wireless networking chapter three WAN.pdf

SECURITY OF WIRELESS LOCAL AREA
NETWORKS
CHAPTER 3

• Security usually refers to ensuring that users can
– perform only the tasks that they are authorized to do
– Access only the information that they are authorized to have.
– Security of Network, computer and information
• Information Security:
– Information security refers to the processes and methodologies which are designed
and implemented to protect print, electronic, or any other form of confidential,
private and sensitive information or data from unauthorized access, use, misuse,
disclosure, destruction, modification, or disruption.
– Wikipedia says, "Information security means protecting information and
information systems from unauthorized access, use, disclosure, disruption,
modification, or destruction.
• Network security
– Network security consists of the provisions and policies adopted to prevent and
monitor unauthorized access, misuse, modification, or denial of a computer network
and network-accessible resources.
– Network security involves the authorization of access to data in a network controlled
by the network administrator.
• Users choose or are assigned an ID and password or other authenticating
information that allows them access to information and programs within their
Introduction

• Computer security
– Computer security is Information security as applied to computer
and networks.
– The field covers all the processes and mechanisms by which
computer-based equipment, information and services are protected
from unauthorized access, change or destruction.
– Computer security refers to the security of computers against
intruders (e.g., hackers) and malicious software (e.g., viruses)
• Computer to be secured is attached to a network and the bulk of
the threats arise from the network.
• The goals of security are
– To maintain integrity:- protected from unauthorized change
– To protect confidentiality:- hidden from unauthorized access
– To ensure availability:- available to an authorized entity when it is
needed

Cont’d
Introduction and Terminology
• Cryptology: Cryptology is the science concerned with data communication and storage
in secure and secret form
• It is applied in implementing the Computer Security.
• cryptography deals with designing the secret codes and ciphers whereas the science of
cryptanalysis deals with "breaking" and reading secret codes and ciphers.
• Code: A code is simply an unvarying rule for replacing a piece of information (e.g.,
letter, word, or phrase) with another object, but not necessarily of the same sort, e.g.
ASCII.
• Ciphers: Ciphers, as in the case of codes, also replace a piece of information (an
element of the plaintext that may consist of a letter, word, or string of symbols) with
another object.
• Plaintext: The source information, written in incomprehensible binary stream of 1s and
0s is referred to as the plaintext

Cont’d
Introduction and Terminology
• Secret key: The secret information known only to the transmitter and the receiver
which is used to secure the PLAINTEXT.
• Encryption: The transformation of the plaintext under the control of the key into a
cipher (also called ciphertext) is referred to as encryption.
• Decryption: The inverse operation, by which a legitimate receiver recovers the
concealed information from the cipher using the key, is known as decryption
• Ciphertext: The encrypted form of the PLAINTEXT is known as CYPHERTEXT.
• MONOALPHABETIC SUBSTITUTION : A method of encryption where a letter in the
plaintext is always replaced by the same letter in the ciphertext.
• POLYALPHABETIC SUBSTITUTION: A method of encryption where a letter in the
plaintext is not always replaced by the same letter in the ciphertext.

I*
Security Techniques:
• Two techniques are prevalent today:
i. Cryptography:- concealing the content of a message by enciphering
ii. Steganography:- means concealing the message itself by covering it
with something else.
• a single secret key is used for both encryption and decryption.
• the sender puts a message in a box and locks the box using a shared key; the
receiver unlocks the box with the same key and takes out the message.
• Common symmetric key encryption algorithms include DES (the Data
Encryption Standard) and AES (the Advanced Encryption Standard).
• Common asymmetric key encryption algorithms include RSA algorithm
• The most popular hash functions are MD5 (Message Digest 5), which uses
128 bits and SHA1 (Secure Hash Algorithm 1), which uses 160 bits.
• Digital signature: This is a means by which the sender can electronically
sign the data and the receiver can electronically verify the signature.

