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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
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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 continued…
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
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
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
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 • WAP device sends request for authentication • Gateway responds, then sends a copy of its certificate – which contains gateway’s 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
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 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 continued…
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 • Conduct a needs assessment of network users • Obtain a copy of the site’s blueprint • Do a walk-through of the site • Identify possible access point locations • Verify access point locations • 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 continued…
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)