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Securing a Wireless Network

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... encodings (one mandatory, two optional) that boost its speed. ... WEP relies on a secret key that is shared between a mobile station and an access point. ... – PowerPoint PPT presentation

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Title: Securing a Wireless Network


1
Securing a Wireless Network
2
Securing a Wireless Network
  • Wireless networks are rapidly becoming pervasive.
  • How many of you have web-enabled cell phones?
  • How many of you have networked PDAs and Pocket
    PCs?
  • How many of you have laptops with wireless
    network cards?
  • How many of you have wireless networks at work?
        at home?
  • How many of you use wireless networks when you
    are out and about?

3
Securing a Wireless Network
  • Of those of you who have wireless devices, how
    many of you
  • protect your wireless device with a password?
  • encrypt the data in your wireless device?
  • employ any type of security with your wireless
    device?
  • employ security with your wireless network?

4
Securing a Wireless Network
  • Wireless Technology
  • Security Vulnerabilities with Wireless Networks
  • Wireless Security Solutions
  • Precautions

5
Securing a Wireless Network
  • Most wireless networks today use the 802.11
    standard for communication. 802.11b became the
    standard wireless ethernet networking technology
    for both business and home in 2000. The IEEE
    802.11 Standard is an interoperability standard
    for wireless LAN devices, that identifies three
    major distribution systems for wireless data
    communication
  • Direct Sequence Spread Spectrum (DSSS) Radio
    Technology
  • Frequency Hopping Spread Spectrum (FHSS) Radio
    Technology
  • Infrared Technology

6
Independent Basic Service Set (IBSS) - computers
talk directly to each other
7
Basic Service Set (BSS) Network - all traffic
passes through a wireless access point
8
Extended Service Set (ESS) Network - traffic
passes through multiple wireless access points
9
IEEE 802.11b specification
  • wireless transmission of approximately 11 Mbps of
    raw data
  • indoor distances from several dozen to several
    hundred feet
  • outdoor distances of several to tens of miles
  • use of the 2.4 GHz band.
  • 802.11b appeared in commercial form in mid-1999.
  • Wireless Ethernet Compatibility Alliance (WECA)
    certifies equipment as conforming to the 802.11b
    standard, and allows compliant hardware to be
    stamped Wi-Fi compatible.
  • wireless NICs transmit in the range of 11, 5.5, 2
    and 1 Mbit/s at a frequency of 2.4 GHz.
  • 802.11b is a half duplex protocol

10
IEEE 802.11b specification
  • Multiple 802.11b access points can operate in the
    same overlapping area over different channels,
    which are subdivisions for the 2.4 GHz band.
    There are 14 channels, which are staggered at a
    few megahertz intervals, from 2.4000 to 2.4835
    GHz. Only channels 1, 6, and 11 have no overlap
    among them.
  • cards equipped with the Wired Equivalent Privacy
    (WEP) data encryption, based on the 64 bit RC4
    encryption algorithm as defined in the IEEE
    802.11b standard on wireless LANs. In addition,
    there are more expensive cards that are able to
    use 128 bit encryption. All your nodes must be at
    the same encryption level with the same key to
    operate.

11
IEEE 802.11b specification
  • Any network adapter coming within range of
    another 802.11b network adapter or access point
    can instantly connect and join the network unless
    WEP wireless encryption protocol is enabled.
    WEP is secure enough for most homes and business
    but dont think it cant be hacked. There are
    several flaws in WEP making it unusable for high
    security applications. At this point, it takes
    some serious hacking abilities to bust into a WEP
    enabled network so home users should not worry.
  • Full strength 802.11b signal will get you about
    3.5-4.5 Mbps without WEP enabled. With WEP
    enabled, expect 2.5-3.5 Mbps. As you put walls
    and distance between your wireless adapter and
    your access point, your speed will drop. Dont
    expect to put more than a few walls between you
    and your access point.

12
IEEE 802.11a specification
  • Within the last year, devices that comply with
    the 802.1a standard (54 Mbps over the 5 GHz band)
    have been released. 802.11a also has 12 channels
    (eight in the low part of the band and four in
    the upper) which do not overlap, allowing denser
    installations. 802.11a's range is apparently
    less, but it can often transmit at higher speeds
    at similar distances compared to 802.11b.
  • 802.11a devices use the same Wired Equivalent
    Privacy (WEP) security. Some vendors, such as
    Orinoco and Proxim, have included configurable
    (albeit non-standard) high-encryption
    capabilities into their access points to prevent
    simple WEP cracking.

