This message cointains technical details about recenly published 
vulnerabilites in Wireless IDS (http://www.securityfocus.com/bid/20602, 
http://www.securityfocus.com/bid/20605) 


Web-style Wireless IDS attacks
by Sergey Gordeychik

gordey   ptsecurity.com

Article in PDF:
http://maxpatrol.com/webwids.asp 


Introduction

Wireless intrusion detection systems (WIDS) are not yet as popular as their
wired counterparts, but current trends would suggest that their number is
set to grow. One positive factor in this respect is the integration of such
programs with active network equipment and Management awareness of the
risks associated with the unauthorised use of wireless devices. This
awareness has led to an increase in the number of WIDS installations - even
where wireless networks are not used.

In view of this situation, specialists in the field of security are now 
aware of
the need to evaluate not only the quality features of any product, but also 
of
the need to predict any possible negative influence arising from its
implementation on the security of a corporate network.

This article looks at the results of research into wireless intrusion 
detection
systems from the point of view of the specialist in the field of 
applications
security. Design faults discovered are not discussed in the article as their
correction requires significant effort on the part of the manufacturer.

Web-style Wireless IDS attacks
WIDS architecture

A modern system of detecting wireless intrusion is a fairly complicated
solution based on two- or three-tier architecture - often based on Web
technologies.

WIDS architecture is based on sensors which collect, and sometimes
process, wireless traffic as part of the monitoring process. Sensors can be
based on standard operating systems or "specialised software and hardware
platforms" (in most cases Linux). As a rule, sensors are quite intelligent
devices which support TCP/IP and have sophisticated control interfaces.

The Sensors interact with the data collection component (server), and
transfer to it information on detected intrusions or intercepted packets. 
The
server processes information received, and performs the functions of
detecting intrusions and correlating security-related events. A standard
DBMS (database management system) is normally used to store
information. To manage the system and monitor events, a control console is
used in the form of a "fat" or "thin" client.

Thus, WIDS is a distributed system which is potentially vulnerable to
intrusions not only in a wireless area.

Sources of threats

It is possible to give the article a more formally scientific tone with the
formation of an "intruder model", i.e. to define basic anthropogenic sources
of threats. For WIDS these include external intruders interacting with the
system through radio ether, internal intruders who have access to a local
network, and operators who have certain limited opportunities to manipulate
system components.


Hacking through air gaps

The principal mechanisms by which external intruders impacts on the
wireless intrusion detection system are based on the creation of 802.11
frames, processing of which leads to non-standard situations. The
experience of wired intrusion detection systems [1], and also the packet
sniffers Ethereal/Wireshark, shows that the presence of vulnerabilities in

Web-style Wireless IDS attacks
"vivisectors" of complex network protocols is entirely normal. The state
machine of 802.11 link layer is fairly complicated, so as to confuse the
developers. Vulnerabilities in Kismet [2], coupled with recent publications

[3] on vulnerabilities in drivers of wireless clients, are compelling people 
to
consider the probable presence of such problems in WIDS sensors. However,
this has only a weak connection with the theme of the article.
The data received from a non-trusted source is saved in a database and
there is the probability of it not being processed correctly. And as a 
result
there is a possibility of an intruder carrying out SQL Injection-type 
attacks.
By adding to the packets fields of special symbols it is possible to 
terminate
the initial SQL query and add SQL operators to it. In practice, such an
intrusion can be carried out by creating fake access points or peer-to-peer
networks with SSID like:

';insert into ...

A fundamental, but surmountable restriction to the use of this type of
vulnerability is the SSID length (32 bytes).

