VIGILANTe Security Watch Advisory

Name: Cisco Aironet AP1100 Valid Account Disclosure Vulnerability

Systems Affected: Tested on a Cisco Aironet AP1100 Model 1120B Series

Wireless device.

Firmware version 12.2(4)JA and earlier.

NB : A large number of Cisco IOSes are affected by this flaw.

Severity: High Risk

Vendor URL: http://www.vigilante.com

Authors: Reda Zitouni (reda.zitouni (at) vigilante (dot) com [email concealed])

Date: 28th July 2003

Advisory Code: VIGILANTE-2003002

Description

***********

Cisco Aironet 1100 Series Access Point is a device manufactured by Cisco

Systems offering a WLAN solution based on the 802.11b Wifi standard.

The Aironet Bridge is vulnerable to a Brute Force attack revealing if an

account exists or not.

Details

*******

A flaw in firmware version 12.2(4)JA and earlier allows a malicious

remote user to discover which accounts are valid on the targeted Cisco

Aironet Access Point by using classical brute force techniques.

Exploitation of this flaw is possible if the telnet service is enabled

with authentication.

If an attacker submits an existing account as login he will be then

prompted for the password. If not the case a ""% Login invalid" reply

will be displayed by the server, revealing the account is not existing.

By default on the Aironet AP1100, the 'cisco' account is set and is

prompted for a password when submitted. That default account then allows

an attacker to determine if this flaw on the remote device is patched or

not. This may lead to further serious attacks.

Vendor status:

**************

Cisco was contacted June 19, 2003 and answered the same day. 5 days

later, they told us that they would release a patch soon. The patch was

finally released July 3, 2003. Please note that this flaw is released by

Cisco as a Security Notice in CCO.

Vulnerability Assessment:

************************

A test case to detect this vulnerability was added to SecureScan NX in

the upgrade package of July 28, 2003. You can see the documentation of

this test case 15438 on SecureScan NX web site at

http://securescannx.vigilante.com/tc/15438.

Fix: A firmware upgrading the Aironet IOS version to c1100-k9w7 has been

released by Cisco. Please note that this version fixes some other bugs as

TC 17655 (refer to release note).

Workaround:

***********

Restrict access to your telnet service from outside your WLAN. A stronger

authentication mechanism, such as SSH can also be implemented.

CVE: Common Vulnerabilities and Exposures group ( reachable at

http://cve.mitre.org/ ) was contacted and assigned CAN-2003-0512 to this

vulnerability.

Links:

*****

Cisco Advisory: http://www.cisco.com/warp/public/707/cisco-sn-

20030724-ios-enum.shtml

Vigilante Advisory:

http://www.vigilante.com/inetsecurity/advisories/VIGILANTE-

2003002.htm

Product Homepage: http://www.cisco.com/warp/public/cc/pd/witc/ps4570

CVE: CAN-2003-0512 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-

CAN-2003-0512

Credit:

******

This vulnerability was discovered by Reda Zitouni, member of our Security

Watch Team at VIGILANTe.

We wish to thank Cisco PSIRT Team for their fast answer to fix this

problem.

Copyright VIGILANTe.com, Inc. 2003-07-28

Disclaimer:

**********

The information within this document may change without notice. Use of

this information constitutes acceptance for use in an AS IS condition.

There are NO warranties with regard to this information. In no event

shall the author be liable for any consequences whatsoever arising out of

or in connection with the use or spread of this information. Any use of

this information lays within the user's responsibility.

Feedback:

********

Please send suggestions, updates, and comments to

securitywatch (at) vigilante (dot) com [email concealed]

[ reply ]