Cont’d
Security Attacks:
• The three goals of security – confidentiality, integrity, and availability – can be
threatened by security attacks.
• Attacks threatening Confidentiality: In general, two types of attacks threaten the
confidentiality of information:
• Snooping:- refers to unauthorized access to or interception of data.
• traffic analysis:- An unauthorized entity can obtain some other type information
by monitoring online traffic.
• Attacks threatening Integrity: The integrity of data can be threatened by
several kinds of attacks:
 Modification : After intercepting or accessing information, the attacker modifies the
information to make it beneficial to himself.
 Replaying: The attacker obtains a copy of a message sent by the user and later tries to
replay it.
• Attacks threatening Availability: We mention only one attack threatening availability:
denial of service
• Denial of service: It is a common attack, which may slow down or totally interrupt
the service of a system.

Cont’d
Security Attacks:
• Passive vs. Active attacks: The attacks can be categorized into two groups:
1. Passive and
2. Active
• Passive Attacks: In a passive attack, the attacker’s goal is just to obtain
information. In this case, the attacker does not modify data or harm the
system
• It is difficult to detect this type of attack until the sender or receiver finds out about
the leaking of confidential information
• Active Attacks: An active attack may change the data and harm the system.
• Attacks that threatens the integrity and availability are active attacks .
• Active attacks are normally easier to detect than to prevent, because an attacker
can launch them in a variety of ways.

Cont’d
Common Security Threats:
Compromised-key attack
Network Denial-of-Service Attack
Eavesdropping
Identity Spoofing (IP Address Spoofing)
Man-in-the-Middle Attack
RTP (Real-time Transport Protocol) Replay Attack
SPIM (Spam over Instant Messaging)
Viruses and Worms

Cont’d
Common Security Threats
• Compromised-key attack: The attacker uses the key to decrypt encrypted data
without the knowledge of the sender of the data.
• Network Denial-of-Service Attack: The denial-of-service attack occurs when
the attacker prevents normal network use and function by valid users.
• Eavesdropping: Eavesdropping can occur when an attacker gains access to the
data path in a network and has the ability to monitor and read the traffic. This
is also called sniffing or snooping. If the traffic is in plain text, the attacker is
able to read the traffic when the attacker gains access to the path.
• Identity Spoofing (IP Address Spoofing): Spoofing occurs when the attacker
determines and uses an IP address of a network, computer, or network
component when not authorized to do so.

Cont’d
Common Security Threats
• Man-in-the-Middle Attack: A man-in-the-middle attack occurs when an
attacker reroutes communication between two users through the attacker's
computer without the knowledge of the two communicating users.
• This can happen if an attacker can modify Active Directory to add his or her server
as a trusted server or modify DNS to get clients to connect through the attacker
on their way to the server.
• RTP (Real-time Transport Protocol) Replay Attack: A replay attack occurs when
a valid media transmission between two parties is intercepted and
retransmitted for malicious purposes.
• SPIM (Spam over Instant Messaging): SPIM is unsolicited commercial instant
messages, or presence subscription requests.
• Viruses and Worms: A virus is a unit of code whose purpose is to reproduce
additional, similar code units. To work, a virus needs a host, such as a file, e-
mail, or program.

Introduction
target
Denial of Service (DoS): attackers make resources (server,
bandwidth) unavailable to legitimate traffic by
overwhelming resource with bogus traffic
1. select target
2. break into hosts around the
network (see botnet)
3. send packets to target from
compromised hosts
Bad guys: attack server, network infrastructure
1-12

Introduction
Bad guys can sniff packets
packet “sniffing”:
– broadcast media (shared ethernet, wireless)
– promiscuous network interface reads/records all packets
(e.g., including passwords!) passing by
A
B
C
src:B dest:A payload
 wireshark software used for end-of-chapter labs is a (free) packet-sniffer
1-13

Introduction
Bad guys can use fake addresses
IP spoofing: send packet with false source
address
A
B
C
src:B dest:A payload
1-14
… lots more on security (throughout, Chapter 8)

Access - Rogue AP Attack
• Most clients will associate to the access point with the strongest signal. If an
unauthorized AP, which is generally a rogue AP, has a strong signal, clients will
associate to the rogue AP.
• The rogue AP will have access to the network traffic of all associated clients.
• The rogue AP can also use ARP and IP spoofing to trick clients into sending
passwords and sensitive information.

