Wireless and Instant Messaging
Chapter 8
Learning Objectives
Understand security issues related to wireless data transfer
Understand the 802.11x standards Understand Wireless Application Protocol
(WAP) and how it works Understand Wireless Transport Layer
Security (WTLS) protocol and how it works
continued…
Learning Objectives
Understand Wired Equivalent Privacy (WEP) and how it works
Conduct a wireless site survey Understand instant messaging
802.11
IEEE group responsible for defining interface between wireless clients and their network access points in wireless LANs
First standard finalized in 1997 defined three types of transmission at Physical layer
Diffused infrared - based on infrared transmissions Direct sequence spread spectrum (DSSS) - radio-
based Frequency hopping spread spectrum (FHSS) - radio-
based
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802.11
Established WEP as optional security protocol
Specified use of 2.4 GHz industrial, scientific, and medical (ISM) radio band
Mandated 1 Mbps data transfer rate and optional 2 Mbps data transfer rate
Most prominent working groups: 802.11b, 802.11a, 802.11i, and 802.11g
802.11a
“High-Speed Physical Layer in the 5 GHz Band”
Sets specifications for wireless data transmission of up to 54 Mbps in the 5 GHz band
Uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS
Approved in 1999
802.11b
“Higher-Speed Layer Extension in the 2.4 GHz Band”
Establishes specifications for data transmission that provides 11 Mbps transmission (with fallback to 5.5, 2, and 1 Mbps) at 2.4 GHz band
Sometimes referred to as “Wi-Fi” when associated with WECA certified devices
Uses only DSSS Approved in 1999
802.11c
Worked to establish MAC bridging functionality for 802.11 to operate in other countries
Folded into 802.1D standard for MAC bridging
802.11d
Responsible for determining requirements necessary for 802.11 to operate in other countries
Continuing
802.11e
Responsible for creating a standard that will add multimedia and quality of service (QoS) capabilities to wireless MAC layer and therefore guarantee specified data transmission rates and error percentages
Proposal in draft form
802.11f
Responsible for creating a standard that will allow for better roaming between multivendor access points and distribution systems
Ongoing
802.11g
Responsible for providing raw data throughput over wireless networks at a throughput rate of 22 Mbps or more
Draft created in January 2002; final approval expected in late 2002 or early 2003
802.11h
Responsible for providing a way to allow for European implementation requests regarding the 5 GHz band
Requirements Limits PC card from emitting more radio signal than
needed Allows devices to listen to radio wave activity before
picking a channel on which to broadcast Ongoing; not yet approved
802.11i
Responsible for fixing security flaws in WEP and 802.1x
Hopes to eliminate WEP altogether and replace it with Temporal Key Integrity Protocol (TKIP), which would require replacement of keys within a certain amount of time
Ongoing; not yet approved
802.11j
Worked to create a global standard in the 5 GHz band by making high-performance LAN (HiperLAN) and 802.11a interoperable
Disbanded after efforts in this area were mostly successful
Wireless Application Protocol (WAP)
Open, global specification created by the WAP Forum
Designed to deliver information and services to users of handheld digital devices
Compatible with most wireless networks Can be built on any operating system
WAP-Enabled Devices
WAP-Enabled Devices
How WAP 1x Works
WAP 1.x Stack Set of protocols created by the WAP Forum
that alters the OSI model Five layers lie within the top four (of seven)
layers of the OSI model Leaner than the OSI model
Each WAP protocol makes data transactions as compressed as possible and allows for more dropped packets than OSI model
WAP 1.x Stack Compared to OSI/Web Stack
Differences Between Wireless and Wired Data Transfer
WAP 1.x stack protocols require that data communications between clients (wireless devices) and servers pass through a WAP gateway
Network architectural structures
WAP versus Wired Network
The WAP 2.0 Stack
Eliminates use of WTLS; relies on a lighter version of TLS – the same protocol used on the common Internet stack – which allows end-to-end security and avoids any WAP gaps
Replaces all other layers of WAP 1.x by standard Internet layers
Still supports the WAP 1.x stack in order to facilitate legacy devices and systems
Additional WAP 2.0 Features
WAP Push User agent profile Wireless Telephony Application Extended Functionality Interface (EFI) Multimedia Messaging Service (MMS)
