Network security

Question 1

What is the purpose of a Denial Of Service (DOS) attack?

Answer 1

It is an attack meant to shut down a machine or network, making it inaccessible to its intended users.

Question 2

How does a DOS attack work?

Answer 2

User’s access to services is denied by using up all TCP connections (flooding the network) or sending it information that triggers a crash

Question 3

How does a Distributed Denial Of Service (DDOS) attack work?

Answer 3

• attacker infiltrates multiple hosts, using them as bots in a coordinated botnet
• attacker uses bots to flood the bandwidth and resources of the targeted system

Question 4

What are worms and viruses?

Answer 4

Worms: standalone programs that replicates itself to other host systems

Viruses: program binaries that attach themselves to other programs in order to replicate itself to other host systems

Question 5

What is a firewall?

Answer 5

A program which filters incoming and outgoing data packets, based on a set of user-defined rules

Question 6

How does a firewall protect a network from an attack?

Answer 6

A firewall checks data packets by applying filtering rules to determine if data packets are allowed to enter / go out of the network

Question 7

What are the three processes in the AAA Security Framework and their purposes?

Answer 7

Authentication: To ensure that the user is who they say they are.

Authorisation: To check that a user is authorised to access a resource.

Accounting: To keep logs of actions a user has carried out on the network.

Question 8

What is malware?

Answer 8

Malware stands for “malicious software”, intrusive software that is designed to steal data and damage or destroy computers and computer systems.

Software is considered malware based on intent of creator, not features

Question 9

Name one method to achieve each of the processes in the AAA Security Framework.

Answer 9

Auhentication: Implement a login system with multi-factor authentication/Requires users to change password regularly

Authorisation: User Account Control, Identity Management, that prevents users from accessing data without login/checks for user permissions before giving access to data/implement different roles (user, admin) with different permissions for data access

Accounting: Implement a logging system that keeps track of user actions/keeps backups of user data/archives old logs for investigation/legal purposes

Question 10

What is encryption?

Answer 10

The process of encoding data so that a secret key is required to read the data.

The key is usually provided as a sequence of bytes.

Before the data is decoded using the secret key, it appears as random, meaningless data.

Question 11

What is a digital / electronic signature?

Answer 11

It is part of a message that is used to verify:

1. the identity of the sender.
2. the message was not tampered with in transit

Question 12

What is a digital certificate?

Answer 12

An encrypted message provided by a certification authority that:

1. authenticates the identity of the individual
2. verified that the public key in the message belongs to the individual

Question 13

Describe symmetric key cryptography and its advantages and disadvantages.

Answer 13

Both the sender and the receiver have the same key.

Advantages: Security of the message does not depend on the algorithm remaining secret; key exchange is simpler as only one key is required

Disadvantages: Encryption and decryption functionality are coupled. Anyone with the key can send encrypted messages, and also decode them.

Question 14

What is a botnet?

Answer 14

collection of internet-connected devices infected by malware that allow hackers to control them.

Question 15

Name common types of malware

Answer 15

computer viruses, worms, trojan horses, bots, spyware, adware, ransomware

Question 16

What is asymmetric key cryptography?

Answer 16

A public key and private key are generated as a pair

The public key is distributed publicly and used by any sender to encrypt a message to the recipient

The private key is kept by the recipient only and used to decrypt any encrypted messages

Question 17

spyware vs keylogger

Answer 17

spyware is a malware that runs on the background of host computers, recording user activity, actions and sending that information back to the attacker

keylogger is a spyware that runs in the background of the host computer recording users mouse and keystroke movements, sending data back to attack for analysis

Question 18

what is a trojan?

Answer 18

is a malware that disguises itself as an innocent program in order to trick the user into opening it

Question 19

what is a ransomware

Answer 19

is a malware that encrypts data on the host computer rendering it unusable to legitimate users- attack usually demand money for data to be decrypted