13
IEEE 802.11g specification
  • 802.11g devices (54 Mbps over 2.4 GHz) will be
    released in mid-2003. 802.11g features backwards
    compatibility with 802.11b, and offers three
    additional encodings (one mandatory, two
    optional) that boost its speed.
  • Several related IEEE protocols address security,
    quality of service, and adaptive signal use
    (802.11e, h, and i, among others). 802.11i will
    offer additional security for 802.11. This
    standard will replace WEP and build on IEEE
    802.1X.
  • IEEE 802.1x is a standard for passing EAP over a
    wired or wireless LAN

14
Security Vulnerabilities
  • packet sniffing - war drivers higain antenna
  • War Driver Map of LA
  • Antenna on the Cheap (er, Chip) - Pringle's can
    antenna
  • Coffee Can Antenna
  • resource stealing - using a valid station's MAC
    address
  • traffic redirection - modifying ARP tables
  • rogue networks and station redirection network
    administrators also rely on manufacturers'
    default Service Set IDentifiers (SSIDs)The
    Gartner Group estimates that at least 20 percent
    of enterprises have rogue wireless LANs attached
    to their networks.
  • DoS (any radio source including 2.4 Ghz cordless
    phones)

15
Security Vulnerabilities
  • Wired Equivalent Privacy (WEP) algorithm used to
    protect wireless communication from
    eavesdropping. secondary function of WEP is to
    prevent unauthorized access to a wireless
    network.
  • WEP relies on a secret key that is shared between
    a mobile station and an access point. The secret
    key is used to encrypt packets before they are
    transmitted, and an integrity check is used to
    ensure that packets are not modified in transit.
    Most installations use a single key that is
    shared between all mobile stations and access
    points. More sophisticated key management
    techniques can be used to help defend from
    attacks.

16
Security Vulnerabilities
  • WEP uses the RC4 encryption algorithm, known as a
    stream cipher. A stream cipher expands a short
    key into infinite pseudo-random key stream. The
    sender XORs the key stream with the plaintext to
    produce ciphertext. The receiver has a copy of
    the same key, and uses it to generate identical
    key stream. XORing the key stream with the
    ciphertext yields the original plaintext.
  • If an attacker flips a bit in the ciphertext,
    then upon decryption, the corresponding bit in
    the plaintext will be flipped. Also, if an
    eavesdropper intercepts two ciphertexts encrypted
    with the same key stream, it is possible to
    obtain the XOR of the two plaintexts. Once one of
    the plaintexts becomes known, it is trivial to
    recover all of the others.

17
Security Solutions
  • Wired Equivalent Privacy (WEP) and WEP2
  • Media access control (MAC) addresses configuring
    access points to permit only particular MAC
    addresses onto the network. Easy to implement,
    but fairly easy to defeat.
  • IEEE 802.1X This standard, supported by Windows
    XP, defines a framework for MAC-level
    authentication. Susceptible to session-hijacking
    and man-in-the-middle attacks.
  • VPNs using a VPN to encrypt data on wireless
    networks. VPNs require a lot of management and
    client configuration.
  • User authentication
  • The Temporal Key Integrity Protocol (TKIP) IEEE
    802.11i

18
Security Solutions
  • Advanced Encryption Standard (AES) encryption
    IEEE 802.11i
  • "Key-hopping" technology that can change the
    encryption key as often as every few seconds.
  • EAP-TTLS (Extensible Authentication Protocol
    (EAP) - Tunneled Transport Layer Security)
  • Enhanced Security Network (ESN) - Extended
    Service Set with
  • enhanced authentication mechanism for both STAs
    and APs based on 802.11x
  • key management
  • dynamic, association-specific cryptographic keys
  • enhanced data encapsulation using AES

19
Security Solutions
  • Wireless Protocol Analyzers. They can
  • check for unknown MAC (Media Access Control)
    addresses and alert the network manager
  • log attempts to gain unauthorized access to the
    network
  • filter access attempts based on the type of
    network card
  • conduct site survey of traffic usage
  • find dead zones in the wireless network

20
Wireless Security Precautions
  • Change default names
  • Add passwords to all devices
  • Disable broadcasting on network hubs
  • Don't give the network a name that identifies
    your company
  • Move wireless hubs away from windows
  • Use the built-in encryption
  • Disable the features you don't use
  • Put a firewall between the wireless network and
    other company computers
  • Encrypt data
  • Regularly test wireless network security

21
Securing a Wireless Network
  • "What's happening with wireless networks is that
    it's no more or less secure than anything else.
    It's just that with a wireless LAN local area
    network you need a new page in the rule book.
    Security doesn't stop at the perimeter of the
    company building.
  • Geoff Davies, managing director of I-SEC, a
    specialist information security company,
    reprinted in Financial Times, July 1 2002
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