cisco Secure ACS) are affected by multiple vulnerabilities that cause specific Cisco Secure services to crash. Two of the vulnerabilities may permit arbitrary code execution after exploitation of the specified vulnerability.

Affected Cisco Secure ACS services, and the impact of the vulnerabilities are as follows:

  • Specially Crafted HTTP GET Request Vulnerability:
    Processing a specially crafted HTTP GET request may crash the CSAdmin service. This vulnerability is also susceptible to a stack overflow condition.
  • Specially Crafted RADIUS Accounting-Request Vulnerability:
    Processing a specially crafted RADIUS Accounting-Request packet may crash the CSRadius service. This vulnerability is also susceptible to a stack overflow condition.
  • Specially Crafted RADIUS Access-Request Vulnerabilities:
    Processing a specially crafted RADIUS Access-Request packet may crash the CSRadius service.

We would like to thank CESG's Vulnerability Research Group and National Infrastructure Security Co-ordination Centre (NISCC) for reporting several of these vulnerabilities to Cisco Systems.

We greatly appreciate the opportunity to work with researchers on security vulnerabilities, and welcome the opportunity to review and assist in product reports.

Cisco has released free software updates that address these vulnerabilities. Workarounds that mitigate these vulnerabilities are available. This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070105-csacs.

Affected Products

Any version of Cisco Secure ACS prior to the versions listed in the Fixed Software table below may be susceptible to the listed vulnerabilities.

Vulnerable Products

The following products are vulnerable to one or more of the vulnerabilities, when running software versions prior to 4.1:

  • Cisco Secure Access Control Server for Windows
  • Cisco Secure Access Control Server Solution Engine

To determine if you are running a vulnerable version of Cisco Secure ACS, first log into the Web administrative session for Cisco Secure ACS and on the home page at the bottom section of the screen will be the release information. The following example would be seen when running Cisco Secure ACS software version 4.0(1) Build 27:

CiscoSecure ACS
ACS software version 4.0(1) Build 27:
Copyright information is seen underneath this information.

Products Confirmed Not Vulnerable

  • Cisco Secure ACS for Unix (CSU).
  • Cisco CNS Access Registrar (CAR).
  • Cisco Secure ACS server for Windows version 4.1(X) or later.
  • Cisco Secure ACS server solution Engine version 4.1(X) or later.
No other Cisco products are currently known to be affected by these vulnerabilities.

Details

Cisco Secure ACS is a scalable, high-performance Remote Access Dial-In User Service (RADIUS) and Terminal Access Controller Access Control System Plus (TACACS+) security server.

Multiple vulnerabilities exist in certain versions of the Cisco Secure ACS that may cause the services CSAdmin or CSRadius to crash.

CSAdmin is the service that provides the web server for the ACS web administration interface.

CSRadius is the service that communicates between the CSAuth module (the authentication and authorization service) and the access device that is requesting authentication and authorization services.

Specially Crafted HTTP GET Request Vulnerability

This vulnerability is exploited by processing a specially crafted HTTP GET request. Upon successful exploitation, the CSAdmin service may crash. This vulnerability is also susceptible to a stack based overflow condition which may allow arbitrary code execution if successfully exploited.

If this vulnerability is successfully exploited, the CSAdmin service will require a manual restart of the service. Normal Authentication, Authorization and Accounting (AAA) processing will continue.

While CSAdmin is in the stopped state, users cannot access the Cisco Secure ACS administrative interface from any computer other than the Windows server or appliance on which it is running. With Cisco Secure ACS for Windows you can start or stop CSAdmin from the Windows Control Panel. With Cisco Secure ACS Solution Engine, you can restart the service by using only the appliance serial console.

For further details on starting the CSAdmin service please refer to: http://www.cisco.com/en/US/docs/net_mgmt/cisco_secure_access_control_server_for_windows/4.1/user/A_Arch.html#wp7264

This vulnerability is documented in Cisco Bug ID:

  • CSCsd96293 ( registered customers only) -- Stack based overflow within CSAdmin when processing HTTP GET request

Specially Crafted RADIUS Accounting-Request Vulnerability

This vulnerability is exploited by processing a specially crafted RADIUS Accounting-Request packet. Upon successful exploitation, the CSRadius service may crash and an exception trap error will be generated for the CSRadius service within the Windows Event Viewer System log. This vulnerability is also susceptible to a stack based overflow condition which may allow arbitrary code execution if successfully exploited.

