Summary
Affected Products
Details
Impact
Software Versions and Fixes
Obtaining Fixed Software
Workarounds
Exploitation and Public Announcements
Status of This Notice: FINAL
Distribution
Revision History
Cisco Security Procedures
The Cisco IOS Firewall Authentication Proxy for FTP and/or Telnet Sessions feature in specific versions of Cisco IOS software is vulnerable to a remotely-exploitable buffer overflow condition.
Devices that do not support, or are not configured for Firewall Authentication Proxy for FTP and/or Telnet Services are not affected.
Devices configured with only Authentication Proxy for HTTP and/or HTTPS are not affected.
Only devices running certain versions of Cisco IOS® are affected.
Cisco has made free software available to address this vulnerability. There are workarounds available to mitigate the effects of the vulnerability.
This advisory will be posted at http://www.cisco.com/warp/public/707/cisco-sa-20050907-auth_proxy.shtml.
Devices that are running the following release trains of Cisco IOS are affected if Firewall Authentication Proxy for FTP and/or Telnet Sessions is configured and applied to an active interface.
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 Cisco IOS release name. Other Cisco devices will not have the show version command, or will give different output.
The following example identifies a Cisco 7200 router running Cisco IOS release 12.3(10a) with an installed image name of C7200-JK8O3S-M.
Router# show version Cisco Internetwork Operating System Software IOS (tm) 7200 Software (C7200-JK8O3S-M), Version 12.3(10a), RELEASE SOFTWARE (fc2) Copyright (c) 1986-2004 by cisco Systems, Inc.
Additional information about Cisco IOS release naming can be found at http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_white_paper09186a008018305e.shtml.
Refer to the Details section for more information about affected and unaffected configurations.
No other Cisco products are currently known to be affected by this vulnerability.
The Cisco IOS Firewall Authentication Proxy feature allows network administrators to apply specific security policies on a per-user basis. With the Firewall Authentication Proxy for FTP and/or Telnet Sessions feature, users can log into the network services via FTP and/or Telnet, and their specific access profiles are automatically retrieved and applied from a Remote Authentication Dial In User Service (RADIUS), or Terminal Access Controller Access Control System Plus (TACACS+) authentication server.
Cisco IOS Software is vulnerable to a Denial of Service (DoS) and potentially an arbitrary code execution attack when processing the user authentication credentials from an Authentication Proxy Telnet/FTP session. To exploit this vulnerability an attacker must first complete a TCP connection to the IOS device running affected software and receive an auth-proxy authentication prompt.
This vulnerability is documented in the Cisco Bug Toolkit as Bug ID
CSCsa54608
(
registered customers only)
.
To determine if your device is running the Firewall Authentication Proxy for FTP and/or Telnet Sessions feature, log into the device and issue the show ip auth-proxy configuration command to display the configuration of Firewall Authentication Proxy services. The following example identifies Firewall Authentication Proxy services running for Telnet and FTP under the proxy rule name proxy_example.
Router# show ip auth-proxy configuration Authentication global cache time is 60 minutes Authentication global absolute time is 0 minutes Authentication Proxy Watch-list is disabled Authentication Proxy Rule Configuration Auth-proxy name proxy_example ftp list not specified auth-cache-time 60 minutes telnet list not specified auth-cache-time 60 minutes
The following will be seen if Firewall Authentication Proxy services are not enabled but supported in your IOS version:
Router# show ip auth-proxy configuration Authentication global cache time is 60 minutes Authentication global absolute time is 0 minutes Authentication Proxy Watch-list is disabled Router#
The following will be seen if running a version of IOS that does not support Firewall Authentication Proxy services:
Router# show ip auth-proxy configuration
^
% Invalid input detected at '^' marker.
Router#
A router that has Firewall Authentication Proxy services assigned to an interface will have ip auth-proxy list name command under an interface in the show running-config output.
The following example identifies Firewall Authentication Proxy services running under the proxy rule name "proxy_example" applied to the interface Ethernet 2/1:
Router# show ip auth-proxy configuration
Authentication global cache time is 60 minutes
Authentication global absolute time is 0 minutes
Authentication Proxy Watch-list is disabled
Authentication Proxy Rule Configuration
Auth-proxy name proxy_example
ftp list not specified auth-cache-time 60 minutes
telnet list not specified auth-cache-time 60 minutes
Router# show running-config
.
.
!
interface Ethernet2/1
ip address 10.1.1.1 255.255.255.0
ip auth-proxy proxy_example
!
.
.
Additional information about Cisco IOS Firewall Authentication Proxy services refer to: http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/iosfw2/iosfw2_1.htm.
Additional information about Cisco IOS Firewall Authentication Proxy for FTP and/or Telnet Sessions refer to: http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123newft/123_1/ftp_tel.htm
Successful exploitation of the vulnerability on Cisco IOS may result in a reload of the device or execution of arbitrary code. Repeated exploitation could result in a sustained DoS attack or execution of arbitrary code on Cisco IOS devices.
