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@stake advisory: Multiple Red-M 1050 Blue Tooth Access Point Vulnerabilities
From: Dave Ahmad <da () securityfocus com>
Date: Fri, 7 Jun 2002 13:19:15 -0600 (MDT)


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                              @stake, Inc.
                            www.atstake.com

                           Security Advisory

Advisory Name: Multiple Red-M 1050 Blue Tooth Access Point Vulnerabilities
       Issues: Red-M 1050 Access Point Management Web Server DoS
               Red-M 1050 Access Point Case Insensitive Passwords
               Red-M 1050 Access Point TFTP Server Based Password Attack
               Red-M 1050 Access Point Management Session State Storage
               Red-M 1050 Access Point Device Existence Broadcast
               Red-M 1050 Access Point PPP Denial of Service
 Release Date: 06/05/2002
  Application: Red-M 1050AP (Bluetooth Access Point)
               1050AP boot     v01.03.16
               1050AP loader   v02.01.26
               1050AP software v02.00.26
     Platform: Red-M 1050AP
               1050AP basecard v00.00.01
     Severity: An attacker is able to disable the administration web server,
               crack the administration password via tftp (UDP), piggyback
               authorised administration connections when proxied or NAT
               addresses are in use, and locate device on network without
               requiring to scan the network to locate it.
       Author: Ollie Whitehouse [ollie () atstake com]
Vendor Status: Alerted (Response below)
CVE Candidate: CAN-2002-0393
               CAN-2002-0394
               CAN-2002-0395
               CAN-2002-0396
               CAN-2002-0397
               CAN-2002-0398
    Reference: www.atstake.com/research/advisories/2002/a060502-1.txt

Overview:

Red-M's (http://www.red-m.com) 1050AP (Bluetooth Access Point)
is the device which exists between legacy Ethernet networks and
Bluetooth 1.0/1.1 compatible devices looking to obtain IP network
access. Red-M's device is currently the only device which supports
piconet (multiple Bluetooth clients to one access point).

A number of vulnerabilities exist, which are outlined below, that
could enable an attacker on the wired or wireless side of the device to
mount an attack against the device in an attempt to locate the device,
cause loss of administration functionality or compromise the administration
interface.

[1] Red-M 1050 Access Point Management Web Server DoS

The 1050AP device provides a web based management interface to allow
configuration of the device. This web based management system has no
concept of authorised or unauthorised hosts and is simply protected by
a password over an unencrypted connection.

There exists a vulnerability in the web server that runs on the 1050AP that
potentially allows an attacker to disable the web server completely until
the device is restarted (physically).

[2] Red-M 1050 Access Point Case Insensitive passwords

Another existing vulnerability in the AP is that the administration
password is not case sensitive. This combined with the fact that the
maximum password length is 16 chars (documented) and can only be a-z,
0-9 (@stake testing) greatly reduces the number of passwords which can
be used and thus reduces cracking time.

[3] Red-M 1050 Access Point TFTP Sever Based Password Attack

In addition, the AP provides a tftp server for configuration backups
and firmware updates. This tftp server can not be disabled and can
be used by an attacker to crack the administration password using a UDP
based attack. This combined with the above can provide an effective way of
cracking the administration password in a short time by either dictionary
or brute force methods.

[4] Red-M 1050 Access Point Management Session State Storage

Their exists another vulnerability within the administration web interface.
When you login with the admin password to the web interface, no cookie,
session ID or basic authentication data are passed. No data is passed from
either the client to server or server to the client in response to maintain
state of the current session. The server simply remembers that your IP
successfully logged in until the session expires and/or you click the
logout button. This method of maintaining state suffers from a number of
attacks:

        I) You connect to the device via a proxy; then any user who uses
           the  same proxy can connect to the admin interface already
           authenticated.
        II) You connect to the device via a firewall which does NAT/PAT; then,
           as above, anyone who is NAT'd behind the same IP can get access to
           the admin interface.
        III) A number of other IP/Layer2 based attacks for traffic
           redirection or forged packets are possible.

