Title: Lesson 12 Wireless and Instant Messaging
1Lesson 12- Wireless and Instant Messaging
2Overview
- What is Wireless? The term wireless refers to
telecommunication technology, in which radio
waves, infrared waves and microwaves, instead of
cables or wires, are used to carry a signal to
connect communication devices. - These devices include pagers, cell phones,
portable PCs, computer networks, location
devices, satellite systems and handheld digital
assistants. - Wireless networking is the transmission of data
using a physical topology, not direct physical
links.
3Wireless Data Networks
50 Mbps
802.11 is WiFi WAP is small handhelds
Spread Spectrum Wireless LANs
10 Mbps
Infrared Wireless LANs
2 Mbps
1 Mbps
Data Rates
56 Kbps
19.6 Kbps
Narrow Band Wireless LANs
Satellite
9.6 Kbps
Local
Wide
Coverage Area
4Wireless Landscape
WiMAX as a last-mile alternative for remote areas
not currently served by DSL or cable
5Wireless Technologies
WAN (Wide Area Network)
MAN (Metropolitan Area Network)
LAN (Local Area Network)
PAN (Personal Area Network)
6Bluetooth
- Uses devices with small radio transceivers,
called radio modules, built onto microprocessor
chips - Special software, called a link manager,
identifies other Bluetooth devices, creates links
with them, and sends and receives data - Transmits at up to 1 Mbps over a distance of 33
feet and is not impeded by physical barriers - Bluetooth products created by over 1500 computer,
telephone, and peripheral vendors
7PAN
- Two or more Bluetooth devices that send and
receive personal area network (PAN - Many challenges face Bluetooth
- Cost chip prices have increased
- Limited support
- Shortcomings in protocol itself no handoff
between piconet and security not optimal - Positioning in marketplace
- Conflicts with other devices in radio spectrum
Bluetooth was named after the 10th century Danish
King Harold Bluetooth, who was responsible for
unifying Scandinavia
8Background
- Wireless and instant messaging are two topics of
concern to computer and network security
professionals. - Wireless systems are vulnerable since data flows
over the unsecured air waves - There is no control over the physical layer of
the traffic. - If an attacker can get close enough to the
signal's source, he can listen and capture all
the packets for examination. - Attackers may modify the traffic being sent, or
send their own traffic to disrupt the system. - Instant messaging sends unencrypted traffic to
and from the Internet-based messaging servers. - IM is an uncontrolled file transfer.
9Wireless
- Two of the most common point-to-multipoint
systems are - Wireless Application Protocol (WAP)
- Designed to support all the services of the new
PDA and wireless e-mail devices including cell
phone and pager capabilities - IEEE 802.11
- The 802.11 protocol has been standardized by the
IEEE for wireless local area networks..
10CIA and WTLS
- Wireless Transport Layer Security (WTLS) was
developed to avoid broadcasting clear data. - It is a lightweight encryption protocol derived
from the current Transport Layer Security (TLS)
protocol in use across the Internet. - WTLS Authentication can be performed in several
ways, including digital certificates, tokens, or
simple passwords. - Designed to meet fundamental requirements for
security confidentiality, integrity, and
authentication. - Confidentiality - Wireless affords no control
over the physical medium - Only authorized users can read sent and received
packets - Encryption is the best way to ensure
confidentiality Integrity - Integrity is accomplished by indicating that the
information has not been modified. - Authentication - Both sender and receiver must
authenticate, uses WTLS.