Wireless Transport Layer Security (WTLS) Protocol
Provides authentication, data encryption, and privacy for WAP 1.x users
Three classes of authentication Class 1
Anonymous; does not allow either the client or the gateway to authenticate each other
Class 2 Only allows the client to authenticate the gateway
Class 3 Allows both the client and the gateway to authenticate each
other
WTLS Protocol: Steps of Class 2 Authentication
1. WAP device sends request for authentication
2. Gateway responds, then sends a copy of its certificate – which contains gateway’s public key – to the WAP device
3. WAP device receives the certificate and public key and generates a unique random value
4. WAP gateway receives encrypted value and uses its own private key to decrypt it
WTLS Security Concerns
Security threats posed by WAP gap Unsafe use of service set identifiers
(SSIDs)
Wired Equivalent Privacy (WEP)
Optional security protocol for wireless local area networks defined in the 802.11b standard
Designed to provide same level of security as a wired LAN
Not considered adequate security without also implementing a separate authentication process and providing for external key management
Wireless LAN (WLAN)
Connects clients to network resources using radio signals to pass data through the ether
Employs wireless access points (AP) Connected to the wired LAN Act as radio broadcast stations that transmit
data to clients equipped with wireless network interface cards (NICs)
How a WLAN Works
APs
NICs
How WEP Works
Uses a symmetric key (shared key) to authenticate wireless devices (not wireless device users) and to guarantee integrity of data by encrypting transmissions
Each of the APs and clients need to share the same key
Client sends a request to the AP asking for permission to access the wired network
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How WEP Works
If WEP has not been enabled (default), the AP allows the request to pass
If WEP has been enabled, client begins a challenge-and-response authentication process
WEP’s Weaknesses
Problems related to the initialization vector (IV) that it uses to encrypt data and ensure its integrity Can be picked up by hackers Is reused on a regular basis
Problems with how it handles keys
Other WLAN Security Loopholes
War driving Unauthorized users can attach themselves to
WLANs and use their resources, set up their own access points and jam the network
WEP authenticates clients, not users Wireless network administrators and users must
be educated about inherent insecurity of wireless systems and the need for care
Conducting a Wireless Site Survey
1. Conduct a needs assessment of network users
2. Obtain a copy of the site’s blueprint
3. Do a walk-through of the site
4. Identify possible access point locations
5. Verify access point locations
6. Document findings
Instant Messaging (IM)
AOL Instant Messenger (AIM) MSN Messenger Yahoo! Messenger ICQ Internet Relay Chat (IRC)
Definition of IM
Uses a real-time communication model Allows users to keep track of online status
and availability of other users who are also using IM applications
Can be used on both wired and wireless devices
Easy and fast
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Definition of IM
Operates in two models: Peer-to-peer model
May cause client to expose sensitive information Peer-to-network model
Risk of network outage and DoS attacks making IM communication unavailable
Problems Facing IM
Lack of default encryption enables packet sniffing
Social engineering overcomes even encryption
Technical Issues Surrounding IM
Files transfers Application sharing
Legal Issues Surrounding IM
Possible threat of litigation or criminal indictment should the wrong message be sent or overheard by the wrong person
Currently immune to most corporate efforts to control it
Must be monitored in real time
Blocking IM
Install a firewall to block ports that IM products use; IM will be unavailable to all employees
Limited blocking not currently possible
Cellular Phone Simple Messaging Service (SMS)
Messages are typed and sent immediately Problems
Tracking inappropriate messages Risk of having messages sniffed
Chapter Summary
Efforts of IEEE, specifically 802.11x standards, to standardize wireless security
Security issues related to dominant wireless protocols WAP
Connects mobile telephones, PDAs, pocket computers, and other mobile devices to the Internet
WEP Used in WLANs
continued…
Chapter Summary
WTLS protocol Conducting a site survey in advance of
building a WLAN Security threats related to using (IM)