Summary
Affected Products
Details
Impact
Software Version and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of this Notice: FINAL
Distribution
Revision History
Cisco Security Procedures
The default Cisco IOS configuration shipped with the Cisco Router Web Setup (CRWS) application allows the execution of commands at privilege level 15 through the Cisco IOS HTTP (Hypertext Transfer Protocol) server web interface without requiring authentication credentials. Privilege level 15 is the highest privilege level on Cisco IOS® devices.
Fixed versions of the CRWS application have been modified by Cisco to provide a more secure default IOS configuration and additional functionality with regards to the Cisco IOS HTTP server web interface.
This issue does not require a Cisco IOS software upgrade or a CRWS software upgrade. Customers who decide to upgrade to a fixed version of CRWS and deploy the new default IOS configuration will not need to deploy the suggested workarounds. Customers who elect NOT to upgrade to a fixed CRWS version, or customers upgrading to a fixed CRWS version who keep their existing configuration should implement the workarounds identified in this advisory.
Additional information on the new default IOS configuration shipped with the CRWS application is available in the Details section of this advisory.
This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20060712-crws.shtml.
The following Cisco routers whose configurations have been based on the default IOS configuration shipped with any version of CRWS prior to version 3.3.0 build 31 may be affected by this vulnerability:
Any of the previously listed Cisco routers whose IOS configuration is not based on the default IOS configuration shipped with the CRWS application are not vulnerable.
No other Cisco products are currently known to be affected by this vulnerability.
The Cisco Router Web Setup tool (CRWS) provides a graphical user interface (GUI) for configuring Cisco SOHO and Cisco 800 series routers, and allows users to set up their routers quickly and easily. The GUI is accessed through the Cisco IOS HTTP server, which is enabled on the default IOS configuration shipped with the CRWS application.
The Cisco IOS HTTP server uses the enable password (assuming one has been configured) as its default authentication mechanism. Other authentication mechanisms can be configured, including the use of a local user database, an external RADIUS (Remote Authentication Dial In User Service) or an external TACACS+ (Terminal Access Controller Access Control System) server. The default IOS configuration shipped with the CRWS application does not include an enable password or an enable secret command, allowing access to the Cisco IOS HTTP server interface at any privilege level, up to and including privilege level 15, without providing authentication credentials. Privilege level 15 is the highest privilege level on Cisco IOS devices.
To resolve this vulnerability, Cisco has made changes to the default IOS configuration shipped with the CRWS application and to the CRWS application itself. Those changes are as follows:
Note: CRWS will prompt the user to change those default credentials during its first invocation. It is strongly recommended for customers to remove those default credentials from the device configuration by using the Cisco IOS CLI (command line interface) if not planning to use the CRWS application for device configuration.
This vulnerability is documented by the following Cisco bug ID:
Note: Implementation of the available workarounds require manual configuration to mitigate the impact of this vulnerability for existing CRWS customers, even if upgrading to a fixed version of software.
Devices using CRWS for configuration and management are affected by this vulnerability if the following conditions are met:
The following procedure can be used to determine if a given device is vulnerable:
