Computing✧˖°.

• Passive attacks When a hacker easedrops on a network by 'sniffing' data packets
• Active attack When someone uses malware or other technical methods to compromise a network's security
• Insider attack When someone in an organisation gives away sensitive information/access details
• Social engineering When someone is exploited into giving away critical information that gives access to network or accounts
• Penetration testing When an organisation itself hires someone to carry out attacks on their company to identify vulnerabilities
• What will a good penetration testing check? Technical vulnerabilities Likelihoods of social engineering Test of damage recovery
• Malware Any kind of malicious software that is in your computer without your knowledge
• Virus Small pieces of code which spread from computer to computer
• Worm attacks Small pieces of code which spread across a network, its similar to a virus but does not have a host program
• Trojan horses Form of malware which tricks the user into installing it by pretending to be a different program
• Ransomware When a hacker encrypts files on an infected system and will only decrypt them when a payment has been made to a hacker
• Spyware Gathers information about a user by tracking activity
• Rootkits Malware which modifies the computer's operating system to avoid detection by anti-virus softwares
• Backdoors: Malware which opens up an access channel to a computer that other malware can use to take over the machine
• Phishing When fake emails and websites trick people into giving away sensitive data, a scam
• Brute force attack When a hacker tries to crack a password by trying every single combination of letters and numbers until the correct one is right
• What kinds of protection against password cracking are there? Writing a network policy which enforces strong passwords Using two-factor authentication can prevent hackers from logging Restricting number of failed password attemps before an account is locked
• DoS (denial of service) Attacks that attempt to bring down a server by flooding it with lots of useless requests. Its aim is to overload the server, which stops it from responding to real requests.
• Protection against DDoS or DoS Firewalls can ban traffic from IP addresses which are known to perform DoS attacks - they can also monitor traffic in real time, so if a new IP address starts to send lots of requests, then traffic limits can be set
• DDoS An attack when requests are sent from lots of machines (botnets). They send lots of simultaneous requests to overcome the blacklisting of an IP address.
• Data interception protection Encrypting data User access levels Network policies Educating users
• Structured Query Language (SQL) A language used to access database for storing and processing information
• Protection against SQL Input validation (username/password) User access levels
• Network policy A written document written by a company that sets out details about how their network should be set up and maintained
• Role of firewall Inspect and filter incoming and outgoing data packets (packet filtering)
• Encryption Process of scrambling data according to a specific algorithm so it cannot be read by other people. Only the intended person will know how to decode it.
• Two types of geographical network classification LAN (Local area network) and WAN (Wide area network)
• What can the value of a bit be? 1 or 0
• Pyramid of data Bit, nibble (4 bits), byte (8 bits), kilobyte (1000 bytes), megabyte (1000 kilobytes), gigabyte (1000 megabytes), Terabyte (1000 gigabytes)
• What is hexadecimal? A positional number system which is based on 16's
• How do you convert from binary to hexadecimal? - Group the binary into groups of 4 bits - Start grouping from the right hand side - Convert each 4 bit group separately
• How to convert hexadecimal to binary - Split each digit into 4 bits - Separately convert each hexadecimal digit into 4 bits of binary - Put all of the 4 groups together
• How to convert hexadecimal to denary - Write out the powers of 16 above each hexadecimal digit - For each place column, multiply the hexadecimal digit by the power of 16 above it - Add together all of the results
• How to convert denary to hexadecimal - Convert the denary to binary - Then turn the binary into hexadecimal
• Advantages of hexadecimal numbers - 8 bit binary number can be represented with 2 hexadecimal digits, so you can reduce processing time - Easier and faster to type two digits then the full binary sequence - Easier for a human to process than binary - Reduces chances for error
• When is hexadecimal numbers used? - Machine code - Assembly - To debug writing programs as it is easy to process by humans - To represent numbers used in a CPU's registers or in main memory
• What is the range of numbers that can be represented as a single byte? 0 - 255, 2 hexadecimal digits represent each RGB (red, green, blue) value. The HTML colour code has 3 pairs of hexadecimal digits, each showing one colour
• What happens when you add 0s and 1s? 0 + 0 = 0 1 + 0 = 1 1 + 1 = 0 carry 1 1 + 1 + 1 = 1 carry 1
• What is an overflow error? When a number is carried past the last column during binary addition, can lead to inaccurate results and software crashes.
• What is binary shift? A technique for performing multiplication or division on a binary number. Each digit is moved one column to the left or the right, extra 0 bits are added to the start or end of the binary number to fill any missing spaces.