At present, such vulnerability is processed as part of the policy of
responsible disclosure and will possibly be published at a later date.
However, the reader can verify the WIDS response to the crafted wireless
networks using DBMS tracking tools (SQL Profiler or similar), for example:

iwconfig ath0 mode master essid ';-- 

A further widely-accepted Web vulnerability characteristic of wireless
intrusion detection systems is Cross-Site Scripting. Information on a
detected intrusion appears in the control console, often Web browser-based.
Accordingly, an intruder can select as the SSID of the fake access point a
magical sequence of symbols:

">

And it launches a script in the browser of the operator or administrator
which can be controlled by the intruder. In such a case, 32 bytes is 
adequate
to specify external server as a source of the script. The results of such
intrusion may be many and varied - from the theft of authentication data
through to carrying out certain actions related to customising of the WIDS
setup - in place of the operator. Such vulnerabilities was detected in the
Web interface of the Airmagnet Enterprise server [4]. The conditions of the

Web-style Wireless IDS attacks
stored XSS arose when the wireless networks SSID appeared in the access
control lists Enterprise Server

https:///Amom/Amom.dll/BD

Where a "fat" client is used the situation can be complicated. For example,
the AirMagnet control console for displaying information about an intrusion
uses an embedded Internet Explorer object and inserts in the HTML template
SSID of access points (or the client) without screening. If the browser 
works
in the security zone Local Machine, the insertion of scripts may lead to
serious consequences. Further details about risks associated with use in
applications of the object Internet Explorer working in the security zone My
Computer can be found in [5] and [6].

In practice, all tested solutions are vulnerable to Cross-site Request 
Forgery
(CSRF) attacks. However, this vulnerability is so widespread that it was not
even considered worth mentioning.

Of course, implementation of these intrusions requires that the intruder has
information about the type of WIDS used, but this issue is fairly well
described in the publication [7].

Intrusions on a local network

An internal user has far more opportunities than his external intruder
counterpart. Since WIDS control interfaces for sensors and servers are fully
functional Web interfaces, it is highly probable that an intruder will be 
able
to find in these applications the entire range of vulnerabilities from Web
Application Consortium Threads Classification [8].

Examples include vulnerabilities [9], in Cisco WLSE and so on. In the sensor
control interface AirMagnet SmartEdge Sensor a persistent Cross-Site
Scripting vulnerability was detected in audit journals reviewing interface:

https:///AirMagnetSensor/AMSensor.dll/XH

 WebServer Log

In order to carry out an intrusion in this case, the name of the user 
entered
at the time of authentication is used. The non-persistent variant XSS is
present in 404-error pages:

http:// IP>/xss 

https:///xss

One further vector of intrusions which an internal intruder can use is
network interaction between system components, such as collection of data
from sensors, saving events in a DBMS, remote-control and browsing
events. Naturally, this traffic is sufficiently critical for vendors to deal 
with its
protection using such reliable protocols as SSL.

However, concern about convenience of users is compelling manufacturers
to use self-signed certificates rather than use a proper PKI-style 
verification
process. For example, the control console Airmagnet accepts practically any
certificate in the server response. This allows an intruder who has 
satisfied
the "man in the middle" conditions to decipher traffic (including user
passwords) transmitted between the control console and the server by using
generally accessible tools such as ettercap or Cain [10]. Below is an 
example
of traffic intercepted and deciphered.

[Client-side-data]
GET /AMom/AMom.dll/UA HTTP/1.1
Accept: */*
AMUser: admin 
AMBuild: 4694
User-Agent: AirMagnet
Host: 
Connection: Keep-Alive
Authorization: Basic YWRtaW46MTExMTEx

[Server-side-data]
HTTP/1.1 200 OK
Date: Mon, 20 Mar 2006 12:53:12 GMT
Server: Apache/2.0.52 (Win32) mod_ssl/2.0.52 OpenSSL/0.9.7a
Content-Length: 301
Keep-Alive: timeout=15
Connection: Keep-Alive
Content-Type: text/html

[Server-side-data]

3 2 AirMagnetSensor 111111 16777215 1

0

Copyright =BF 2006 Positive Technologies www.ptsecurity.com 

=0C
Web-style Wireless IDS attacks
111111111111111111111111111111111111111111111111111111111111
1111 1 admin111111 16777215 1 0
111111111111111111111111111111111111111111111111111111111111
1111 3 AirMagnetSensor2 111111 16777215 1 0
0 

Moreover, WIDS can work with active network equipment, for example
switches, using non-secure network protocols such as SNMPv1, which also
affords the intruder certain advantages.