When considering software upgrades, please also consult http://www.cisco.com/en/US/products/products_security_advisories_listing.html 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") for assistance.
Each row of the Cisco IOS software table (below) describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix (the "First Fixed Release") and the anticipated date of availability for each are listed in the "Rebuild" and "Maintenance" columns. A device running a release in the given train 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).
For further information on the terms "Rebuild" and "Maintenance", please consult the following URL: http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_white_paper09186a008018305e.shtml.
|
Major Release |
Availability of Repaired Releases |
|
|---|---|---|
|
Affected 12.2-Based Release |
Rebuild |
Maintenance |
|
12.2SG |
Vulnerable; contact TAC |
|
|
12.2SEC |
Vulnerable; contact TAC |
|
|
12.2SXF |
Vulnerable; contact TAC |
|
|
12.2SH |
Vulnerable; 12.2(13)ZH8, available 25-Oct-05 |
|
|
12.2ZF |
Vulnerable; migrate to 12.3T or later |
|
|
12.2ZL |
Vulnerable; migrate to 12.3(4)XK4 or later for Cisco 17xx; migrate to 12.4(1) or later for Cisco 3200; migrate to 12.3(7)XR4 or later for ICS7750. |
|
|
Affected 12.3-Based Release |
Rebuild |
Maintenance |
|
12.3 |
12.3(3h) |
|
|
12.3(5e) |
||
|
12.3(6e) |
||
|
12.3(9d) |
||
|
12.3(10d) |
||
|
12.3(12b) |
||
|
12.3(13a) |
12.3(15) |
|
|
12.3B |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3BC |
12.3(9a)BC7; available 19-Sept-05 |
|
|
12.3BW |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3JA |
12.3(7)JA |
|
|
12.3JK |
12.3(2)JK |
|
|
12.3T |
12.3(7)T10 |
|
|
12.3(8)T9 |
||
|
12.3(11)T6 |
||
|
12.3(14)T2 |
||
|
12.3XA |
12.3(2)XA5; available TBD |
|
|
12.3XB |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3XC |
12.3(2)XC3 |
|
|
12.3XD |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3XE |
12.3(2)XE4; available TBD |
|
|
12.3XF |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3XG |
12.3(4)XG5; available TBD |
|
|
12.3XH |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3XI |
12.3(7)XI4 |
|
|
12.3XJ |
Vulnerable; migrate to 12.3(11)YF2 or later |
|
|
12.3XK |
12.3(4)XK4; available TBD |
|
|
12.3XL |
12.3(11)XL3 |
|
|
12.3XM |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3XQ |
Vulnerable; migrate to 12.4(1) or later |
|
|
12.3XR |
12.3(7)XR4 |
|
|
12.3XS |
Vulnerable; migrate to 12.4(1) or later |
|
|
12.3XU |
Vulnerable; contact TAC |
|
|
12.3XW |
Vulnerable; migrate to 12.3(11)YF2 or later |
|
|
12.3XY |
Vulnerable; contact TAC |
|
|
12.3YA |
Vulnerable; migrate to 12.4(1) or later for Cisco 828; migrate to 12.3(8)YG2 or later for SOHO 9x, Cisco 83x |
|
|
12.3YD |
Vulnerable; migrate to 12.3(14)T2 or later |
|
|
12.3YF |
12.3(11)YF2 |
|
|
12.3YG |
12.3(8)YG2 |
|
|
12.3YI |
12.3(8)YI1 |
|
|
12.3YJ |
Vulnerable; contact TAC |
|
|
12.3YK |
12.3(11)YK1 |
|
|
12.3YQ |
12.3(14)YQ |
|
|
12.3YS |
12.3(11)YS |
|
|
12.3YT |
12.3(14)YT |
|
|
12.3YU |
12.3(14)YU |
|
|
12.3YW |
12.3(11)YW |
|
|
Affected 12.4-Based Release |
Rebuild |
Maintenance |
|
12.4 |
12.4(1) |
|
|
12.4MR |
12.4(2)MR |
|
|
12.4T |
12.4(2)T |
|
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 assistance with the upgrade, which should be free of charge.
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.
Please 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.
Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades.
See 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.
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.
The effectiveness of any workaround 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 is the most appropriate for use in the intended network before it is deployed.
Additional auth-proxy and web server configuration settings are available. For details see http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/iosfw2/iosfw2_1.htm! Configure auth-proxy for http session authentication ip auth-proxy name http-proxy http ! Configure the router's web server to service auth-proxy authentication attempts ip http server ! Set the HTTP server authentication method to AAA ip http authentication aaa
priv-lvl=15 proxyacl#1=permit icmp any any proxyacl#2=permit tcp any any proxyacl#3=permit udp any any
Not all of the mitigation strategies listed will work for all customers. Some of the workarounds listed are dependent on which versions and feature-sets of IOS you have in your network. These mitigation strategies, may help reduce exposure to this vulnerability. To eliminate exposure to this vulnerability, customers should apply one of the workarounds listed above, or upgrade to a fixed release of Cisco IOS.
