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

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 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 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 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)