Products & Services

Contents

Summary
Affected Products
Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: INTERIM
Distribution
Revision History
Cisco Security Procedures

This section provides details on affected products.

Vulnerable Products

Products Confirmed Not Vulnerable

The Cisco IOS Web browser interface (which enables the device to perform as an HTTP server) allows configuration and monitoring of a router or access server using any web browser. This feature was introduced in IOS 11.0.

A vulnerability exists in the IOS HTTP server in which HTML code inserted into dynamically generated output, such as the output from a show buffers command, will be passed to the browser requesting the page. This HTML code could be interpreted by the browser and potentially execute malicious commands against the device or other possible cross-site scripting attacks.

In order to be vulnerable to the cross-site scripting attack, a user must browse and view the content during the same period of time the injected code exists in memory. On the other hand, if a user does not browse contaminated dynamic content on the device, then exploitation is not possible.

A proof of concept exploit exists for this vulnerability, in which the exploit attempts to reset the enable password on the device. For the attack to work against the device itself, the user browsing tainted dynamic content on the router will only be able to execute commands at or below the privilege level for which they are authenticated and authorized for on the device.

This vulnerability is documented in Cisco Bug ID CSCsc64976 ( registered customers only) .

Successful exploitation of the vulnerability may result in an attacker executing commands on the device, including the possibility of gaining full administrative privileges on the device which is dependent on the privilege level of the authenticated user.

No software fixes are currently available. This section will be updated regularly as soon as software fixes are available.

Disable the HTTP Server

If the HTTP server is not used for any legitimate purposes on the device, it is a best practice to disable it by issuing the following commands in configure mode:

no ip http server
no ip http secure-server

Disable the HTTP WEB_EXEC Service

A feature was introduced in 12.3(14)T and later in which selective HTTP and HTTPS services could be enabled or disabled. The WEB_EXEC service provides a facility to configure the box and retrieve the current state of the box from remote clients.

It is possible to disable the WEB_EXEC service while still leaving other HTTP services active. If an installation does not require the use of the WEB_EXEC service, then it may be disabled using the following procedure:

1. Verify the list of all session modules.
   

   Router#show ip http server session-module 
   HTTP server application session modules: 
    Session module Name  Handle Status   Secure-status  Description 
   HTTP_IFS              1      Active   Active         HTTP based IOS File Server 
   HOME_PAGE             2      Active   Active         IOS Homepage Server 
   QDM                   3      Active   Active         QOS Device Manager Server 
   QDM_SA                4      Active   Active         QOS Device Manager Signed Applet Server 
   WEB_EXEC              5      Active   Active         HTTP based IOS EXEC Server 
   IXI                   6      Active   Active         IOS XML Infra Application Server 
   IDCONF                7      Active   Active         IDCONF HTTP(S) Server 
   XSM                   8      Active   Active         XML Session Manager 
   VDM                   9      Active   Active         VPN Device Manager Server 
   XML_Api               10     Active   Active         XML Api 
   ITS                   11     Active   Active         IOS Telephony Service 
   ITS_LOCDIR            12     Active   Active         ITS Local Directory Search 
   CME_SERVICE_URL       13     Active   Active         CME Service URL 
   CME_AUTH_SRV_LOGIN    14     Active   Active         CME Authentication Server 
   IPS_SDEE              15     Active   Active         IOS IPS SDEE Server 
   tti-petitioner        16     Active   Active         TTI Petitioner

2. Create a list of session modules that are required, in this example it would be everything other than WEB_EXEC.
   

   Router#configuration terminal
   Router(config)#ip http session-module-list exclude_webexec 
                HTTP_IFS,HOME_PAGE,QDM,QDM_SA,IXI,IDCONF,XSM,VDM,XML_Api,
                ITS,ITS_LOCDIR,CME_SERVICE_URL,CME_AUTH_SRV_LOGIN,IPS_SDEE,tti-petitioner
   

3. Selectively enable HTTP/HTTPS applications that will service incoming HTTP requests from remote clients.
   

   Router(config)#ip http active-session-modules exclude_webexec 
   Router(config)#ip http secure-active-session-modules exclude_webexec 
   Router(config)#exit 
   

4. Verify the list of all session modules, and ensure WEB_EXEC is not active.
   

   Router#show ip http server session-module 
   HTTP server application session modules: 
    Session module Name  Handle Status   Secure-status  Description 
   HTTP_IFS              1      Active   Active         HTTP based IOS File Server 
   HOME_PAGE             2      Active   Active         IOS Homepage Server 
   QDM                   3      Active   Active         QOS Device Manager Server 
   QDM_SA                4      Active   Active         QOS Device Manager Signed Applet Server 
   WEB_EXEC              5      Inactive Inactive       HTTP based IOS EXEC Server 
   IXI                   6      Active   Active         IOS XML Infra Application Server 
   IDCONF                7      Active   Active         IDCONF HTTP(S) Server 
   XSM                   8      Active   Active         XML Session Manager 
   VDM                   9      Active   Active         VPN Device Manager Server 
   XML_Api               10     Active   Active         XML Api 
   ITS                   11     Active   Active         IOS Telephony Service 
   ITS_LOCDIR            12     Active   Active         ITS Local Directory Search 
   CME_SERVICE_URL       13     Active   Active         CME Service URL 
   CME_AUTH_SRV_LOGIN    14     Active   Active         CME Authentication Server 
   IPS_SDEE              15     Active   Active         IOS IPS SDEE Server 
   tti-petitioner        16     Active   Active         TTI Petitioner 

For further information on selective enabling of applications using an HTTP or secure HTTP server, consult the Cisco IOS network management configuration guide, release 12.4T at: http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_http_app_enable.html

Avoid the use of Web-based SHOW commands

Successful exploitation of this vulnerability requires an unsuspecting user to request dynamic content from the device via the "show" commands which are available. Avoiding the use of those commands via the web interface until an upgrade to fixed software is possible may be perfectly legitimate for some installations.

Cisco will make free software available to address this vulnerability for affected customers. This advisory will be updated as fixed software becomes available. 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/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades.

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 whose Cisco products are provided or maintained through prior or existing agreement 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 who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their 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
  

Have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.

This vulnerability was disclosed in a public posting to the Bugtraq mailing list, and at the following URL: http://www.infohacking.com/INFOHACKING_RESEARCH/Our_Advisories/cisco/index.html .

We would like to thank iDefense for finding and initially reporting this vulnerability to us.

We would also like to thank Mr. Adrian Pastor from ProCheckup Ltd for sharing information with us about another possible vector into this vulnerability. His research paper is available at http://www.procheckup.com/vulnerability_manager/vulnerabilities/paper-04 .

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

This advisory is posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20051201-http.shtml.

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.

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/en/US/products/products_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/.