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Cisco Security Response: Extensible Authentication Protocol
                         Vulnerability

http://www.cisco.com/warp/public/707/cisco-sr-20071019-eap.shtml

Revision 1.0
============

For Public Release 2007 October 19 1600 UTC (GMT)

- ---------------------------------------------------------------------

Cisco Response
==============

This is the Cisco PSIRT response to a presentation that was delivered
by Laurent Butti, Julien Tinnes and Franck Veysset of France Telecom
Group at Hack.lu on October 19th, 2007.

The presentation identifies a vulnerability in Cisco's implementation
of Extensible Authentication Protocol (EAP) that exists when
processing a crafted EAP Response Identity packet. This vulnerability
affects several Cisco products that have support for wired or
wireless EAP implementations.

The Cisco PSIRT team greatly appreciates the opportunity to work with
researchers on security vulnerabilities, and we welcome the
opportunity to review and assist in product reports.

This vulnerability is documented in the following Cisco bug IDs:

  * Wireless EAP - CSCsj56438
  * Wired EAP    - CSCsb45696 and CSCsc55249

This Cisco Security Response is available at the following link: 
http://www.cisco.com/warp/public/707/cisco-sr-20071019-eap.shtml.

Additional Information
======================

As described in RFC3748, EAP is an authentication framework that
supports multiple authentication methods. Typically, EAP runs
directly over data link layers, such as Point-to-Point Protocol (PPP)
or IEEE 802, without requiring IP.

Vulnerable Products
+------------------

This vulnerability affects both wired and wireless implementation on
Cisco devices.

EAP is not configured by default on any of these Cisco devices.

The following Cisco products support Wireless EAP and are affected by
this vulnerability (CSCsj56438):

  * Access Points and 1310 Wireless Bridges running Cisco IOS in
    autonomous mode.

    Access Points and 1310 Wireless Bridges running in LWAPP mode are
    not affected.

    To confirm if an Access Point runs Cisco IOS in autonomous mode,
    log into the device and issue the command line interface (CLI)
    command "show version | include IOS". Access Points in autonomous
    mode will have -K9W7- in the image names, while Access Points in
    LWAPP mode will have -K9W8- in their name. The example below
    shows an Access Point in autonomous mode:
   
        AP#show version | include IOS
        Cisco IOS Software, C1240 Software (C1240-K9W7-M), Version 12.4(3g)JA, RELEASE SOFTWARE (fc2)
        AP#
   
    To determine if EAP is enabled on the Access Point, log into the
    device and issue the "show running-config" CLI command. If the
    output contains the "authentication open eap <method_name>" or 
    "authentication network-eap <method_name>" then the device is
    vulnerable. The example below shows a vulnerable Access Point:
   
        AP#show running-config 
           ...
             dot11 ssid test
               authentication open eap eap_methods 
               authentication network-eap eap_methods 
               authentication key-management wpa
               guest-mode
               infrastructure-ssid optional
           ...
        AP#
   
    If an attacker successfully exploits this vulnerability against
    an Access Point, the device will reload. Repeated exploitation
    will result in a sustained Denial of Service (DoS) attack.

    This vulnerability was reported to Cisco by Laurent Butti and
    Benoit Stopin.

The following Cisco products support Wired EAP and are affected by
this vulnerability.

  * All Cisco switches running affected versions of Cisco IOS
    (CSCsb45696).

    Cisco switches are vulnerable if they run an EAP authenticator.
    EAP supplicants are not vulnerable.

    To determine if EAP authenticator is enabled on a switch, log
    into the device and issue the 
    "show running-config | include dot1x" CLI command. If the output
    contains either "dot1x pae authenticator" or "dot1x pae both",
    then the device is vulnerable to exploits via the interface
    where these commands appear. The example below shows a device
    that has EAP authenticator enabled:
   
        switch#show running-config | include dot1x
        dot1x system-auth-control 
         dot1x pae authenticator 
         dot1x port-control auto 
         dot1x timeout quiet-period 1
         dot1x timeout ratelimit-period 1
         dot1x max-start 10
         dot1x max-req 10
        switch#
   
    A related Cisco bug ID, CSCsi70426, exists and displays a
    traceback message on the console or syslogs when receiving the
    crafted EAP-ID-RESPONSE packet. However, the device will continue
    to operate.

  * All Cisco switches running affected versions of Cisco CatOS
    (CSCsc55249).

    Cisco switches are vulnerable if they run an EAP authenticator.
    EAP supplicants are not vulnerable.

    To determine if EAP authenticator is enabled on a switch, log
    into the device and issue the "show run all | include dot1x" CLI
    command. If the output contains both 
    "set dot1x system-auth-control enable" and any occurrence of
    "set port dot1x <mod/port> port-control auto", then the device is
    vulnerable for exploitation via the port where the 
    "set port dot1x" commands appear. An example is shown below of a
    device that has EAP authenticator enabled:
   
        Console> (enable) show run all | include dot1x 
            #dot1x 
            set dot1x system-auth-control enable 
            set dot1x quiet-period 60 
            set dot1x tx-period 30 
            set dot1x shutdown-timeout 300 
            set dot1x supp-timeout 30 
            set dot1x server-timeout 30 
            set dot1x max-req 2 
            set dot1x max-reauth-req 2 
            set dot1x re-authperiod 3600 
            set dot1x radius-accounting disable 
            set dot1x radius-vlan-assignment enable 
            set dot1x radius-keepalive enable 
            set dot1x critical-recovery-delay 100 
            set port dot1x 10/2 port-control auto 
        Console> (enable)
   
There are no workarounds for this vulnerability on wired or wireless
implementations of EAP.