For further information on creating IP access lists, refer to Protecting Your Core: Infrastructure Protection Access Control Lists, at http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml, and Transit Access Control Lists: Filtering at Your Edge, at http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801afc76.shtml.! Permit trusted network 169.160.160.0/24 to access auth-proxy access-list 105 permit tcp 169.160.160.0 0.0.0.255 any eq telnet ! ! Deny all IP traffic that is not authenticated by auth-proxy ! Note: Management and Control traffic to the router itself would ! need to be allowed in this access-list access-list 106 deny ip any any ! ! Modify the telnet auth-proxy config to use access-list 105 ip auth-proxy name tel-proxy telnet inactivity-time 60 list 105 ! ! Apply interface access-list 106 and auth-proxy test interface FastEthernet1/0 ip address 10.66.65.47 255.255.255.0 ip access-group 106 in ip auth-proxy tel-proxy
! Do not police Telnet from trusted management host 169.160.160.1 to the auth-proxy router access-list 105 remark ** Do not police telnet from Trusted Hosts to Auth-Proxy Router ** access-list 105 deny tcp host 169.160.160.1 host 172.16.1.1 eq telnet access-list 105 deny tcp host 172.168.1.1 host 1.1.1.1 eq telnet access-list 105 deny tcp host 172.168.1.1 host 10.66.65.47 eq telnet ! ! Police all other telnet and ftp connections to the auth-proxy router access-list 105 remark ** Police all other telnet/ftp attempts to Auth-Proxy Router ** access-list 105 permit tcp any host 172.16.1.1 eq telnet access-list 105 permit tcp any host 1.1.1.1 eq telnet access-list 105 permit tcp any host 10.66.65.47 eq telnet access-list 105 permit tcp any host 172.16.1.1 eq ftp access-list 105 permit tcp any host 1.1.1.1 eq ftp access-list 105 permit tcp any host 10.66.65.47 eq ftp ! ! Allow telnet and ftp auth-proxy for trusted network 169.160.160.0/24 access-list 105 remark ** Allow Auth-Proxy sessions from trusted networks ** access-list 105 deny tcp 169.160.160.0 0.0.0.255 any eq telnet access-list 105 deny tcp 169.160.160.0 0.0.0.255 any eq ftp ! ! Allow telnet and ftp auth-proxy for trusted network back to 169.160.160.0/24 access-list 105 remark ** Allow Auth-Proxy sessions to trusted networks ** access-list 105 deny tcp host 172.168.1.1 169.160.160.0 0.0.0.255 ! ! Allow TACACS+ from ACS server 10.66.79.229 access-list 105 remark ** Ensure we can still communicate with TACACS+ Server ** access-list 105 deny tcp host 10.66.79.229 gt 1023 host 10.66.65.47 eq 49 access-list 105 deny tcp host 10.66.79.229 eq 49 host 10.66.65.47 gt 1023 ! ! Police all TCP based management traffic from un-trusted hosts ! Note: If BGP is configured it would need to be allowed before this access-list entry access-list 105 remark ** Drop any other TCP connections ** access-list 105 permit tcp any any ! ! Do not police any other type of traffic going to the router access-list 105 remark ** Rest do not police ** access-list 105 deny ip any any ! class-map match-all only-allow-trusted-hosts match access-group 105 ! policy-map control-plane-policy ! Drop all traffic that matches the class "only-allow-trusted-hosts" class only-allow-trusted-hosts drop ! control-plane service-policy input control-plane-policy
Note: CoPP is available only in IOS release trains 12.0S, 12.2S and 12.3T. Additional information on the configuration and use of the CoPP feature can be found at the following URL: http://www.cisco.com/en/US/products/sw/iosswrel/ps1838/prod_white_papers_list.html
Since the initial posting of this document, the Cisco PSIRT has been made aware of public announcements of the vulnerabilities described in this advisory. Cisco PSIRT is aware that the exploit for this vulnerability has been published on a public mailing list.
THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY TIME.
A stand-alone copy or paraphrase of the text of this security advisory that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This advisory will be posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20050907-auth_proxy.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.
|
Revision 1.3 |
2005-October-12 |
Updated Exploitation and Public Announcements section and all 12.2 references in Affected Products. |
|
Revision 1.2 |
2005-September-26 |
In Software Versions and Fixes table: 12.2ZH changed to 12.2SH, added 12.2ZF. |
|
Revision 1.1 |
2005-September-22 |
Added 12.2SG, 12.2SEC, and 12.2SXF releases to Software Version and Fixes table. |
|
Revision 1.0 |
2005-September-07 |
Initial public release |
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. Important Notices and Privacy Statement.
| Updated: Oct 12, 2005 | Document ID: 66269 |