[VulnWatch] Cisco Aironet AP1100 Valid Account Disclosure Vulnerability

From: Réda Zitouni (Reda.Zitouni_at_vigilante.com)
Date: 07/28/03

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    Date: Mon, 28 Jul 2003 18:12:56 +0200
    To: <bugtraq@securityfocus.com>

    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@vigilante.com)
    Date: 28th July 2003
    Advisory Code: VIGILANTE-2003002
    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.
    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
    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).
    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
    Cisco Advisory:
    Vigilante Advisory:
    Product Homepage: http://www.cisco.com/warp/public/cc/pd/witc/ps4570
    CVE: CAN-2003-0512

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