Summary

• Cisco Secure Access Control Server for Windows (ACS Windows) and Cisco Secure Access Control Server Solution Engine (ACS Solution Engine) provide authentication, authorization, and accounting (AAA) services to network devices such as a network access server, Cisco PIX and a router. This advisory documents multiple Denial of Service (DoS) and authentication related vulnerabilities for the ACS Windows and the ACS Solution Engine servers.

  The vulnerabilities are documented as these Cisco bug IDs:

  • CSCeb60017 ( registered customers only)
    
  • CSCec66913 ( registered customers only)
    
  • CSCec90317 ( registered customers only)
    
  • CSCed81716 ( registered customers only)
    
  • CSCef05950 ( registered customers only)
    

  This advisory will be posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040825-acs.

Affected Products

• This section provides details on affected products.

  Vulnerable Products

  These products are vulnerable:

  • Versions 3.2(3) and earlier are vulnerable to CSCef05950 ( registered customers only) and CSCed81716 ( registered customers only) .
    
  • Version 3.2(2) build 15 is vulnerable to CSCeb60017 ( registered customers only) .
    
  • Version 3.2 is vulnerable to CSCec90317 ( registered customers only) and CSCec66913 ( registered customers only) .
    

  CSCed81716 is only applicable to the ACS Solution Engine.

  Successfully authenticate to your ACS box to determine your software revision. After you perform the authentication, the first screen displays the current ACS version in this format—CiscoSecure ACS Release 3.2(3) Build 11.

  ACS versions may also be displayed as 003.002(003.011), where "011" is the build number referenced on the ACS graphical user interface (GUI).

  Products Confirmed Not Vulnerable

  Cisco Secure ACS for UNIX is not affected by these vulnerabilities. No other Cisco products are currently known to be affected by these vulnerabilities.

Details

• The Cisco Secure ACS products provide a centralized identity networking solution and simplified user management experience across all Cisco devices and security management applications. The products help to ensure enforcement of assigned policies—they allow network administrators to control who can log into the network, per user privileges in the network, security auditing and billing information, and command level access controls.

  • CSCeb60017 ( registered customers only) and CSCec66913 ( registered customers only) -- Cisco Secure ACS provides a Web-based management interface, termed CSAdmin, which listens on TCP port 2002. When flooded with TCP connections the ACS Windows and ACS Solution Engine stops responding to any new TCP connections destined for port 2002. Additionally, services on the ACS that process authentication related requests may become unstable and stop responding, which hampers the ability for ACS to process any authentication related requests. A reboot of the device is required to restore these services.
    
  • CSCec90317 ( registered customers only) -- Cisco Secure ACS, when configured for Light Extensible Authentication Protocol (LEAP) RADIUS Proxy, forwards LEAP authentication requests to a secondary RADIUS server. The ACS device with LEAP RADIUS proxy configured may crash when LEAP authentication requests are being processed. A reboot is required to bring the device back to an operational state.
    
  • CSCed81716 ( registered customers only) -- Cisco Secure ACS can communicate with external databases and authenticate users against those databases. One of the external databases that ACS supports is Novell Directory Services (NDS). If an anonymous bind in NDS is allowed, and if the ACS Solution Engine is authenticating NDS users with NDS as the external database and not Generic LDAP, then users are able to authenticate with blank passwords against that NDS database. However, wrong passwords and incorrect usernames are properly rejected.
    
  • CSCef05950 ( registered customers only) -- Once a user successfully authenticates to the ACS GUI on TCP port 2002, a separate TCP connection is created between the browser and ACS administration Web service, with a random destination port. If an attacker spoofs the IP address of the user computer, and accesses the ACS GUI on this random port, then the attacker may be able to connect to the ACS GUI, bypassing authentication. Authentication to the ACS server may also be bypassed if the attacker is behind the same PAT device as that of the ACS user and accesses the ACS GUI on this random port.
    

Workarounds

• This section describes workarounds for these vulnerabilities.

  • Configure an IP address filter on ACS Windows and ACS Solution Engine to limit the exposure of these vulnerabilities. From within the ACS GUI, browse to Administration Control > Access Policy to limit access to only the machines that need to administer the ACS remotely.
    
  • Apply access control lists (ACLs) on routers, switches and firewalls that filter traffic to the ACS so that traffic is only allowed from stations that need to remotely administer the box. Refer to http://www.cisco.com/warp/public/707/tacl.html for examples on how to apply ACLs on Cisco routers.
    
  • As a best practice, use HTTPS to limit access to the Cisco ACS GUI. Issues detailed in CSCef05950 ( registered customers only) still exist when you use HTTP instead of HTTPS to access the Cisco ACS GUI.
    

  Refer to /en/US/products/sw/secursw/ps2086/products_user_guide_chapter09186a0080205a43.html#wp89030 for information on how to set up an access policy on the Cisco ACS.

Fixed Software

• 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.

  DDTs Bug ID	Impacted Versions	Fixed Versions	Platform
  CSCeb60017 ( registered customers only)	3.2(1), 3.2(2)	003.002(002.020) or later, 3.2(3) in Product Upgrade Tool	ACS Windows and ACS Solution Engine
  CSCec66913 ( registered customers only)	3.2(1), 3.2(2)	003.002(002.020) or later, 3.2(3) in Product Upgrade Tool	ACS Windows and ACS Solution Engine
  CSCec90317 ( registered customers only)	3.2(1)	003.002(002.005) or later, 3.2(2) in Product Upgrade Tool	ACS Windows and ACS Solution Engine
  CSCed81716 ( registered customers only)	3.2(1), 3.2(2)	003.002(003.011) or later, 3.2(3) in Product Upgrade Tool	ACS Solution Engine only
  CSCef05950 ( registered customers only)	3.0(x), 3.1(x), 3.2(x), 3.3(1)	There are patches available to address this vulnerability for versions 3.1(2), 3.2(3) and 3.3(1). See the Customers with Service Contracts section below for details on the location of these patches. Although version 3.0 is affected, the fix is only available with a feature set included in versions 3.1 and higher. Customers without Service Contracts will need to contact Cisco Technical Assistance Center at the numbers listed below for assistance.	ACS Windows and ACS Solution Engine

  Upgrade procedures can be found as indicated:

  • ACS Windows 3.3: http://www.cisco.com/en/US/docs/net_mgmt/cisco_secure_access_control_server_for_windows/3.3/installation/guide/windows/install.html#wp998991
    
  • ACS Windows 3.2: http://www.cisco.com/en/US/products/sw/secursw/ps2086/prod_installation_guide09186a0080184928.html#wp9472
    
  • ACS Solution Engine: http://www.cisco.com/en/US/products/sw/secursw/ps5338/products_user_guide_chapter09186a0080204d45.html#wp911224
    

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040825-acs

Revision History

• Revision 1.3	2007-August-14	Fixed link.
  Revision 1.2	2004-October-05	Clarified impact of Denial of Service vulnerabilities in the Impact section. Added the Impacted Versions column and added content to the Fixed Versions column in the Software Versions and Fixes section table. Clarified version 3.0(x) status in the Software Versions and Fixes section.
  Revision 1.1	2004-August-25	Changed URLs in the Obtaining Fixed Software section.
  Revision 1.0	2004-August-25	Initial public release.

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