comp sci (4+5/10)

forms of attack on a network:

• Malware

• Social engineering: phishing

• Brute-force attacks

• Denial of service attacks

• Data interception & theft

• SQL injection

malware

-types of malware

-any software that has been created with malicious intent to cause harm to a computer system

-virus, worms, trojan, spyware, ransomware

what malware can do

-Files being deleted, corrupted or encrypted

-Internet connection becoming slow or unusable

-Computer crashing or shutting down 

virus=

-A program which can replicate itself on a user's computer. It contains code that will cause unwanted and unexpected events to occur

• Examples of issues a user may experience are

  • Corrupt files

  • Delete data

  • Prevent applications from running correctly

worms=

-how do users get them

-are very similar to viruses, with the main difference being that they will spread to other drives and computers on the network

• Worms can infect other computers from

  • Infected websites

  • Instant message services

  • Email

  • Network connection

trojan/ trojan horse=

disguise themselves as legitimate software but contain malicious code in the background 

spyware=

-where from

-Software which will allow a person to spy on the users' activities on their devices

-This form of software will be embedded into other software such as games or programs that have been downloaded from illegitimate sources

-Spyware can record your screen, log your keystrokes to gain access to passwords and more

ransomeware=

-form of malware that locks your device and encrypts your documents and other important files

-Often a demand is made for money to receive the password that will allow the user to decrypt the files

-There is no guarantee paying the ransom will result in the user getting their data back

What is social engineering?

-is exploiting weaknesses in a computer system by targeting the people that use or have access to them

phishing=

Sending deceieving emails to a large number of email addresses, claiming to be from a reputable company or trusted source to try and gain access to your details, often by coaxing the user to click on a login button

why r people seen as a weak point in a system

-Not locking doors to computer/server rooms

-Not logging their device when they're not using it

-Sharing passwords

-Not encrypting data

-Not keeping operating systems or anti-malware software up to date

brute force attack=

+e.g.

works by an attacker repeatedly trying multiple combinations of a user's password to try and gain unauthorised access to their accounts or devices

-e.g. an attacker finding out the length of a PIN code, for example, 4-digits OR trying popular words or phrases

Denial of Service Attack (DOS attack) =

-occurs when an attacker repeatedly sends requests to a server to flood the server with traffic, causing it to overload the system

-The server will slow down to the point of becoming unusable 

purpose of a DOS attack

-will prevent customers from accessing or using a service

-This will result in companies losing money and not being able to carry out their daily duties

-A DOS attack can cause damage to a company's reputation

Data interception and theft=

-when thieves or hackers can compromise usernames and passwords as well as other sensitive data

-This is done by using devices such as a packet sniffer

-A packet sniffer will be able to collect the data that is being transferred on a network

-A thief can use this data to gain unauthorised access to websites, companies and more 

what is SQL

-Structured Query Language (SQL) is a language used to create, access and manipulate a database

what is SQL injection

-is entering an SQL command into a web text field to manipulate the SQL query

-The goal is to insert, modify or delete data from the database

• An example of SQL injection would be a user typing in a query such as

  • SELECT UserId, Name, Password FROM Users WHERE UserId = 100 or 1=1;

  • This would return all of the User IDs, Names and passwords because 1 is always equal to 1

shouldering/ shouler phishing=

-watching what a user is doing on a comp over a victims shoulder

-common w ATMS

adware=

-s.w. displays advert

-collects data ab the user 4 marketing

-often hidden within freeware s.w.

-can cause problems: pop-up window sm change of home page

penetration testing=

-a method of preventing vulnerabilities whereby a company employ people to try and hack their network and databases

-This allows the 'hackers' to point out the parts of the system that are vulnerable 

-The companies then use this information to fix the issues that are found

what form of attack wld penetration testing prevent

SQL injection

anti-malware software=

term used to describe a combination of different software to prevent computers from being susceptible to viruses and other malicious software

diff types of anti malware s.w.

• Anti-virus 

• Anti-spam 

• Anti-spyware 

How does anti-malware work?

-scans through email attachments, websites and downloaded files to search for issues

-has a list of known malware signatures to block immediately if they try to access your device in any way

-also performs checks for updates to ensure the database of known issues is up to date

What form of attack would anti-malware prevent?

against any form of malicious software

firewall=

-hardware and s.w.

