Cyber Security | O Level Computer Science 2210 & IGCSE Computer Science 0478 | Detailed Free Notes To Score An A Star (A*)

Cyber Security Threats

• Personal and commercial data must be kept safe.
• Both malicious acts and accidental damage can cause the loss of data.
• Brute Force Attack
  • Not a very sophisticated technique
  • Hacker tries crack password by systematically trying all the different combination of letters, symbols and numbers
  • Number of attempts required to crack a password can be reduced through logical steps
    • Check for the most common passwords
      • Simple passwords that most people use.
    • Next, try a strong word list
      • A text file containing words that can be used in brute force attack
      • Programs can generate millions of such words
      • Still faster than total trial and error
    • Longer and more complex passwords can be very hard to crack using this technique
    • Takes a lot of time
  • Data Interception
    • Stealing the data by tapping into a wired or wireless communication link.
    • Compromise privacy and obtain confidential information
    • Packet sniffer
      • Examines packets being sent over a network
      • Intercepted data sent back to hacket
      • Commonly used in wired networks
    • Wardriving
      • Access Point Mapping
      • Used for wireless data (Wi-Fi) data
      • Intercepted using a laptop/ smartphone, GPS device and antenna.
      • Software used as well.
      • Personal data can be revealed without eh user’s knowledge
      • Need to be in close proximity to the user.
      • Safeguard
        • Encryption makes data completely incomprehensible for the hacker
          • IT DOES NOT STOP HACKING ITSELF
        • Wired Equivalency Privacy (WEP) encryption protocol + a firewall is recommended
        • Protecting wireless router with complex passwords is also important
        • Avoid wireless connectivity in public spaces
          • No data encryption is used here
          • Anyone can intercept the data.
        • Distributed Denial of Service (DDoS) Attacks
          • A denial of service (DOS)attack
            • Attempt to prevent users from accessing part of a network.
            • Usually on the internet.
            • Temporary but damaging
            • Can result in large breach of security
            • Individual targets may also occur
              • Email access denied
              • Website/ web page access denied
              • Online services denied
            • Flooding network traffic with spam
              • When a user searches for a site
              • A request is sent to the server with the website
              • Only a finite number of requests can be handled by the server at any time
              • Overloaded server with spam traffic won’t be able to cater legitimate users
            • Difference between DDoS and DoS
              • In DDoS many different computers are used to generate the spam attack
              • Therefore, it is harder to block the attack
            • In case of emails
              • Sending too many spam emails to the user’s account
              • Can clog the email
              • User can not get real emails
            • Some guard is possible
              • Up to date malware checking system
              • Firewall to restrict traffic
                • Filter unwanted traffic
              • Applying email filters to take out unwanted traffic
            • How to know a DDoS has happened
              • Slow network performance
              • Inability to access certain sites
              • Large amounts of spam emails reaching user’s email account.
            • Hacking
              • Gaining illegal access to a computer system without user’s permission
              • Identity theft
              • Personal information gained
              • Data can be deleted, changed, corrupted
              • Encryption can not stop hacking
                • It makes hacked data uselss
                • But it won’t stop the hacket from deleting, corrupting or passing the data.
              • Hacking can be prevented through firewalls
                • Usernames and strong passwords also help
                • Changing password frequently as well
                • Anti-hacking software and intrusion detection software can help as well.
              • Malicious hacking
                • Taking data without user’s permission.
                • Always illegal
              • Ethical hacking
                • Paid hackers by companies to check their security measures
                • How well their safety systems are.
              • Malware
                • Many forms
                • Viruses
                  • Programs or program codes that can replicate
                    • Create copies of themselves
                  • Intention is to corrupt the files
                  • Cause computer to malfunction
                    • Deleting .exe files
                    • Filling drive with useless data
                  • Need an active host program on the target computer
                    • This is already infected
                    • Then they can run and cause harm
                    • A trigger is required to make them work
                  • Often sent as email attachments
                  • Can be on infected website or software
                • Worms
                  • Stand-alone malware
                  • Can self-replicate
                  • Spreads to other computers and complete networks
                  • Don’t need an active host program
                  • Inside the applications that helps them move throughout networks
                  • Replicate without targeting or infecting specific files on a computer
                  • Rely on security failures within networks to spread without hindrace
                  • Often in the form of message attachments
                    • Opening it can infest entire networks
                  • Anti-virus programs can hep.