This combined with the fact that when changing the administration password,
the device does not ask for the current password.  This means that an
Administrator can effectivly be locked out of the device by an attacker
sucessfully exploiting this vulnerability.

[5] Red-M 1050 Access Point Device Existence Broadcast

The device broadcasts its name via UDP to the broadcast address
(255.255.255.255). So to detect a Red-M AP active on the network simply
listen on UDP port 8887, and every minute or so a broadcast will occur
which delivers the following information: the AP's current name, IP address,
netmask, serial number and aerial address.

[6] Red-M 1050 Access Point PPP Denial of Service

Finally, it is possible for an attacker who is bonded to cause a denial of
service within the AP. Each attempt to connect thereafter will not work,
simply generating an error of 'Unable to establish a connection' within
the Microsoft dial-up connection dialog box.


Details:

It should be noted that although a number of issues are listed as
DoS-only, this is only limited by the fact that during the assessment of the
device @stake was unable to gain access to the debugging interface to
enable the successfull exploitation of the vulnerabilities (be they
buffer or heap overflows).

[1] Red-M 1050 Access Point Management Web Server DoS

Connect to the web interface and enter a long string for the administration
password. Click 'OK'. You will get a connect error on the page refresh and
the web server will be dead until you power down the device and restart it
physically.

[2] Red-M 1050 Access Point Case Insensitive passwords

The same file was requested twice using the different cases. In each case
the same file was returned. This can also be demonstrated within the web
interface by attempting to log-in with either the real password or a the
same password but using a different case (e.g. AbCdEf instead of abcdef).

        C:\>tftp -i 192.168.1.253 get FLASH_Database-abcdef
        Transfer successful: 381 bytes in 2 seconds, 190 bytes/s

        C:\>tftp -i 192.168.1.253 get FLASH_Database-AbCdEf FLASH_Second
        Transfer successful: 381 bytes in 3 seconds, 127 bytes/s

        C:\>fc FLASH_Database-abcdef FLASH_Second
        Comparing files FLASH_Database-abcdef and FLASG_Second
        FC: no differences encountered

[3] Red-M 1050 Access Point TFTP Sever Based Password Attack

Simply execute the following command replacing the <password> tag with the
attempted password.

        tftp -i 192.168.1.1 get FLASH_Database-<password>

[4] Red-M 1050 Access Point Management Session State Storage

A simple way to demonstrate this vulnerability is to use one browser (such
as IE) and authenticate with the management interface. Then load a different
browser (such as Netscape) and then type in the address of the AP. You will
be presented with the pre-authenticated administrative interface on the AP.

[5] Red-M 1050 Access Point Device Existence Broadcast

Use a tool such as netcat to listen on port UDP/8887 (i.e. nc -u -L -p 8887
 -o output). Every 30 seconds a new entry will be made in the log file similar
to the one below:

< 00000000 2c 01 be ba c0 a8 01 fd ff ff ff 00 00 02 81 64 # &....2.........d
< 00000010 00 56 02 06 08 01 00 00 00 0d 01 57 6f 6c 6c 79 # .V.........Wolly
< 00000020 57 6f 72 6c 64 00                               # World.

A break down of the packet is as follows:

        [bytes 1]               Length of data segment of packet
        [bytes 2 to 4]          Unknown
        [bytes 5 to 8]          IP address of device
        [bytes 9 to 12]         Subnet mask of device
        [bytes 13 to 15]        Serial Number*
        [bytes 16 to 18]        Bluetooth Address*
        [byte  19]              Is the device configured (01 = no / 02 = yes)
        [bytes 20 to 27]        Unknown
        [bytes 28 to LEN-1]     Access point name

The above packet is how Red-M's own set up program knows of the AP's
existence on the network.

