HTTP GET Vulnerability in AP1x00

Summary

• A vulnerability has been reported by an external researcher in Cisco IOS^® release for Cisco Aironet AP1x00 Series Wireless devices. The vulnerability affects only IOS-based Cisco Aironet Wireless products. The VxWorks based Cisco Aironet Wireless Devices are not affected. This vulnerability can cause the AP1x00 to reload and is documented as Cisco bug ID CSCeb49869 ( registered customers only) (also CAN-2003-0511). There are workarounds available to mitigate the effects of this vulnerability.

  This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20030728-ap1x00.

  The external report can be found at http://www.vigilante.com/inetsecurity/advisories/VIGILANTE-2003001.htm . A second external report found at http://www.vigilante.com/inetsecurity/advisories/VIGILANTE-2003002.htm details another issue, Cisco bug ID CSCdz29724 ( registered customers only) , which is present in all IOS software and is duplicated by the AP1x00 specific Cisco bug ID CSCeb49842 ( registered customers only) (also CAN-2003-512). More details on it can be found at http://www.cisco.com/warp/public/707/cisco-sn-20030724-ios-enum.shtml.

Affected Products

• This section provides details on affected products.

  Vulnerable Products

  Only the following Cisco IOS-based wireless Access Points are affected:

  Hardware Model	Software Release(s)
  Cisco Aironet Wireless Access Point AP1100 series	12.2(4)JA, 12.2(4)JA1, 12.2(8)JA, 12.2(11)JA
  Cisco Aironet Wireless Access Point AP1200 series	12.2(8)JA, 12.2(11)JA
  Cisco Aironet Wireless Bridge AP1400 series	12.2(11)JA

  All previous VxWorks-based software releases for Cisco Aironet Access Point 1200 are not affected. That includes the following, and earlier, software releases: 11.56, 12.01T1, 12.02T1, 12.03T.

  In order to determine your software release you should log on the Access Point using any account available and execute the following command:

  access-point> show ver
  
  Cisco Internetwork Operating System Software
  IOS (tm) C1100 Software (C1100-K9W7-M), Version 12.2(8)JA, EARLY
  DEPLOYMENT RELEASE SOFTWARE (fc1)               ^^^^^^^^^
  TAC Support: http://www.cisco.com/tac
  Copyright (c) 1986-2003 by cisco Systems, Inc.

  The Cisco IOS software version is displayed in the second line of the output. In this example it is 12.2(8)JA.

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by these vulnerabilities.

Details

• Sending a malformed URL to the Cisco Aironet AP1x00 can cause the device to reload.

Workarounds

• There are two workarounds for this vulnerability. One is to use access-class or access-list commands to limit the access to legitimate hosts only, and another workaround is to disable HTTP and use SSH to administer the Cisco Aironet Access Point.

  The example of using access-class is given here:

  ap(config)# ip http access-class 10
  ap(config)# access-list 10 permit host 10.0.0.1
  

  In this example, host 10.0.0.1 is the only one that is allowed to access the AP. All other hosts are prohibited.

  To disable HTTP and enable SSH use this example:

  ap(config)# no ip http server
  ap(config)# ip domain name 
  ap(config)# crypto key generate rsa
  The name for the keys will be: ap.your-domain
  Choose the size of the key modulus in the range of 360 to 2048 for your
   General Purpose Keys. Choosing a key modulus greater than 512 may take
   a few minutes.
  
  How many bits in the modulus [512]: 1024
  % Generating 1024 bit RSA keys ...[OK]
  ap(config)# line vty 0 4
  ap(config-line)# transport input ssh
  

  Now you can connect to the Cisco Aironet AP using SSH client from your computer. There are many free and commercial versions of SSH software available.

  In addition to the workarounds it is possible to mitigate the exposure by configuring ACLs on the device so that only legitimate hosts can use the http service. This can be done in the following way:

  access-list 111 permit tcp host 10.0.0.1 host 10.0.0.50 eq www
  

  In this example the host 10.0.0.1 is the only one that is allowed to access the device at 10.0.0.50. You will have to change host IP addresses and the ACL number to suit your configuration. This ACL will have to be applied to all interfaces and block all IP addresses assigned to the affected device.

Fixed Software

• The vulnerability is fixed in the 12.2(11)JA1 version of the software for all Cisco Aironet AP1x00 devices.

Exploitation and Public Announcements

• This vulnerability is reported by Reda Zitouni from Vigilante. Their report can be found at http://www.vigilante.com/inetsecurity/advisories/VIGILANTE-2003001.htm .

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

URL

• http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20030728-ap1x00

Revision History

• Revision 1.0	2003-July-28 16:00 UTC (GMT)	Initial public release.
  Revision 1.1	2003-July-28 18:30 UTC (GMT)	Corrected external report URLs.

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