The RADIUS secret key that is shared between the Network Access Server (NAS) and the Cisco Secure ACS server and/or appliance is required to exploit this vulnerability.

This vulnerability is documented in Cisco Bug ID:

  • CSCse18278 ( registered customers only) -- Stack based overflow within CSRadius when processing Accounting-Request. (CVE-2006-4098)

Specially Crafted RADIUS Access-Request Vulnerabilities

Several vulnerabilities exist in Cisco Secure ACS that may cause the CSRadius service to crash when processing a specially crafted RADIUS Access-Request packet. These vulnerabilities will not allow arbitrary code execution after successful exploitation. An exception trap error will be recorded within the CSRadius log file and an error will be seen for the CSRadius service within the Windows Event Viewer System log after successful exploitation.

The RADIUS secret key that is shared between the Network Access Server (NAS) and the Cisco Secure ACS server and/or appliance is not required to exploit these vulnerabilities.

These vulnerabilities are documented in Cisco Bug IDs:

  • CSCse18250 ( registered customers only) -- CSRadius Service crashes when processing a specially crafted Access-Request packet. (CVE-2006-4097)
  • CSCeg04788 ( registered customers only) -- CSRadius Service crashes when processing a specially crafted Access-Request packet.
  • CSCeg04666 ( registered customers only) -- CSRadius Service crashes when processing a specially crafted Access-Request packet.

Vulnerability Scoring Details

Cisco is providing scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS).

Cisco will provide a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco PSIRT will set the bias in all cases to normal. Customers are encouraged to apply the bias parameter when determining the environmental impact of a particular vulnerability.

CVSS is a standards based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

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.

CSCsd96293 ( registered customers only) - Stack based overflow within CSAdmin when processing HTTP GET request.

CVSS Base Score - 10

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

Complete

Complete

Complete

Normal

CVSS Temporal Score - 8.3

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed


CSCse18278 ( registered customers only) - Stack based overflow within CSRadius when processing Accounting-Request.

CVSS Base Score - 6.0

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Required

Complete

Complete

Complete

Normal

CVSS Temporal Score - 5.0

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCse18250 ( registered customers only) - CSRadius Service crashes when processing a specially crafted Access-Request packet.

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

CVSS Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCeg04788 ( registered customers only) - CSRadius Service crashes when processing a specially crafted Access-Request packet.

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

CVSS Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

CSCeg04666 ( registered customers only) - CSRadius Service crashes when processing a specially crafted Access-Request packet.

CVSS Base Score - 3.3

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Impact Bias

Remote

Low

Not Required

None

None

Complete

Normal

CVSS Temporal Score - 2.7

Exploitability

Remediation Level

Report Confidence

Functional

Official Fix

Confirmed

Impact

Specially Crafted HTTP GET Request Vulnerability

Successful exploitation may result in the web administrative interface being unavailable until the CSAdmin Service is restarted from windows control panel. Normal Authentication, Authorization and Accounting (AAA) processing will continue. This vulnerability may allow arbitrary code execution if successfully exploited.

Specially Crafted RADIUS Accounting-Request Vulnerability

Successful exploitation may result in RADIUS Authentication, Authorization and Accounting processing to not be performed until the CSRadius service is restarted. TACACS+ Authentication, Authorization and Accounting (AAA) processing will continue. Repeated exploitation could result in a sustained Denial-of-Service (DoS) condition of the RADIUS AAA services. This vulnerability may allow arbitrary code execution if successfully exploited.

Specially Crafted RADIUS Access-Request Vulnerabilities

Successful exploitation may result in RADIUS Authentication, Authorization and Accounting processing to not be performed as the CSRadius service restarts. TACACS+ Authentication, Authorization and Accounting (AAA) processing will continue. Repeated exploitation could result in a sustained Denial-of-Service (DoS) condition of the RADIUS AAA services.

