Component 1 Exam Preparation
Download the latest mock exam and use your books to find the answers to the questions! This is fantastic preparation for your final exam on Monday 13th May!
Component 1 Exam Revision
Check out the GCSE theory topics on CS Newbs! A great revision website for your upcoming mock exam that is specific to the EDUQAS exam!
Of course, use the Craig 'n' Dave video resources too.
And make sure you use the Sample Assessment Materials (SAMs) to help you prepare for the examination (ask for other past papers from your teacher).
Of course, use the Craig 'n' Dave video resources too.
And make sure you use the Sample Assessment Materials (SAMs) to help you prepare for the examination (ask for other past papers from your teacher).
Foldables
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Use your revision books! Here are some topics to get you going...
Malware (malicious software)
Viruses
- malicious programs that replicate themselves by attaching themselves to host files enabling them to spread from one system to another
- they modify and corrupt files to make them unusable
Worms
- malicious programs, like viruses, but they are self-replicating (do not need a host file)
- exploit bugs in legitimate software.
Spyware
- installed by opening attachments or downloading infected software
- used to collect stored data without the user’s knowledge.
Trojans
- a program that appears to perform a useful function, but actually provides a ‘backdoor’ that enables data to be stolen.
Keylogger
- spyware that can be used to track keystrokes and capture bank account numbers/passwords for fraudulent use.
Protect Against Malware
Install Anti-Virus Software
- details (called 'signatures') of known virus files are stored in a database
- the software scans files to check if any of the signatures match with any files on the system
- if a match is found the virus is deleted.
Install Firewall Software
- monitors incoming and outgoing network traffic for data packets that are unexpected.
Keep Operating Software Up To Date
- install 'security patches' to fix vulnerabilities that have been found in the software.
Look Out For Phishing Emails
- Usually they are caught by the spam filter, but be suspicious about emails asking for sensitive information.
Malware Removal Tool
- Download and run this tool to remove malware that might be missed by anti-virus
Cybersecurity Attacks
Shoulder surfing
- uses direct observation to get information
- it is relatively simple to stand next to someone and watch as they fill out a form, or enter a PIN number, but shoulder surfing can also be carried out long distance with the aid of binoculars or even CCTV.
DOS Attack (Denial Of Service)
- a DOS attack is when multiple fake requests (for data) are sent to the web server which causes it to crash because it cannot cope the high volume of traffic.
SQL Injection
- SQL injection is a technique where malicious users can inject SQL commands into an SQL statement, via web page input.
- Injected SQL commands can alter SQL statements and compromise the security of information held in a database.
IP address spoofing
- IP address spoofing involves an attacker changing the IP address of a legitimate host so that a visitor who types in the URL of a legitimate site is taken to a fraudulent or spoofed web page.
- The attacker can then use the hoax page to steal sensitive data, such as a credit card number, or install malware.
Password Attacks
- Dictionary attack - simple file containing words found in a dictionary
- Brute force attack - similar to the dictionary attack but able to detect non-dictionary words by working through all possible alphanumeric combinations
- Guess - Educated guesses often work.
How to Identify Cybersecurity Vulnerabilities
Footprinting
- Footprinting is the first step in the evaluation of the security of any computer system.
- It involves gathering all available information about the computer system or network and the devices that are attached to it.
- Footprinting should enable a penetration tester to discover how much detail a potential attacker could find out about a system
- and allow an organisation to limit the technical information about its systems that is publicly available.
Ethical hacking
- Ethical hacking is carried out with the permission of the system owner to cover all computer attack techniques.
- An ethical hacker attempts to bypass system security and search for any weak points that could be exploited by malicious hackers.
- This information is then used by the system owner to improve system security.
Penetration testing
- Penetration testing is a sub set of ethical hacking that deals with the process of testing a computer system, or network to find vulnerabilities that an attacker could exploit.
- The tests can be automated with software applications or they can be performed manually.
Penetration test strategies include:
- Targeted testing, testing carried out by the organization's IT team and the penetration testing team working together.
- External testing, to find out if an outside attacker can get in and how far they can get in once they have gained access.
- Internal testing, to estimate how much damage a dissatisfied employee could cause.
- Blind testing, to simulate the actions and procedures of a real attacker by severely limiting the information given to the team performing the test.
Social Engineering
- tricking a user into giving out sensitive information such as a password, by posing as a legitimate organisation or system administrator.
- E.g. phishing - uses fake emails and websites to manipulate users into giving out personal information
- E.g. pharming - users are unknowingly re-directed to a fake website, again with the intention of identity theft.
Converting Expressions into Truth Tables
Binary to Denary
- Binary is a base-2 number system consisting of only 2 values, which are 0 and 1.
- The number system works in the same way as our regular number system (denary), except the place values increase from right to left by the power of 2 (instead of by the power of 10)
- In other words, they double up - so the place values start at 1 then increase to 2, then to 4, then to 8, then to 16, etc.
- Here is an example of converting binary 10010111 into denary:
Binary to Hex Conversion
- To convert binary to hexadecimal is straightforward.
- Firstly, you need to remind yourself of the Hexidecimal values and the Denary numbers they are equivalent to:
- Now, using an example binary number of 11110011, we need to split the byte (8 bits) into 2 halves.
- Then convert both nibbles (4 bits) into denary and then into the equivalent hex number, like this:
- So binary number 11110011 is equivalent to the hexadecimal number F3.
Binary Addition
The rules for binary addition:
0 + 0 = 0
0 + 1 = 1
1 + 1 = 0 carry 1
1 + 1 + 1 = 1 carry 1
Sometimes, two 8-bit numbers (bytes) added together can produce a 9-bit answer. This is known as an overflow error because one bit of data is lost (9 bits don't fit into a byte).
