[apops] Cisco Security Advisory: IOS HTTP Server Command Injection Vulne

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  • Subject: [apops] Cisco Security Advisory: IOS HTTP Server Command Injection Vulnerability
  • From: Cisco Systems Product Security Incident Response Team <psirt at cisco dot com>
  • Date: Thu, 01 Dec 2005 17:43:52 -0500
  • Cc: psirt at cisco dot com
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      Cisco Security Advisory: IOS HTTP Server Command Injection Vulnerability
      ========================================================================
      
      Document ID: 68322
      
      Advisory ID: cisco-sa-20051201-http
      
      http://www.cisco.com/warp/public/707/cisco-sa-20051201-http.shtml
      
      Revision 1.0
      
      For Public Release 2005 December 01 2100 UTC (GMT)
      
      - -----------------------------------------------------------------------
      
      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
      
      - -----------------------------------------------------------------------
      
      Summary
      =======
      
      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 client browser and
      potentially execute malicious commands against the device or other
      possible cross-site scripting attacks. Successful exploitation of this
      vulnerability requires that a user browse a page containing dynamic
      content in which HTML commands have been injected.
      
      Cisco will be making free software available to address this
      vulnerability for affected customers. There are workarounds available
      to mitigate the effects of the vulnerability.
      
      This advisory is posted at 
      http://www.cisco.com/warp/public/707/cisco-sa-20051201-http.shtml.
      
      Affected Products
      =================
      
      This security advisory applies to all Cisco products that run Cisco IOS
      Software versions 11.0 through 12.4 with the HTTP server enabled. A
      system which contains the IOS HTTP server or HTTP secure server, but
      does not have it enabled, is not affected.
      
      To determine if the HTTP server is running on your device, issue the
      "show ip http server status" and "show ip http server secure status"
      commands at the prompt and look for output similar to:
      
          Router>show ip http server status
          HTTP server status: Enabled
      
      
      If the device is not running the HTTP server, you should see output
      similar to:
      
          Router>show ip http server status
          HTTP server status: Disabled
      
      
      Any version of Cisco IOS prior to the versions which will be listed in
      the Fixed Software section below may be vulnerable.
      
      Cisco IOS XR is not affected.
      
      To determine the software running on a Cisco product, log in to the
      device and issue the "show version" command to display the system banner.
      Cisco IOS Software will identify itself as "Internetwork Operating
      System Software" or simply "IOS". On the next line of output, the image
      name will be displayed between parentheses, followed by "Version" and
      the IOS release name. Other Cisco devices will not have the "show
      version" command or will give different output.
      
      The following example identifies a Cisco product running IOS release
      12.3(6) with an installed image name of C3640-I-M:
      
          Cisco Internetwork Operating System Software
          IOS (tm) 3600 Software (C3640-I-M), Version 12.3(6), RELEASE SOFTWARE (fc3)
      
      
      The next example shows a product running IOS release 12.3(11)T3 with an
      image name of C3845-ADVIPSERVICESK9-M:
      
          Cisco IOS Software, 3800 Software (C3845-ADVIPSERVICESK9-M), Version 12.3(11)T3, RELEASE SOFTWARE (fc4)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2005 by Cisco Systems, Inc.
      
      
      Additional information about Cisco IOS release naming can be found at
      http://www.cisco.com/warp/public/620/1.html.
      
      No other Cisco products are currently known to be affected by the
      vulnerability addressed in this advisory.
      
      Details
      =======
      
      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.
      
      Impact
      ======
      
      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.
      
      Software Versions and Fixes
      ===========================
      
      No software fixes are currently available. This section will be updated
      regularly as soon as software fixes are available.
      
      Workarounds
      ===========
      
      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. Two typical services
      are WEB_EXEC and the IOS Certificate Server (SCEP). The WEB_EXEC
      service provides a facility to configure the box and retrieve current
      state of the box from remote clients. The IOS Certificate Server
      service provides a facility wherein remote clients can enroll and
      obtain Crypto Certificates.
      
      It is possible to disable the WEB_EXEC service while still leaving SCEP
      running to serve Certificates. If an installation requires the use of
      the SCEP service, the WEB_EXEC service may be disabled via the commands
      in configure mode:
      
          no ip http active-session-modules WEB_EXEC
          no ip http secure-active-session-modules WEB_EXEC
      
      
      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.
      
      Obtaining Fixed Software
      ========================
      
      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 at cisco dot com" or "security-alert at cisco dot 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 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 without Service Contracts
      +----------------------------------
      
      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 at cisco dot 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.
      
      Exploitation and Public Announcements
      =====================================
      
      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.
      
      The Cisco PSIRT is not aware of any malicious use of the vulnerability
      described in this advisory.
      
      Status of This Notice: INTERIM
      ==============================
      
      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. CISCO EXPECTS TO UPDATE THIS DOCUMENT WITHIN FROM
      THE ORIGINAL DATE OF THIS NOTICE.
      
      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://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 at cisco dot com
        * first-teams at first dot org
        * bugtraq at securityfocus dot com
        * vulnwatch at vulnwatch dot org
        * cisco at spot dot colorado dot edu
        * cisco-nsp at puck dot nether dot net
        * full-disclosure at lists.grok dot org dot uk
        * comp.dcom.sys.cisco at newsgate dot cisco dot 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-December-2005. | Initial  |
      | 1.0      |                  | draft.   |
      +----------------------------------------+
      
      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/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/.
      
      - -----------------------------------------------------------------------
      
      All contents are Copyright 1992-2005 Cisco Systems, Inc. All rights
      reserved. 
      - -----------------------------------------------------------------------
      
      Updated: Dec 01, 2005                                Document ID: 68322
      
      - -----------------------------------------------------------------------
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