11Wireless Transport Layer Security (WTLS) Protocol
- WTLS uses a modified version of the TLS protocol,
formerly known as SSL. - WTLS uses modern cryptographic algorithms and in
common with TLS allows negotiation of
cryptographic suites between client and server. - Algorithms - An incomplete list
- Key Exchange and Signature
- RSA
- Elliptic Curve Cryptography (ECC)
- Diffie Hellman
- Symmetric Encryption
- DES
- Triple DES
- RC5
- IDEA
- Message Digest
- MD5
- SHA1
12WTLS Protocol Authentication
- WAP device sends request for authentication
- Gateway responds, then sends a copy of its
certificate which contains gateways public key
to the WAP device - WAP device receives the certificate and public
key and generates a unique random value - WAP gateway receives encrypted value and uses its
own private key to decrypt it
13Security Issues with WTLS
- WTLS protocol is designed around more capable
servers than devices, which have small amounts of
memory and limited processor capacity. - Encryption is prohibited because of low memory or
CPU capabilities - Authentication is optional and is done with
digital certificates. - WAP GAP - If an attacker were to compromise the
gateway, they would be able to access all of the
secure communications traversing the network
juncture - WTLS uses weaker keys
- WLAN Service set identifiers (SSIDs - later)
- There are known security vulnerabilities in the
implementation of WTLS, including - Chosen plaintext attack
- PKCS 1 attack
- Alert message truncation attack
14WTLS Chosen Plain Text
- The chosen plaintext attack works on the
principle of predictable Initialization Vectors
(IVs). - By the nature of the transport medium that it is
using, WAP, WTLS needs to support unreliable
transport. - This forces the IV to be based upon data already
known to the client, and WTLS uses a linear IV
computation. - The IV is based on the sequence number of the
packet and several packets are sent unencrypted,
severely decreasing entropy, which reduces
confidentiality.
15WTLS, PKCS and AMT
- PKCS used with RSA encryption gives a standard
for formatting the padding used to generate a
correctly formatted block size. - When the client receives the block, it will reply
to the sender as to the validity of the block. - In the PKCS 1 attack, an attacker attempts to
send multiple guesses at the padding to force a
padding error. - Alert messages in WTLS are sometimes sent in
plaintext and are not authenticated. - This allows an attacker to overwrite an encrypted
packet from the actual sender with a plaintext
alert message. - It would lead to possible disruption of the
connection through a truncation attack.
16WAP GAP security issue
- There is concern over the so-called WAP GAP.
- Confidentiality of information is vulnerable
where two different networks meet. - WTLS acts as the security protocol for the WAP
network, and TLS is the standard for the
Internet, and the WAP gateway translates one
encryption standard to the other in plaintext. - A WAP gateway is an especially appealing target,
as plaintext messages are processed through it
from all wireless devices, not just a single
user.
17IEEE 802.11 Standards Activities
- 802.11 refers to a family of specifications
developed by the IEEE for wireless LAN
technology. - 802.11a 5GHz, 54Mbps
- 802.11b 2.4GHz, 11Mbps
- 802.11d Multiple regulatory domains
- 802.11e Quality of Service (QoS)
- 802.11f Inter-Access Point Protocol (IAPP)
- 802.11g 2.4GHz, 54Mbps
- 802.11h Dynamic Frequency Selection (DFS) and
Transmit Power Control (TPC) - 802.11i Security
- 802.11j Japan 5GHz Channels (4.9-5.1 GHz)
- 802.11k Measurement
18802.11
Electromagnetic Spectrum any particular spot on
the spectrum is defined by its wave length and
frequency.
- IEEE standard - introduced in 1990
- Defined cable-free local area network with either
fixed or mobile locations that transmit at either
1 or 2 Mbps which was insufficient for most
network applications - A new standard was developed for sending
packetsized data traffic over radio waves in the
unlicensed 2.4 Ghz band. - Unlicensed, means it does not have to be
certified by the FCC, and devices could possible
share the bandwidth with other devices such as
cordless phones, baby monitors etc.
19Physical Layer OSI Model
- Defines how bits and bytes are transferred to and
from the physical medium, in the case, radio
waves of the electromagnetic spectrum. - If the device shares same physical layer (radio
frequency) implementations, they can communicate.