-a barrier between a network and the internet

-prevents unwanted traffic from entering a network by filtering requests to ensure they are legitimate

• It can be both hardware and software and they are often used together to provide stronger security to a network

  • Hardware firewalls will protect the whole network and prevent unauthorised traffic

  • software firewalls will protect the individual devices on the network, monitoring the data going to and from each computer

what does a firewall prevent

• Hackers

• Malware

• Unauthorised Access to a Network

• DOS/DDOS attacks

user access levels=

ensure users of a network have designated roles on a network

-e.g. Administrators: Unrestricted - Can access all areas of the network

password=

a digital lock to prevent unauthorised access to an account

what form of attacks do pasw prevent

• Data Interception and Theft

• Physical Security Issues

• SQL Injection

what form of attack does encryption prevent

does not prevent the attacks from occurring but it does stop the attacker from gaining access to the information

physical security=

-a method of physically preventing access to any part of a network

• There are a range of physical security measures that can be implemented on a network

  • Locked doors: Preventing access to server rooms and cabinets of switches

  • Biometrics: Fingerprint scanners, facial recognition and retinal scans 

what form of attack does physical security prevent

• Data interception and theft

• Social engineering

Q)A web development company wants to protect their computer systems and data from unauthorised access.

Identify and describe two software-based security methods that the company can use to protect their computer systems and data. [6]

• Anti-malware

  • Scans for / identifies virus/spyware/malware

  • Compares data to a database of malware

  • Alerts user and requests action

  • Quarantines/deletes virus/spyware/malware

  • Stops the download of virus/spyware/malware

• Firewall

  • Scans incoming and outgoing traffic

  • Compares traffic to a criteria

  • Blocks traffic that is unauthorised

  • Blocks incoming/outgoing traffic

• Encryption

  • Scrambles data using an algorithm

  • So if intercepted it cannot be understood

  • Key needed to decrypt

• User access levels

  • Data can be read/write/ read-write

  • Prevents accidental changes

  • Limits data users can access

• Passwords/biometrics/authentication code/fingerprint

  • Has to be correctly entered to gain access

  • Strong password // letters, numbers, symbols // fingerprint is unique to individual

  • Harder/impossible for a brute-force attack to succeed

  • Lock after set number of failed attempts

what is an operating system (os)

-software that provides an interface between the user and the hardware in a computer system

• An operating system hides the complexities of the hardware from the user, for example:

  • A user does not need to know 'where' on secondary storage data is kept, just that it is saved for when they want it again

5 main functions of an os

• Provide a user interface

• Memory management & multitasking

• Peripheral management & device drivers

• User management

• File management

user interface=

-e.g.s

is how the user interacts with the operating system

-Command Line Interface (CLI)

-Graphical User Interface (GUI)

-Menu

-Natural language (NLI)

command line interface =

-requires users to interact with the operating system using text based commands

-CLIs are more commonly used by advanced users

graphical user interface =

-requires users to interact with the operating system using visual elements such as windows, icons, menus & pointers (WIMP)

-GUIs are optimised for mouse and touch gesture input

menu interface=

+e.g.

-successive menus presented to a user with a single option at each stage

-Often performed with buttons or a keypad

-vending machines

natural language interface=

-e.g.s

-uses the spoken word to respond to spoken or textual inputs from a user

-Virtual assistants - Amazon Alexa, Google Assistant, Siri + Search engines

pros + cons of each interface

yes

memory management=

+purpose

-data is transferred between the device and processor

-programs removed from RAM when completed to free up space for other tasks

-process carried out by the operating system allocating main memory (RAM) between different programs that are open at the same time

- OS is responsible for copying programs and data from secondary to primary storage as it is needed

-Programs and data require different amounts of RAM to operate efficiently and the OS manages this process

-RAM is allocated based on priority and fairness, for example, system applications (essential) may have a higher priority than user applications

-The OS dynamically manages the memory, adjusting allocation as needed to maintain optimal system performance

-Memory management makes multitasking possible

multi tasking=

-hows it made

-process made possible by the OS simultaneously managing system resources (memory, CPU etc) to give a user the perception of being able to use multiple programs at the same time

-The OS splits tasks and allocates system resources based on a priority

-The CPU can only execute one instruction at a time, it can can execute billions of them in one second.