                  • Their ability to spread without any action of the user makes them really troublesome.
                  • Example is the I love you worm, attacked every email almost in the world.
                  • Even brought down television networks
                • Trojan Horse
                  • Disguised as a legitimate software
                  • Has malicious instructions inside it.
                  • Replaces all or part of the legitimate software with the intent of carrying harm
                  • Need to be executed by the user.
                  • Arrive as downloads or email attachments
                  • For example, a fake anti-virus program
                  • Can give cyber criminals access to personal information on the computer
                  • IP Addresses, passwords and other personal data can be compromised
                  • Can install spyware and ransomware.
                  • Firewalls and security systems are often useless in this regard
                    • Users can overrule them and initiate the software
                  • Spyware
                    • Gathers information by monitoring user’s activities
                    • The data is sent back to cybercriminal
                    • Monitor and capture web browsing and other activities
                    • Anti-spyware software can remove them
                    • The main issue is how did the spyware enter the user’s computer
                    • Shows a weakness in security and can show that even more dangerous malware can enter the system.
                  • Adware
                    • Type of malware
                    • It will flood the user with unwanted advertising
                    • Redirect a user’s browser to a website with promotional advertising
                    • Appear in the form of pop-ups and appear in redirects search requests
                    • It is not always harmful
                    • But it shows weakness in the security system
                    • Hard to remove as difficult to determine
                    • Can hijack a browser and create own default search requests
                  • Ransomware
                    • Encrypt data on a user’s computer and hold the data hostage
                    • Ransom money has to be paid
                    • Sometimes they send decryption key to the user
                    • Considerable damage can be caused
                    • Restricts access to the computer and all the data as it is encrypted
                    • Trojan horse or social engineering can be use to inject it in the computer.
                    • Encrypts files directly or wait to determine how much ransom the user can afford
                    • Once executed, almost impossible to reverse the damage
                    • Regular backups of key files is important
                  • Phishing
                    • When a cybercriminal sends out legitimate looking emails to users
                    • Contains links or attachments that can fake a website and gain personal data by tricking the user
                    • It feels like the email is usually coming from a legitimate bank or service provider
                    • Some action must be done by recipient for any damage or harm to occur
                    • If emails are detected or not opened, it causes no harm
                    • How to prevent
                      • Awareness is important – security training provided
                      • Don’t open emails that look unsafe
                      • Anti-phishing toolbars to alert if phishing is occurring
                      • https sign must be considered on sites to check if data is encrypted on transfer.
                      • Regularly check online accounts and maintain passwords
                      • Up to date browsers
                      • Firewalls at all times
                      • Both software and hardware firewalls (desktop and network firewalls)
                      • Block wrong pop-ups
                    • Spear phishing
                      • Specific individuals or companies are targeted to get sensitive financial information
                      • Industrial espionage occurs
                      • Regular phishing is not concerned with who is the target.
                    • Pharming
                      • Malicious code is installed on user’s computer or infected wesite
                      • Redirects to a fake website without user’s knowledge
                      • No action is required to initiate it.
                      • Personal data can be taken
                      • The websites often look real
                      • DNS cache poising
                        • The browser contacts the DNS server when a URL is typed
                        • IP address of the website will be sent back to the browser
                        • DNS cache poising changes the real IP with fake website values
                        • User’s computer connects to the fake website
                      • Risk of pharming mitigation
                        • Anti-virus software to detect unauthorized altercations to a website address and warn the user of potential risks
                        • DNS server infected then difficult to mitigate
                        • Modern browsers can alert about pharming and phishing
                        • Check of the https green padlock sign.
      • Social Engineering
        • Relies on manipulating and deceiving people into providing confidential or personal data
        • Used for criminal activity
        • Take many different forms
        • Phishing is a form of social engineering
        • Quizzes online to take data
        • Data can be used against people
        • Target companies and individuals for data
        • Contact with the company and manipulation tried