802.11b and 802.11g share the same frequency
20Three Wireless Technologies
802.11b
802.11g
802.11a
Frequency Band
2.4 GHz
5 GHz
2.4 GHz
Worldwide
US/AP
Worldwide
Availability
MaximumData rate
11 Mbps
54 Mbps
54 Mbps
Cordless Phones Microwave Ovens Wireless Video
Bluetooth Devices
Cordless Phones Microwave Ovens Wireless Video
Bluetooth Devices
Other Services (Interference)
HyperLAN Devices
The Laws of Radio Dynamics Higher Data Rates
Shorter Transmission RangeHigher Power
Output Increased Range, but Lower Battery
LifeHigher Frequency Radios Higher Data
Rates Shorter Ranges
21Wi-Fi
- Wi-Fi Alliance
- Wireless Fidelity Alliance
- 170 members
- Over 350 products certified
- Wi-Fis Mission
- Certify interoperability of WLAN products
(802.11) - Wi-Fi is the stamp of approval on all tested
products - Promote Wi-Fi as the global standard
22802.11 Authentication and Association
- The 802.11 standard includes rudimentary
authentication and confidentiality controls. - Authentication is handled in its most basic form
by the 802.11 access point (AP). - It forces the clients to perform a handshake when
attempting to associate to the AP. Association
is the process needed before the AP will allow
the client to talk across the AP to the network. - Association occurs only if the client has all the
correct parameters needed such as the service set
identifier (SSID) in the handshake.
23802.11 Access Security
- Access to wired ethernet segments is protected by
physical security measures but wireless will
broadcast beyond physical network - Attack is easy with a single wireless access card
costing less than 50 which can give access to
any unsecured AP within 300 feet - An attacker can probe and log packets without
giving any indication that an attempted intrusion
is taking place. - The attempted association is recorded only by the
MAC address of the wireless NIC associated to it.
- Most APs do not alert when users associate to it.
24Wireless LAN Security - War Driving
War Driving
Hacking into WEP
War driving (drive-by hacking or LAN-jacking) is
a play on war dialing. War dialing, in turn,
comes from the 1983 movie War Games, now a
classic in computer cracking circles.
Literally, war driving is using a laptops to
pick up unsecured wireless networks for anonymous
and free high-speed Internet access, akin to
stealing long-distance phone service.
25War Chalking
- Welcome to Warchalking! Warchalking is the
practice of marking a series of symbols on
sidewalks and walls to indicate nearby wireless
access. That way, other computer users can pop
open their laptops and connect to the Internet
wirelessly. It was inspired by the practice of
hobos during the Great Depression to use chalk
marks to indicate which homes were friendly.
26War Flying
- War flying uses airplanes to find the wireless
access points. The obvious advantage is the extra
height provides an unobstructed line. - Some people think war driving is illegal.
Actually accessing someone's network is illegal,
but detecting the network is not. You can think
of war driving as walking up to a house, and
checking to see if the door is unlocked. If you
find an unlocked door, you write down the address
and move to the next house. It becomes illegal
when you open the door and walk in, which is
similar to accessing the Internet through a AP
without the owner's permission.
27Using a Sniffer
- Specialized sniffer tools have emerged recently,
with a single objective, to crack WEP keys. - A sniffer and a wireless network card are a
powerful attack tool. - A shared media wireless network exposes all
packets to interception and logging. - They work by exploiting weak IV in the encryption
algorithm. - To exploit this weakness, you need a certain
number of ciphertext packets. Once you have
captured enough packets, the program can decipher
the encryption key being used very quickly. - Popular wireless sniffers are Ethereal,
WildPackets, AiroPeek and Sniffer Pro 4.0.
28NetStumbler
- The most widely used of these programs is called
Netstumbler by Marius Milner. - It listens for access point beacon frames in a
range and logs all available information about
the access point for later analysis. - If the computer has a GPS unit attached to it,
the program also logs the coordinates of the
access point. - This information can be used to return to the
access point, or to plot maps of access points in
a city. - This is a Windows-based application, but there
are programs that work on the same principle for
Mac, BSD, Linux, and other operating systems.