* [bytes 13 to 18] the aerial address

[6] Red-M 1050 Access Point PPP Denial of Service

Bond and then connect with the AP. When prompted for the PPP username for
the link enter a very long username.


Recommendation:

Upgrade your firmware to the latest release. In addition follow
the steps outlined below to mitigate the current design vulnerabilities.

Typically, wireless access points to the network should be considered
hostile networks. In the case of the above vulnerabilities a packet filtering
device should be placed between the Ethernet interface of the AP and the
corporate network restricting the types of traffic and from which hosts
communication destined for the AP can come from. However this will still
expose the device to attacks from the wireless side of the device. To
guard against these attacks, ensure that good username and password policies
are in place. However, consider the limitations of the username and
passwords in the 1050AP. Strong passwords may not be possible. From @stake's
testing, usernames and passwords can only be [a-z] and [0-9] within the
device's PPP authentication mechanism.

The 1050AP does provide a number of other mechanisms to protect against
being discovered and to protect against automatic connections. For details
of these please refer to the vendor's documentation. It is @stake's
recommendation that the following options are used:

        [Option]                        [Suggested Setting]
        Authentication:                 Authentication with bonding
        Force encryption:               Check box
        Accessibility mode:             Connectable and non discoverable
        PPP authentication:             Check box
        Automatically authorize:        Uncheck box


Vendor Response:

Red-M was initially notified of these vulnerabilities between August and
November, 2001.

It should be noted the DoS attacks have been resolved in the latest
release of the firmware available from the Red-M website:

http://www.red-m.com/Products/Downloads/freefiles/1050AP_2_02_10.zip

The remaining design issues are due to be resolved in a firmware
release planned for August, 2002.

The following response was received from Red-M via email.

"We continue to see the principle new threat introduced by the
addition of a wireless access point as being from outside that network,
over the wireless(Bluetooth) interface, or an external connection to the
wired network (typically the Internet). This is continuously re-enforced
by the customer feedback we receive. We believe that your draft advisory
does not demonstrate a practical vulnerability over the *wireless*
interface, as the 1050AP's wireless security mechanisms (Bluetooth security)
has not been shown to be vulnerable. The vulnerabilities that you have
identified require that 1050AP is installed in an environment where the
corporate security policy allows such attacks to be mounted on the wired
side of the Access Point.

The current design philosophy for the 1050AP is that it would be used on a
corporate network already secured by implementation of a corporate security
policy. This should mitigate the risk of attacks from the wired network. We
have thus concentrated on meeting the customer requirement of securing
access to the wired network from the wireless side by, for example, rogue
Bluetooth devices.

However, we also realise that a level of security is required to mitigate
some types of attack from inside the wired network, and to prevent
accidental compromising of wireless connectivity. The issues you've raised
we believe fit into this category. Revised firmware to address the issues
you raised is now planned for the firmware release in August. This firmware
will be applied both to new build of product and made available for the
installed base as an upgrade that can be applied to product that's already
in use."


Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has
assigned the following names to these issues.  These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

 CAN-2002-0393 Red-M 1050 Access Point Management Web Server DoS
 CAN-2002-0394 Red-M 1050 Access Point Case Insensitive Passwords
 CAN-2002-0395 Red-M 1050 Access Point TFTP Server Based Password Attack
 CAN-2002-0396 Red-M 1050 Access Point Management Session State Storage
 CAN-2002-0397 Red-M 1050 Access Point Device Existence Broadcast
 CAN-2002-0398 Red-M 1050 Access Point PPP Denial of Service

@stake Vulnerability Reporting Policy:
http://www.atstake.com/research/policy/

@stake Advisory Archive:
http://www.atstake.com/research/advisories/

PGP Key:
http://www.atstake.com/research/pgp_key.asc

Copyright 2002 @stake, Inc. All rights reserved.

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Dave Ahmad
SecurityFocus
www.securityfocus.com



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