Denial of service (DoS)
• DoS is when an attacker disables or corrupts wireless networks, systems, or
services, with the intent of denying the service to authorized users.
• DoS attacks take many forms.
• In most cases, performing the attack simply involves running a hack, script, or
tool.

Eavesdropping
• Eavesdropping is secretly or stealthily listening
to the private conversation or
communications of others without their
consent. The practice is widely regarded as
unethical, and may be illegal.

Alice
playback attack: Trudy
recordsAlice’s packet
and later
plays it back to Bob
Network Security 8-36
Alice’s
IP addr
Alice’s
password
“I’m Alice”
Alice’s
IP addr
OK
Alice’s
IP addr
Alice’s
password
“I’m Alice”

• Wireless local are network security (WLAN security) is a security
system designed to protect networks from the security breaches to
which wireless transmissions are susceptible.
• This type of security is necessary because
– WLAN signals have no physical boundary limitations
– prone to illegitimate access over network resources
– resulting in the vulnerability of private and confidential data.
– Network operations and availability can also be compromised in case
of a WLAN security breech.
• To address these issues
– various authentication mechanisms
– Encryption techniques
– invisibility and other administrative controlling techniques are used in
WLANs.
• Business and corporate WLANs in particular require adequate
security measures to detect, prevent and block piggybackers,
eavesdroppers and other intruders.
WLAN security

WLAN security technology includes:
– Wired Equivalent Privacy (WEP):
– WPA/WPA2 (WI-FI Protected Access):
– Wireless Intrusion Prevention Systems/Intrusion Detection Systems:
• Wired Equivalent Privacy (WEP):
– An old encryption standard used to overcome security threats.
– WEP provides security to WLAN by encrypting the information
transmitted over the air so that only the receivers with the correct
encryption key can decrypt the information.
• WPA/WPA2 (WI-FI Protected Access):
– Improved on WEP by introducing Temporal Key Integrity Protocol
(TKIP).
– RC4 encryption used
– TKIP uses a temporal encryption key that is regularly renewed, making
it more difficult to steal.
• Wireless Intrusion Prevention Systems/Intrusion Detection Systems:
– Intrusion detection and prevention focuses on radio frequency (RF)
levels. This involves radio scanning to detect rogue access points or ad
hoc networks to regulate network access.
– Attacks against WEP include Bit Flipping, Replay Attacks, and Weak IV
collection.

Authentication Process – Shared-Key
?
next

Performance, interoperability and
configuration of Wireless devices
Performance:- various wireless standards have different in
frequency data transfer and range
Interoperability
– Network Interoperability is the continuous ability to send and receive data among
the interconnected networks, providing the quality level expected by the end user
without any negative impact to the sending and receiving networks
– 802.11a and 802.11b work on different frequencies, so little chance for
interoperability
– Can coexist in one network
– HiperLAN/2 is not interoperable with 802.11a or 802.11b
 Configuration of wireless devices
Configuration done to communicate with other devices and to
enhance security. It is better to change the default setting
while configuring wireless devices

The WLAN security wheel
• An effective wireless security policy works to ensure that the network assets
of the organization are protected from sabotage and from inappropriate
access, which includes both intentional and accidental access.
• All wireless security features should be configured in compliance with the
security policy of the organization.
• If a security policy is not present, or if the policy is out of date, the policy
should be created or updated before deciding how to configure or deploy
wireless devices.

Simple Steps to Secure Wi-Fi Network
1. Change the Administrative Password on
your Wireless Routers.
2. Installing a Firewall.
3. Change the Default SSID Name and Turn
off SSID Broadcasting.
4. Disable DHCP.
5. Replace WEP with WPA.
How to Secure Wi-Fi Networks?