29Netstumbler Screen
30Sniffer Pro 4.0 Screen
31802.11 Authentication Tools
- SSID - service set identifier
- The SSID is a unique 32-character identifier
attached to the header of the packet. - It functions as a group identifier.
- The SSID is sent in plaintext.
- Some operating systems display a list of SSIDs
active in the area. - This weakness is magnified by the default setting
of most access points (linksys APs use linksys),
to transmit beacon frames. - The purpose of beacon frame is to announce the
presence and capabilities of wireless network so
that WLAN cards can associate.
32WEP
- 802.11 protects confidentiality with Wired
Equivalent Privacy (WEP), a key. - It is based upon a key shared by the AP and all
the clients using the AP. - WEP uses the RC4 stream cipher to encrypt data to
authenticate wireless devices (not wireless
device users) - The plaintext IV (initialization vector) is the
weaknesses in WEP - The total keyspace is approximately 16 million
keys. - Once the key is repeated, the attacker has two
ciphertexts encrypted with the same key stream. - The attacker may examine the ciphertext and
retrieve the key. - The weakness of the WEP protocol is that the IV
problem exists regardless of key length (24
bits).
- WEP is easily attacked
- How to crack WEP
33WPA
- Wi-Fi Protected Access (WPA) were created in
response to several serious weaknesses in Wired
Equivalent Privacy (WEP). - WPA implements the majority of the IEEE 802.11i
standard, and was intended as an intermediate
measure to take the place of WEP while 802.11i
was prepared. - WPA is designed to work with all wireless network
interface cards, but not necessarily with first
generation wireless access points. - WPA2 implements the full standard, but will not
work with some older network cards. - WPA is designed for use with an 802.1X
authentication server - WPA uses Temporal Key Integrity Protocol (TKIP)
and was meant to fix WEP problems. - TKIP uses a shared secret combined with the
card's MAC address to generate a new key. This is
then mixed with the initialization vector to make
per-packet keys that encrypt a single packet
using the same RC4 cipher that traditional WEP
uses. - The other advantage of WPA is that it can be
retrofitted to the current hardware with only a
software change, unlike AES and 802.1X.
34802.11i Standard
- Or, how do we get from here to there 802.11i? The
final IEEE security standard thats expected next
year with a robust set of security improvements.
. - Currently, all 802.11a, b, and g devices support
WEP (Wired Equivalent Privacy) encryption which
has had flaws and exploits well documented. - On the road to 802.11i, the Wi-Fi Alliance has
required WPA (Wi-Fi Protected Access), which
fixes all of WEPs problems, is a subset of
802.11i, and which allows full backwards
compatibility for most 802.11a and b devices made
before 2003. - 802.11i manages the encryption part but needs
802.1x to provide authentication, and the use of
AES as the encryption protocol.
35802.1x Standard
- The use of IEEE 802.1X authenticates and
dynamically varies encryption keys. - 802.1X ties a protocol called EAP (Extensible
Authentication Protocol) to both the wired and
wireless LAN media and supports multiple
authentication methods, such as token cards,
Kerberos, one-time passwords, certificates, and
public key authentication. IETF's RFC 2284. - It fits into existing authentication systems such
as RADIUS and LDAP. - It allows 802.1X to interoperate well with other
systems such as VPNs and dial-up RAS. - There are four common ways of implementing
802.1X - EAP-TLS support PKI in x.509 and active
directory - EAP-TTLS - EAPTunneled TLS Protocol
- EAP-MD5 - uses the MD5 encryption protocol to
hash a user's username and password - EAPCisco Wireless or LEAP - requiring two-way
authentication, AP authenticates to the client
and vice versa.
36WLAN Security Hierarchy
Enhanced Security
802.1x, TKIP/WPA Encryption, Mutual
Authentication, Scalable Key Mgmt., etc.
