Security Awareness: Applying Practical Security in Your World, Second Edition

Security Awareness: Applying Practical Security in Your World, Second Edition Chapter 5 Network Security

Objectives • Explain how a network functions • Discuss how to defend against network attacks • Describe the types of attacks that are launched against networks and network computers Security Awareness: Applying Practical Security in Your World, 2e

How Networks Work • Personal computer • Isolated from other computers • Functionality is limited to installed software and hardware directly connected to it • Computer network • Allows sharing Security Awareness: Applying Practical Security in Your World, 2e

Security Awareness: Applying Practical Security in Your World, 2e

Types of Networks • Local area network (LAN) • Computers located relatively close to each other • Wide area network (WAN) • Connects computers over a larger geographical area than a LAN • Wireless local area network (WLAN) • Based on standard that transmits data at fast speeds over a distance of up to 115 meters (375 feet) Security Awareness: Applying Practical Security in Your World, 2e

Transmitting Network Data • Transmission Control Protocol/Internet Protocol (TCP/IP) • Most common set of protocols used on networks • IP address • Uniquely identifies computer • Packets • Used to transmit data through a computer network Security Awareness: Applying Practical Security in Your World, 2e

Network Devices • Network interface card (NIC) • Also called client network adapter • Hardware that connects a computer to a wired network • Laptop computers • May use an internal NIC or an external NIC Security Awareness: Applying Practical Security in Your World, 2e

Network Devices (continued) • Access point (AP) • Contains an antenna and a radio transmitter/receiver to send and receive signals • Jack allows it to connect by cable to a standard wired network • Acts as base station for wireless network • Acts as bridge between wireless and wired networks • Router • Directs packets towards their destination Security Awareness: Applying Practical Security in Your World, 2e

Attacks on Networks • Denial of service (DoS)attack • Attempts to make a server or other network device unavailable by flooding it with requests • Variants • Smurf attack • Distributed denial of service (DDoS)attack Security Awareness: Applying Practical Security in Your World, 2e

Zombie and Botnets • Computers that perform a DDoS and other network attacks • Often normal computers hijacked by attackers to carry out malicious network attacks • Zombies • Can be put to work to send spam and messages used in phishing scams • Can act as hosts for fake Web sites Security Awareness: Applying Practical Security in Your World, 2e

Man-in-the-Middle Attacks • Attacker intercepts messages intended for a valid device • Two computers appear to be communicating with each other • However, they are actually sending and receiving data with a computer between them Security Awareness: Applying Practical Security in Your World, 2e

Hijacking and Spoofing • Spoofing • Act of pretending to be legitimate owner when in reality you are not • Media access control (MAC)address • Permanently recorded on network interface card when manufactured • Computers on network store a table • Links IP address with corresponding MAC address Security Awareness: Applying Practical Security in Your World, 2e

Sniffing • Attacker captures packets as they travel through network • Sniffer • Hardware or software that performs sniffing • Attackers with sniffers • Can capture usernames, passwords, and other secure information without being detected Security Awareness: Applying Practical Security in Your World, 2e

Network Defenses • Primary defenses against network attacks • Devices that can thwart attackers • Designing layout or configuration of a network that will reduce the risk of attacks • Testing network security Security Awareness: Applying Practical Security in Your World, 2e

Network Devices • Firewalls • Designed to prevent malicious packets from entering network or computers • Software firewall • Runs as a program on a local computer to protect it against attacks • Hardware firewalls • Separate devices that protect an entire network • Usually located outside network security perimeter as the first line of defense Security Awareness: Applying Practical Security in Your World, 2e

Firewalls • Rule base • Foundation of a firewall • Establishes what action firewall should take when it receives a packet • Options • Allow, Block, Prompt Security Awareness: Applying Practical Security in Your World, 2e

Firewalls (continued) • Stateless packet filtering • Looks at each incoming packet and permits or denies it based strictly on the rule base • Attackers can easily bypass the protection • Stateful packet filtering • Keeps record of the state of a connection between an internal computer and an external server • Makes decisions based on the connection as well as rule base Security Awareness: Applying Practical Security in Your World, 2e

Network Address Translation (NAT) • Hides IP addresses of network devices from attackers • As a packet leaves the network • NAT removes original IP address from sender’s packet and replaces it with an alias Security Awareness: Applying Practical Security in Your World, 2e

Network Address Translation (NAT) (continued) • NAT software • Maintains table of original address and corresponding alias address • Process is reversed when packet is returned to the NAT Security Awareness: Applying Practical Security in Your World, 2e

Intrusion Detection System • Establishes and maintains network security for large organizations • Monitors activity on the network and what packets are doing • Performs specific function when it senses an attack • Such as dropping packets or tracing source of attack Security Awareness: Applying Practical Security in Your World, 2e

Proxy Server • Primary goal • To conceal the identity of computers within a protected network • Can inspect data packets for viruses and other malicious content • Intercepts requests sent to server and replaces original IP address with its own address Security Awareness: Applying Practical Security in Your World, 2e

Network Design • Demilitarized zone (DMZ) • Another network that sits outside the secure network perimeter • Virtual private network • Creates a secure network connection over a public network Security Awareness: Applying Practical Security in Your World, 2e

Wireless LAN Security • Hotspots • Locations where wireless data services are available • Advantages of WLANs • Do not restrict users to their desks to access network resources • Ease of installation Security Awareness: Applying Practical Security in Your World, 2e

Wireless LAN Security (continued) • Security concerns • Access to the wireless network • View wireless transmissions • Weaknesses in wireless security standards Security Awareness: Applying Practical Security in Your World, 2e

Summary • Purpose of a computer network • To allow computers and devices to share data, programs, and hardware • Denial of service attack • Attempts to make a server unavailable by flooding it with requests • Man-in-the-middle attack • Intercepts communication between two computers Security Awareness: Applying Practical Security in Your World, 2e

Summary (continued) • Firewall • Designed to prevent malicious packets from entering the network • Demilitarized zone • Another network that sits outside the secure network perimeter • Security for wireless LANs • Remains a primary concern for wireless users Security Awareness: Applying Practical Security in Your World, 2e

Security Awareness: Applying Practical Security in Your World, Second Edition