Successful exploitation of the vulnerability on either the wired or
wireless device will result in a reload of the device. Repeated
exploitation could result in a sustained DoS attack.

The list below describes the affected trains and the first fixed
release:

+-------------------------------------------------------------------+
|                   Wireless EAP - CSCsj56438                       |
|-------------------------------------------------------------------|
| Affected Release    | First Fixed Releases                        |
|---------------------+---------------------------------------------|
| 12.3.JA             | Vulnerable;                                 |
|                     | For AP1100s & AP1200s migrate to            |
|                     | 12.3(8)JEC or later.                        |
|                     | For AP1130, AP1240, AP1310 & AP1410         |
|                     | migrate to 12.4(3g)JA2 or later.            |
|-------------------------------------------------------------------|
| 12.3.JEA            | Vulnerable; migrate to 12.3(8)JEC or later  |
|-------------------------------------------------------------------|
| 12.3.JEB            | Vulnerable; migrate to 12.3(8)JEC or later  |
|-------------------------------------------------------------------|
| 12.3.JEC            | 12.3(8)JEC or later; available 24-Oct-07    |
|-------------------------------------------------------------------|
| 12.4.JA             | 12.4(3g)JA2 or later                        |
+-------------------------------------------------------------------+

+-------------------------------------------------------------------+
|               Wired EAP (Cisco IOS) - CSCsb45696                  |
|-------------------------------------------------------------------|
| Affected Major Release | First Fixed Releases                     |
|------------------------+------------------------------------------|
|                        | 12.1(27b)E2 or later                     |
|                        |------------------------------------------|
| 12.1                   | 12.1(22)EA6 or later                     |
|                        |------------------------------------------|
|                        | 12.1(26)EB2 or later                     |
|------------------------+------------------------------------------|
|                        | 12.2(18)EW6 or later                     |
|                        |------------------------------------------|
|                        | 12.2(18)S13 or later                     |
|                        |------------------------------------------|
|                        | 12.2(18)SXF9 or later                    |
|                        |------------------------------------------|
|                        | 12.2.18-ZY1 or later                     |
|                        |------------------------------------------|
|                        | 12.2(20)S13 or later                     |
|                        |------------------------------------------|
|                        | 12.2(25)EWA4 or later                    |
| 12.2                   |------------------------------------------|
|                        | 12.2(25)EX or later                      |
|                        |------------------------------------------|
|                        | 12.2(25)FX or later                      |
|                        |------------------------------------------|
|                        | 12.2(25)SED or later                     |
|                        |------------------------------------------|
|                        | 12.2(25)SG or later                      |
|                        |------------------------------------------|
|                        | 12.2(31)SB6 or later                     |
|                        |------------------------------------------|
|                        | 12.2(33)SRA4 or later                    |
+-------------------------------------------------------------------+

+-------------------------------------------------------------------+
|           Wired EAP (Cisco CatOS) - CSCsc55249                    |
|-------------------------------------------------------------------|
| Affected Major Release | First Fixed Releases                     |
|------------------------+------------------------------------------|
| 6.x                    | Vulnerable; migrate to 8.5 or 8.6        |
|------------------------+------------------------------------------|
| 7.x                    | Vulnerable; migrate to 8.5 or 8.6        |
|------------------------+------------------------------------------|
|                        | 8.5(9) or later.                         |
| 8.x                    |------------------------------------------|
|                        | 8.6(1) or later.                         |
+-------------------------------------------------------------------+

No other Cisco IOS major release trains are known to be affected by
this vulnerability.

For more information on the terms "releases" and "trains," consult
the following URL:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_white_paper09186a008018305e.shtml

Products Confirmed Not Vulnerable
+--------------------------------

The following Cisco products that support the EAP framework have been
confirmed as not affected by this vulnerability:

  * Access Points
    - Access Points running VxWorks (cisco 1000s)
    - Lightweight Access Point (LAP) in local mode
    - Lightweight Access Point (LAP) in H-/REAP mode
    - 1310 Wireless Bridge operating in LWAPP mode
    - 1410 Wireless Bridge.
   
  * Wireless LAN Controllers
    - Cisco Airespace 3500 Series WLAN Controller
    - Cisco Airespace 4000 Series Wireless LAN Controller
    - Cisco 2000 series wireless LAN controllers
    - Cisco 2100 Series Wireless LAN Controllers
    - Cisco 4100 Series Wireless LAN Controllers
    - Cisco 4400 Series Wireless LAN Controllers
    - Cisco Wireless LAN Controller Module (NM-AIR-WLC6-K9)
    - Cisco Catalyst 3750 Series Integrated WLC
    - Cisco Catalyst 6500 Series WiSM
   
  * Wireless Integrated Routers (Wireless Access Point - Wireless EAP
    and Wired EAP)
    - Cisco 800 Series Routers
    - Cisco 1800 Series Integrated Services Routers
    - Cisco 2800 Series Integrated Services Routers
    - Cisco 3200 Series Wireless and Mobile Routers
    - Cisco 3800 Series Integrated Services Routers
   
  * Mobile Wireless
    - Cisco 521 Wireless Express Access Point (both as Autonomous AP
    and LWAPP)
    - Cisco 526 Wireless Express Mobility Controller

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.

Revision History
================

+---------------------------------------------------------+
| Revision 1.0 | 2007-October-19 | Initial Public Release |
+---------------------------------------------------------+

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.

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