1. Is the Cisco IOS HTTP server enabled on the device?
2. Is there an authentication mechanism configured for access to the IOS HTTP server interface?
3. Is there an enable password or an enable secret configured on the device?
The following step-by-step procedure can be used in order to obtain the information needed to answer the questions in the previous procedure:
In order to determine if the Cisco IOS HTTP server is enabled on the device, execute the following command from a privileged CLI prompt:
show running-config | include ip http
The following example shows a device on which the Cisco IOS HTTP server is enabled:
Router#show running-config | include ip http ip http server Router#
The following example shows a device on which the Cisco IOS HTTP server is disabled:
Router#show running-config | include ip http no ip http server Router#
Note: Newer versions of the Cisco IOS HTTP server provide SSL (Secure Sockets Layer) encryption. This vulnerability can also be exploited if the SSL-enabled Cisco IOS HTTP server is enabled on the configuration. The following example shows a device on which the standard Cisco IOS HTTP server is disabled, but the SSL-enabled Cisco IOS HTTP server is enabled:
Router#show running-config | include ip http no ip http server ip http secure-server Router#
In order to determine if an authentication mechanism has been applied to the Cisco IOS HTTP server, execute the following command from a privileged CLI prompt:
show running-config | include ip http
The following example shows a device on which the Cisco IOS HTTP server is enabled and the local authentication mechanism has been configured:
Router#show running-config | include ip http ip http server ip http authentication local no ip http secure-server Router#
The absence of an ip http authentication line on the device configuration implies that the Cisco IOS HTTP server will use the enable secret or enable password (if so configured) as the authentication mechanism. Additional information on AAA mechanisms available for the Cisco IOS HTTP server can be found in the document entitled "AAA Control of the IOS HTTP Server", available at http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a008069bdc5.shtml.
In order to determine if an enable password or enable secret has been configured, execute the following command from a privileged CLI prompt:
show running-config | include enable [secret|password]
The following example shows a device on which an enable secret password has been configured:
Router#show running-config | include enable [secret|password] enable secret 5 $1$1yfp$qM7qAChXVXYp8ee2qm2Kf/ Router#
The following example shows a device on which no enable password or enable secret has been configured:
Router#show running-config | include enable [secret|password] Router#
Successful exploitation of this vulnerability may allow for the execution of commands on the device at any privilege level, up to and including privilege level 15. Accessing the device at privilege level 15 would enable total control of the device, including but not limited to device configuration changes and device reloading.
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.
This issue is fixed for new installations in CRWS version 3.3.0 build 31, which is available at http://www.cisco.com/pcgi-bin/tablebuild.pl/crws.
Devices shipped from Cisco manufacturing on or after August 8, 2006, include the fixed CRWS version 3.3.0 build 31.
Information about how to install CRWS version 3.3.0 build 31 can be found at http://www.cisco.com/en/US/products/sw/netmgtsw/ps2076/prod_troubleshooting_guide09186a0080132c3c.html#1080818.
Existing CRWS users or customers upgrading to CRWS version 3.3.0 build 31 from any previous version should deploy the workarounds mentioned in the Workarounds section of this security advisory. Upgrading the CRWS software on the device from a previous version to a fixed software version will not eliminate the vulnerability for existing installations.
There are multiple workarounds to mitigate this vulnerability. Existing CRWS customers, and customers upgrading to a new CRWS version from a previous one, should deploy one of the following workarounds if vulnerable to this issue. Upgrading to a new CRWS version is not enough to eliminate this vulnerability.
The second command might return an error message if the Cisco IOS version installed and running on the device does not support the SSL functionality. This error message is harmless and can be safely ignored.no ip http server no ip http secure-server
Replace <mypassword> with a strong password of your choosing. For guidance on strong passwords, please refer to your site security policy. The document entitled "Cisco IOS Password Encryption Facts", available at http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a00801d7efa.shtml, explains the differences between the enable secret and the enable password commands.enable secret <mypassword>
Note: The only authentication method tested and supported for use with the CRWS application is the local user database. No other methods (including the use of an external RADIUS or TACACS+ server) are supported.
In addition to those workarounds, it is highly recommended that customers limit access to their Cisco IOS HTTP server to only trusted management workstations. Information on how to restrict access to the Cisco IOS HTTP server based on IP addresses can be found at http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca734.html#1000973.
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.
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.
The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
This vulnerability was discovered during internal testing.
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.
This advisory is posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20060712-crws.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.
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.
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Revision 1.1 |
2006 August 10 1400 UTC (GMT) |
Added information on new devices including the fixed CRWS release. |
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Revision 1.0 |
2006 July 12 1600 UTC (GMT) |
Initial public release. |
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| Updated: Aug 10, 2006 | Document ID: 70650 |