Internet Security

Question 1

what is a firewall

Answer 1

a combination of hardware and software that isolates an organisations internal network from the internet, allowing some packets and blocking others

Question 2

what are two techniques a firewall will use

Answer 2

• packet filtering - examines packet headers and blocks or allows traffic based on predefined rules
• sateful inspection - examines the actual data of the packet. if there is no malicious code in the paxcket it will be accepeted or if the packet is part of data being sent where packets have already been recieved

Question 3

what is a proxy server

Answer 3

provides internet access to other computers on the network but is mostyly deployed to provide safety. it controls the information going in and out of the network

Question 4

give the steps of a proxy server

Answer 4

• receives a request from a client inside the firewall
• sends this request to the remote server outside of the firewall
• reads the response
• sends it back to the client

Question 5

what is encyrption

Answer 5

uses an algorithm to convert a message into a form that is not understandable without the key to decrypt it

Question 6

what is symmetric encyption

Answer 6

the same key is used to encyrpt and decrypt a message

• it is fast but requires a secure way to share a key

Question 7

what are the problems with symmetric encryption

Answer 7

the key must be sent with the message so it is vulnerable to interception

Question 8

what is asymmetric encyrption

Answer 8

one key is made publicily available and the other way is kept secret by its owner.
* public key is used to encrypt a message and the private key is used to decrypt the message

Question 9

the communication will be made more secury by the use of a ……. attached to the end of the message

Answer 9

digtal signature

Question 10

what does a digital signature do

Answer 10

confirms the identity of a sender and detects if a message has been changed

Question 11

explain how to produce a digital signature

Answer 11

• the message is hashed into a message digest whihc is encrypted with the senders private key
• this is transmitted with the message
• the receiver decrypts the signature using the senders public key
• recalculate the hash from the received message
• compares the two hashed and if the match the message is authentic and unchanged

Question 12

what is a computer virus

Answer 12

attaches itself to a program or file enabling it to spread from one computer to another, leaving infections as it travels

Question 13

What is a digital certificate?

Answer 13

A file issued by a Certificate Authority (CA) that verifies the owner of a public key, ensuring secure communication.

Question 14

what enables a virus to spread

Answer 14

a virus cannot be spread without human interaction

Question 15

what is a worm

Answer 15

• subclass of a virus
• worms spread from computer to computer but unlike a virus it the capability to travel without any human interaction

Question 16

what is a trojan horse

Answer 16

• will appear to be useful software but will do damage once installed
• those on the receiving end of trojan horse are usually tricked into opening them because they appear to be legitimate
• when activated, the results can vary from beungannoying (changed icons) to seriius damage (removing information)

Question 17

whats the difference trojan horse has compared to viruses and worms

Answer 17

trojan horses do not reproduce by infecting other files nor do they self replicate

Question 18

How can improved code quality, monitoring, and protection help prevent malware?

Answer 18

• secure code practices reduce vulnerabilities
• monitering can detect susicious activity
• protection (firewalls, antivirus) blocks threats before they spread

Question 19

explain 4 different ways that a firewall can protect computers on a LAN (4 marks)

Answer 19

• packet filtering - inspects the packet headers and blocks or allows pakcets based on predefined rules
• stateful inspection - examines the actual data of the packet. if there is no malicious code in the paxcket it will be accepeted
• identify unusual activity from the host
• a log is kept which records the entire history

Question 20

A business is worried about malware attacks. Give three methods they can use to protect their systems. (3 marks)

Answer 20

Use antivirus software to detect and remove threats. (1 mark)

Regularly update software to fix security vulnerabilities. (1 mark)

Train employees on phishing and social engineering risks. (1 mark)