For example:
0 + 0 = 0
0 + 1 = 1
1 + 1 = 0 carry 1
1 + 1 + 1 = 1 carry 1
Sometimes, two 8-bit numbers (bytes) added together can produce a 9-bit answer. This is known as an overflow error because one bit of data is lost (9 bits don't fit into a byte).
For example:
TCP/IP 5 Layer Model
The TCP/IP 5 Layer Model is essentially a rule book for how computers communicate with each other across a network. Networking is a very complex operation so the 5 layer model is used to try to simplify how data is gets from one node to another. Think of networking as having 5 different layers and each layer has different responsibilities:
Application Layer (protocols include HTTP, FTP, SMTP, and POP3) - This layer provides software (like email) to users on the network.
Transport Layer (TCP protocol) - This layer handles sequencing to ensure data packets are transferred reliably between two nodes on a WAN.
Internet Layer (IP protocol) - This layer routes data packets to their destination (using IP Addresses)
Data Link Layer (Ethernet protocol) - This layer formats data for transmission. It divides data into frames (a data link header and data packet).
Physical Layer - This layer transfers bits over a physical connection (i.e. using wires and a NIC or router).
Application Layer (protocols include HTTP, FTP, SMTP, and POP3) - This layer provides software (like email) to users on the network.
Transport Layer (TCP protocol) - This layer handles sequencing to ensure data packets are transferred reliably between two nodes on a WAN.
Internet Layer (IP protocol) - This layer routes data packets to their destination (using IP Addresses)
Data Link Layer (Ethernet protocol) - This layer formats data for transmission. It divides data into frames (a data link header and data packet).
Physical Layer - This layer transfers bits over a physical connection (i.e. using wires and a NIC or router).
Protocols
Ethernet defines how data needs to be formatted for transmission using frames / packets.
HTTP (hypertext transfer protocol) allows webpages to be shared across different computers and browsers.
HTTPS is a secure version of HTTP – it works together with another protocol, Secure Sockets Layer (SSL), to transport data securely.
HTTPS is a secure version of HTTP – it works together with another protocol, Secure Sockets Layer (SSL), to transport data securely.
POP3 is for receiving email from a mail server, where the email is stored until a client (e.g. Outlook) is ready to download it.
SMTP is for sending messages to a mail server.
IMAP is an alternative to POP3 for receiving email.
FTP is for transferring files from a computer to a web server.
Metadata
Data that describes other data, e.g.
Data that describes other data, e.g.
- for a graphics file – date created, width, height, colour depth, resolution, etc.
- for a sound file – date created, sample rate, bit depth, etc.
Compression
- When you convert a file to a lossy format you discard some of the data / lose quality
- If you then try to convert the lossy format to a lossless format, the lost data will not be recovered!
Calculate file size of a graphic (image)
Using an example of a graphic file with dimensions of 50 x 80 pixels and a colour depth of 8-bit, you can calculate the file size using the following instructions:
Using an example of a graphic file with dimensions of 50 x 80 pixels and a colour depth of 8-bit, you can calculate the file size using the following instructions:
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In the exam, you must show all of your working out!
For practice, imagine you have a graphic that is 40 x 60 pixels with a colour depth of 16-bit. Use the instructions above to work out the file size in kilobytes.
For practice, imagine you have a graphic that is 40 x 60 pixels with a colour depth of 16-bit. Use the instructions above to work out the file size in kilobytes.
Central Processing Unit (CPU)
- Control Unit – directs the flow of instructions and/or data.
- ALU – performs mathematical calculations and logical operations.
- Clock speed – the higher the clock speed (measured in Hz), the more instructions are processed each second.
- Cores – quad-core can process more instructions simultaneously than dual-core (it's twice as fast).
- Cache size – more cache means more instructions are stored on the CPU rather than in RAM so they are processed at a much faster rate.
RISC type processors
- stands for Reduced Instruction Set Computer
- processes a limited number of simple instructions.
CISC type processors
- stands for Complex Instruction Set Computer
- processes a large number of complex instructions.
CPU Clock Speed
Clock speed is measured in GHz (G stands for Giga, which means million - so 10GHz means 10 billion hertz).
If one CPU has a higher clock speed than another, it will process more instructions.
If one CPU has a higher clock speed than another, it will process more instructions.
CPU Cores
CPU can have multiple 'cores' (e.g. dual, quad, etc.).
If a CPU has more cores than another, it means that data/instructions can be processed simultaneously (at the same time!)
So in theory, a dual core processor will process data/instructions twice as fast as a single core processor.
If a CPU has more cores than another, it means that data/instructions can be processed simultaneously (at the same time!)
So in theory, a dual core processor will process data/instructions twice as fast as a single core processor.
CPU Cache
Cache is part of the CPU used to store frequently used data.
If a CPU has a higher cache size than another, data will be provided to the CPU at a faster rate.
If a CPU has a higher cache size than another, data will be provided to the CPU at a faster rate.
Fetch-Decode-Execute Cycle
- when a program is starts, its instructions are loaded into main memory (RAM).
- when an instruction is needed, it is fetched by the CPU from RAM
- the CPU decodes and executes the instruction
- data from the executed instruction is written to RAM.
Utility Software
- Defragmentation - files are physically re-arranged on disk so that segments are no longer spaced apart, which makes them quicker to access.
- Compression - software reduces file sizes using less space.
- Task management - can see how much disk % a given program is using, can shut it down if dominating.
- Disk scanning and repair - fixes problems on disk.
- Anti-virus software - to scan for viruses which could be causing issues with the disc access speed / damaging data.
- Backup - software allows users to archive files and delete files on the hard disk to free up space.
Embedded System
- small, dedicated system of hardware and software used to performs a specific task.
- permanently built into a machine so software is usually stored in ROM (called firmware).
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