Operator intrusions

In most WIDS the access control mechanism is in place. Users can have
authorisation to carry out only certain operations, for example only browse
events, or the range of their authorisation can be restricted by certain
groups of sensors (building, floor).

Where vulnerabilities exist in the control interface, this group of users 
has
the opportunity to increase its privileges within the scope of the intrusion
detection system or the entire network if the vulnerability is sufficiently
serious.

In the process of testing Highwall Enterprise Server and Highwall EndPoint
4.0.2.11045 many Cross-Site Scripting- and SQL Injection-type
vulnerabilities were detected. A user with the right to change system
parameters (for example names of the sensor WIDS or workstation on which
Highwall EndPoint is set up) can insert Javascript operators in the pages of
the server and transfer the authorisation data of a more privileged user or
perform actions on the WIDS device in that user's name.

The function of viewing information about system objects access points and
buildings contains an SQL Injection vulnerability, which allows the operator
to carry out SQL instructions on the DBMS server. Where an application
which uses the Microsoft SQL server has high privileges, the intruder has
many opportunities to realize attacks.

Conclusion

I would like to conclude by giving several minor recommendations for
specialists selecting or configuring a wireless intrusion detection system.

1. Check the system response to non-standard traffic in the wireless
network. Several examples of such traffic were given in the article. In
addition different fuzzers, for example [11] can be used.
2. Pay attention to the level of privileges used by the WIDS to work with
the DBMS. The consequences of intrusions could be very serious if a
superuser account is used.
3. When planning a network infrastructure for the WIDS, be aware of the
requirements for separation of networks. Transfer control traffic to a
separate segment/VLAN.
4. Switch off unused control protocols on remote sensor. The use of
telnet in 2006 can only be justified by constructing a honeypot.
5. Scan the network interfaces of the WIDS sensors and servers using a
vulnerabilities scanner which supports Web applications. I guarantee
that, in most cases, you will get a nasty shock. It is important that you
make a backup copy of the system. A scanner may inadvertently
obtain access to a remote controls and cause mayhem by pressing all
available buttons.
6. Pay serious attention to the management workstation. The author uses
the following approach, which is easily realised by using a proxy
server:
=07 the browser used for working in the corporate network does not
have access to Internet resources.
=07 the browser working with the Internet is restricted to use of
corporate resources, and works in a "sandbox".
7. It is also possible to block the execution of scripts in the security 
zone
My Computer [12] or to use Terminal Server for keeping client
applications separate.
8. Try to use the WIDS system as a critical business application and fulfil
the requirements formulated in the security policy for the given class
of product. In addition to a special review of the policy, it is a unique
opportunity to be with the IT specialists and users who carry out the
requirements of the policy every day.

References

[1] Vulnerabilities in Snort 2.4
http://www.security.nnov.ru/soft/6810.html?l=EN 

[2] Kevin Finisterre, 
http://www.security.nnov.ru/docs3012.html 

[3] Johnny , David Maynor 
www.blackhat.com/presentations/bh-usa-06/BH-US-06-Cache.pdf 

[4] AirMagnet Enterprise
http://www.airmagnet.com/products/enterprise.htm 

[5] 
http://www.securityfocus.com/bid/14385/references 

[6] SPI Dynamics, 
http://www.spidynamics.com/assets/documents/HackingFeeds.pdf 

[7] Joshua Wright, 
http://i.cmpnet.com/nc/1612/graphics/SessionContainment_file.pdf 

[8] Web Application Security Consortium, Threats Classification
http://www.webappsec.org/projects/threat/ 

[9] Cisco Security Advisory: Multiple Vulnerabilities in the WLSE Appliance
http://www.cisco.com/warp/public/707/cisco-sa-20060419-wlse.shtml 

[10] Cain & Abel
http://www.oxid.it/cain.html 

[11] Raw Wireless Tools Homepage
http://rfakeap.tuxfamily.org/ 

[12] How to strengthen the security settings for the Local Machine zone in
Internet Explorer
http://support.microsoft.com/kb/833633