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 software table (below) describes one of the vulnerabilities described in this document. For each vulnerability the earliest possible Release that contains the fix is listed in the "Availability of First Fixed Release" column. A device running a release that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label) or the appropriate patch applied.

Vulnerability

Major Software Release

Availability of First Fixed Releases *

HTTP Vulnerability

3.1(X)

Vulnerable; Contact TAC

3.2(X)

Vulnerable; Contact TAC

3.3(X)

3.3(4) Build 12.

4.0(X)

Apply patch **.

4.1(X)

Are not vulnerable

Accounting-Request Vulnerability

3.1(X)

Vulnerable; Contact TAC

3.2(X)

Vulnerable; Contact TAC

3.3(X)

3.3(4) Build 12.

4.0(X)

4.0(1) Build 27.

4.1(X)

Are not vulnerable

Access-Request Vulnerabilities

3.1(X)

Vulnerable; Contact TAC

3.2(X)

Vulnerable; Contact TAC

3.3(X)

3.3(3) Build 11.

4.0(X)

4.0(1) Build 27.

4.1(X)

Are not vulnerable

Notes:

* 3.3(4) Build 12 is available by contacting Cisco TAC.

The patch for the HTTP Vulnerability (CSCsd96293 ( registered customers only) ) is available for download from Cisco Secure ACS for Windows: http://www.cisco.com/pcgi-bin/tablebuild.pl/acs-win-3des?psrtdcat20e2

  • ACS-4.0.1-CSAdmin-CSCsd96293.zip: Patch for CSCsd96293
  • ACS-4.0.1-CSAdmin-CSCsd96293.txt: Readme for CSCsd96293

Cisco Secure ACS Solution Engine: http://www.cisco.com/pcgi-bin/tablebuild.pl/acs-soleng-3des?psrtdcat20e2

  • applAcs_4.0.1.44-csadmin-CSCsd96293.zip: Patch for CSCsd96293
  • applAcs_4.0.1.44-CSAdmin-CSCsd96293Readme.txt: Readme for CSCsd96293

Note: Installing the above patch is mutually exclusive with an older patch for CSAdmin, which is also a security related fix - CSCse26719, which is referenced in a previous Cisco Security Response at http://tools.cisco.com/security/center/content/CiscoSecurityResponse/cisco-sr-20060623-acs.

A combined patch, which addresses both the above vulnerabilities, has been posted for ACS-4.0.1 (builds 27 and 49), for windows and ACS Solution Engine (build 44) at the following locations:

Cisco Secure ACS for Windows: http://www.cisco.com/pcgi-bin/tablebuild.pl/acs-win-3des?psrtdcat20e2

  • ACS_4.0.1.27-CSAdmin-SW-CSCsd96293_CSCse26719.txt: Readme File for build 27
  • ACS_4.0.1.27-CSAdmin-SW-CSCsd96293_CSCse26719.zip: Patch File for build 27
  • ACS_4.0.1.49-CSAdmin-SW-CSCsd96293_CSCse26719.txt: Readme File for build 49
  • ACS_4.0.1.49-CSAdmin-SW-CSCsd96293_CSCse26719.zip: Patch File for build 49

Cisco Secure ACS Solution Engine: http://www.cisco.com/pcgi-bin/tablebuild.pl/acs-soleng-3des?psrtdcat20e2

  • applACS_4.0.1.44-CSAdmin-CSCsd96293_CSCse26719.txt: Readme File
  • applACS_4.0.1.44-CSAdmin-CSCsd96293_CSCse26719.zip: Patch File


Workarounds

For Cisco Secure ACS for Windows and Cisco Secure ACS Solution Engine to help mitigate the risks of these vulnerabilities, the following mitigations have been provided.

The effectiveness of any mitigation 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 mitigation or fix is the most appropriate for use in the intended network before it is deployed.

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: http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070105-csacs

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.

Several of these vulnerabilities were reported to Cisco by CESG's Vulnerability Research Group and National Infrastructure Security Co-ordination Centre (NISCC).

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-20070105-csacs

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

2007-January-18

Updates to Software table

Revision 1.0

2007-January-12

Note updates

Revision 1.0

2007-January-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.


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