-This makes it appear that multiple programs are running at the same time

peripheral management=

-process carried out by the operating system managing the way peripherals (hardware) interact with software

-The OS allocates system resources to peripherals to ensure efficient operation

-Peripheral management makes plug-and-play (PnP) functionality possible, automatically detecting and configuring new peripherals without the need for manually installing device drivers or power cycling the system

device driver=

-provides an interface for the os to interact and communicate with the peripheral.

-piece of software used to control a piece of hardware

-Peripherals require device drivers in order to be used by the operating system

-The OS has generic device drivers built in which makes basic compatibility possible and enables plug-and-play (PnP)

-In order for hardware to be used to its maximum capacity, often a separate device driver must be downloaded from the manufacturer

-Device drivers are OS specific and are regularly updated

-hardware dependant

user management=

-os allows to create, manage and delete individual accs

-process carried out by the operating system enabling different users to log onto a computer

-OS is able to maintain settings for individual users, such as desktop backgrounds, icons and colour schemes

-A system administrator is able to allocate different access rights for different users on a network

file management=

-process carried out by the operating system creating, organising, manipulating and accessing files and folders on a computer system

-allows files to be named, opened, copied, moved, saved, sorted and deleted

-The OS manages where data is stored in both primary and secondary storage

-allows users to set access rights for specific files and to view file properties

-The OS provides a search facility to find specific files based on various criteria

file management gives the user the ability to

• Create files/folders

• Name files/folders

• Rename files/folders

• Copy files/folders

• Move files/folders

• Delete files/folders

Q)Ella uses her computer to create artwork for a magazine

Ella makes use of system software.

One type of system software is the operating system.

Identify and describe two functions of an operating system [6]

• Memory management

  • Allocates memory to programs currently in use 

  • Gets data from RAM

  • Stores data in RAM

• File management

  • Creating/editing/renaming files

  • Creating/editing/renaming folders

  • Movement of files/folders

utility s.w.=

-software designed to help maintain, enhance and troubleshoot/repair a computer system

-Utility software is designed to perform a limited number of tasks not performed by o.s.

-Utility software interacts with the computers hardware, for example, secondary storage devices

-Some utility software comes installed with the operating system

defragmentation

Fragmentation:

-fragmentation occurs when there is limited space to store a file on a hdd

-files r split into parts that r saved in diff storage locations

-fragmentation increases access times

-files that r fragmented take longer to load and read because of the distance between the fragments of the files

Defragmentation:

-Defragmentation software groups fragmented files back together in order to improve access speed

-As programs and data are added to a new hard disk drive, it is added in order, over time as files are deleted this leaves gaps

-empty spaces are collected together on the hard disk drive and file fragments are moved to be stored together

-As programs and data are added over time, these gaps get filled and data becomes fragmented

-Defragmentation can only used on magnetic storage

-faster access times cus read write head doesn’t need. to move as far

e.g.s of a utility s.w.

-defragmentation, compression, encryption, task manager, anti-malware

pros

compression=

-reduces the amount of secondary storage required by performing an algorithm on the original data

pros: -files take up less storage space

-files can be transferred quicker

-files can be read from or written to quicker

-Lossy compression physically removes data using an algorithm from the original data to reduce its size, the original file can not be re-created → used in audio, images, videos

-Lossless compression uses algorithms to order data more efficiently reducing its size, the original files can be re-created as no data is lost → used in files, games, word documents

task manager=

-software that is built into the operating system to allow users to monitor system resources in order to help troubleshoot potential problems

-Task manager gives system information such as: Processes, Performance, App history, Start-up app, Users, Services

Q)A hotel has a computer-based booking system which is running slowly. A technician has
said that the hard disk drive is fragmented. The technician has suggested using utility software to defragment the drive.

Explain how the hotel’s hard disk could have become fragmented [4]

• Booking have been saved onto the system and then deleted once completed [1]

• New bookings are created [1] which may need more space than the completed ones left behind [1]

• The booking files are split up [1]