SS 3 First Term

Learning Objectives

• Describe common cyber threats and how to reduce them.
• Explain the main methods of keeping data secure.
• Describe emerging digital technologies and their uses.
• Discuss the benefits and risks of the technologies.

The Parts of Computer Security

Computer security is made of three parts. Confidentiality means that information is available only to those allowed to see it. Integrity means that it is complete and has not been altered without permission. Availability means that it is there when it is needed.

A threat to any of these three can cause harm. A virus that deletes records harms availability and integrity. A password stolen from a bank account harms confidentiality. These three parts give the vocabulary used to describe any security measure and any security failure.

Threats to Computer Security

A virus is a program written to damage a computer or its data. A worm spreads across a network by itself. A trojan looks useful but carries a harmful part. Spyware collects information without the user knowing. Ransomware locks files and demands a payment. A worm needs no user action, which makes it the fastest spreading of the group.

A phishing message tricks a user into giving away details such as a password. A password attack guesses or steals a password. A denial of service attack floods a system so that it cannot be used by anyone. Identity theft happens when another person uses stolen details to impersonate the owner.

Human error is also a threat. A password written on a card kept in a drawer, a file left open on a shared computer and a memory card left in a computer are all ways for data to reach the wrong person without any attack at all.

Protecting the Computer

An antivirus program checks files and removes harmful programs. It must be kept up to date, because new programs appear every day. A firewall controls the connections into and out of a computer and blocks those that are not wanted. A firewall set too tightly blocks legitimate work, so it is configured carefully.

A strong password is at least eight characters long and mixes letters, numbers and symbols. A different password is used for each important account, so that one breach does not open several. A password manager stores many strong passwords safely so that they do not have to be memorised.

Software is updated because the updates repair faults that attackers use. An operating system or program that is no longer supported will be attacked successfully at some point, so a device that cannot be updated should be replaced.

Data is protected by making a backup on a separate device and by keeping a copy away from the machine. A backup on the same computer is not a backup, because the same fault removes both.

An antivirus program that is not updated quickly will miss new programs, so the update schedule matters as much as the software.

A firewall set too tightly blocks legitimate work, so security and usability must be balanced.

A backup stored on the same computer is not a backup, because one fault removes both copies.

Security in a School Laboratory

Every user should have an account, so that the work of each person is separate and can be traced. A user who must sit at the same computer every lesson should log off when finished rather than leaving the account open.

Files belonging to the school are kept on a server with a backup, and the access to that folder is given only to staff who need it. Memory cards and hard drives used for transfer are scanned before they are used again.

Physical security matters as much as software security. The door of the laboratory should be locked when the room is not in use, and screens should be positioned so that they cannot be seen from outside. Cables should be secured so that they cannot be pulled out.

Responding to an Incident

When something goes wrong the steps are the same. Disconnect the computer from the network so that the problem does not spread. Report it to the teacher or the administrator. Write down what happened and when, because the details are lost quickly.

A file that has been encrypted by ransomware is not made usable by paying quietly. The machine is left as it is so that it can be examined, and the backups are checked so that the data can be restored.

After an incident the cause is established and the measure that would have prevented it is added. Without that last step the same incident happens again.

Paying a ransomware demand does not guarantee that the files are released, so the machine is left for examination.

Artificial Intelligence and Machine Learning

Artificial intelligence is the making of systems that can do tasks which normally need human thought, such as recognising a face, translating a language or deciding which message is a spam. Most of these systems are built for one narrow task rather than for general intelligence.

Machine learning is the method used to build such a system. Data is collected, a model is trained on that data, and the trained model is then asked to predict or to classify something it has not seen. The quality of the result depends on the quality and the quantity of the data used.

The model learns a pattern rather than a rule written by a person. A program that decides a loan must not learn from past decisions that were unfair, because the model copies the pattern it was given, including a wrong one.

Artificial intelligence is used in medicine to read scan images, in agriculture to predict crop yield, in transport to adjust traffic signals, in banking to spot fraud and in a keyboard to suggest the next word.

Blockchain

A blockchain is a list of records stored across many computers. Each record is placed in a block, and each block holds a code made from the data in the block and the code of the block before it. Changing any earlier record changes every code after it, so the change is visible.

The blocks are held by many computers called nodes, and they agree on the record by a method called a consensus. No single person or company holds the whole list, and no single record can be removed without the change being noticed by the other nodes.

A blockchain is therefore useful where several organisations need one trusted shared record and no one of them should be able to alter it alone. The uses include tracking goods through a supply chain, recording land titles, and keeping a tamper evident record of a transaction.

The cost of a blockchain is that every node keeps a copy, so the data is held many times, and the agreement takes time. It is not the right tool for ordinary school records.

Other Emerging Technologies

The internet of things describes ordinary objects that are fitted with sensors and connected to a network, so that they can be monitored or controlled from a distance. Examples include a watch that counts steps, a meter that reports its own reading, and a door that can be opened without a key.

Cloud computing keeps files and software on servers reached through the internet rather than on the computer itself, so a file can be opened on any device. It also allows several people to work on the same file at the same time.

Benefits and Risks

The benefits are speed, reach and accuracy. A diagnostic result can be available in minutes instead of days, a farmer can water a field only where it is dry, and a language model can support a speaker of a language with few speakers.

The risks are loss of privacy, unfair decisions and concentration of power. A system trained on past decisions may reproduce past discrimination, and a system that collects large amounts of personal data creates a target for theft. A technology that is used without supervision can be used to mislead as easily as to help.

The response is control. Data collection should be limited to what is needed, a trained model should be tested on data it has not seen, and a decision made by a system should be checked by a named person who can explain it. New technology should be measured against these controls rather than adopted because it is new.

Practical Work

1. List four cyber threats and one defence against each.
2. Explain why regular backups matter.
3. Describe two uses of artificial intelligence.
4. State one benefit and one risk of one emerging technology.

Scenario-Based Questions

1. An office suffers a ransomware attack. Explain the steps to respond.
2. Explain why staff training is part of cyber security.
3. Explain how artificial intelligence can help a small business.
4. Explain one risk that a new technology can bring to privacy.