Basic Security
Open Access
40-bit or 128-bitStatic WEP Encryption
No Encryption, Basic Authentication
Home Use
Public Hotspots
Business
VirtualPrivateNetwork (VPN)
Business Traveler, Telecommuter
Remote Access
37Authentication Types Summary
- Open Authentication to the Access Point with WEP,
doesnt rely on RADIUS/TACACS server - Shared Key Authentication to the Access Point
WEP - EAP Authentication to the Network Combo EAP and
RADIUS/TACACS - MAC Address Authentication to the Network MACs
can be spoofed, but better than nothing - Combining MAC-Based, EAP, and Open Authentication
- Using CCKM for Authenticated Clients allows
Roaming - Using WPA Key Management
38Instant Messaging (IM)
- IM - Uses a real-time communication model
- The programs had to appeal to a wide variety of
users, so ease of use was paramount, and security
was not a priority. - Can be used on both wired and wireless devices
- The program is now being used not only for
personal chatting on the Internet, but also for
legitimate business use. - Easy and fast
- Instant messages - Send notes back and forth with
a friend who is online - Chat - Create your own custom chat room with
friends or co-workers - Web links - Share links to your favorite Web
sites - Images - Look at an image stored on your friend's
computer - Sounds - Play sounds for your friends
- Files - Share files by sending them directly to
your friends - Talk - Use the Internet instead of a phone to
actually talk with friends - Streaming content - Real-time or near-real-time
stock quotes and news
39IM
- User Base
- AIM 53 million active users (Nielsen//NetRatings,
August 2005), 195 million total (January 2003). - Skype 45 million total (September 2005).
- MSN Messenger 29 million active
(Nielsen//NetRatings, August 2005), 155 million
total (April 2005). - Yahoo Messenger 21 million active (September
2005). - Jabber 13.5 million total (Osterman Research
August 2005). - QQ 10 million active, 400 million total users
(Tencent Q1 results 2005). - Gadu-Gadu 3.6 million total (January 2005).
- ICQ 1.8 million active (September 2005), 140
million total (June 2003).
40Issues
- The nature of this type of communication opens
several holes in a system's security. - When attached to a server, it broadcasts the IP
address of the originating client. - Sends File Attachments
- Without an IM server, plain text messages go
directly to the internet (no encryption). - Rogue Applications - typically installed by the
end user - If server is not available on the default ports,
some IM applications begin to scan all ports
looking for one that is allowed out of the
firewall. - IM applications work only in a networked
environment and, therefore, are forced to accept
traffic as well as send it. - Social Engineering Overcomes Even Encryption. An
IM message can be sent to anyone. - While application sharing is great especially
for conferencing and remote control for helpdesk
purposes, if security is breached, your machine
may be controlled by an unknown party
41Issues
- Legal Issues Surrounding IM
- Basically, students should realize that if a
corporation allows IM, all bets are off regarding
the legal implications. - E-mail is much easier to control and has had
years of management review to make policies - E-mail provides a built-in logging capability
whereas IM messages are gone once they scroll off
the screen (if logging is not enabled). - Therefore, you could communicate with someone
with your logging turned off and they could be
logging the transaction. This puts you in a
legal disadvantage were your conversation to be
used in a legal proceeding.
42What to do?
- Use a local server.
- Keeping messages within the perimeter of the
organization goes a long way to ensuring that
confidential information does not get out. - Blocking IM
- block all IM and then monitor the network to see
if anyone has found a way around it or a new IM
is in use. - Policies
- Unfortunately, employees may make a convincing
case that IM is useful then the best that can
be done is make strong policies and limit IM
clients to one or two vendors so you can maximize
control. - Newer client programs, such as Trillian, can
encrypt the chat messages - While this does not help with file sharing
problems, it provides confidentiality if both
clients are using the program - Virus Scanner - to protect the method of file
exchange