1. Change the Administrative Password on
your Wireless Routers.
• Routers came with default password to
provide easy access.
• Changing those passwords is one of the
first recommended steps to do.
• Default passwords are posted on the
vendor support sites.

2. Installing a Firewall.
• A firewall is the fence of your network
from any unauthorized accessing
• Can help in the protection of your PC by
blocking or allowing the pass to your
network.

3. Change the Default SSID Name and
Turn off SSID Broadcasting.
• In Wi-Fi a service set identifier (SSID) is a code
attached to all packets on a wireless network to
identify each packet as a part of the network.
• Changing SSID will necessitate the wireless client
computers to enter the name of the SSID by hand
before they can connect to the network.
• But even though and because the data packets that
are transmitted will include the SSID it may be
discovered.

4. Disable DHCP
• Disable the “Dynamic Host Configuration
Protocol”
• Assign IP addresses to the client
computers manually to restrict the access
to the router to specific MAC addresses.

5. Replace WEP with WPA
• WEP “Wired Equivalent Privacy” is a security protocol,
encrypting data transmitted over the wireless computer
network to provide security and privacy, and to protect the
vulnerable wireless link between clients and access points.
• But as WEP is weak and can be cracked in about 3 minutes as
the FBI showed in 2005 using some freely access tools, WPA
“Wi-Fi Protected Access” which is more powerful using 128-bit
encryption keys and dynamic session keys, must replace it to
provide strong data protection.

Man-In-The-Middle Attack is one of the attacks that can’t be
applied to wired networks, it’s just applicable to Wi-Fi.
• Hackers can configure a rogue AP to imitate a legitimate AP.
• Once the client is connected to the rogue AP, the hacker can
perform any attack that involves modifying the packet stream.
• Emails can be read, phishing attacks can be implemented etc...
Wi-Fi Special attacks

• SECURITY OF WIRELESS LOCAL AREA NETWORKS
• Summary
• Configuration considerations-Avoid default
configuration and default passwords
• industry application-
• physical configuration-locate AP in safe place
• types of transmission
–service availability-read to provide service
–signal availability-network coverage
–circuit availability
–equipment availability
• wireless network controls
• protective security mechanisms
• protection of mobile computing assets

• keeping pace with change
• determining the value of information
• computer security principles
• protecting the mobile office
• computer theft
• theft of information
• malicious code
• eavesdropping
• setting security policy

Summary
• Security definition
• Security of
– Information
– Computer
– Network
• Goal of security
• Security terminology
– Cryptology -Cryptography
– Code -Cipher
– Plan text -Secret key
– Encryption -Decryption
– Cipher text -Mono and poly alphabetic
• Security Attacks
– Snoopoing--------attacks confidentiality
– Trafic analysis
– Modefication-----Attacks Integrity
– Replaying
– Denial service ----Attacks Avilability

• Common Security Threats
 Compromised-key attack
 Network Denial-of-Service Attack
 Eavesdropping
 Identity Spoofing (IP Address Spoofing)
 Man-in-the-Middle Attack
 RTP (Real-time Transport Protocol) Replay Attack
 SPIM (Spam over Instant Messaging)
 Viruses and Worms
• WLAN security
– Important for
– How to address?
– Which organization needs
• WLAN security Technology
– WEP -WPA/WPA2
– Wireless Intrusion protection system/Wireless intrusion detection system
• System configuration, performance and interoperability
• WLAN Security wheel(Secure, monitor, test and Improve)
• How to secure wifi
 Change the Administrative Password on your Wireless Routers.
 Installing a Firewall.
 Change the Default SSID Name and Turn off SSID Broadcasting.
 Disable DHCP.
 Replace WEP with WPA.

CHAPTER 4
AN EMERGING MOBILE
(CELLULAR) NETWORK SERVICE

wireless networking chapter three WAN.pdf

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