Malware

Malware (malicious software) is any program written to harm or gain unauthorised access to a computer system. AQA expects you to know the common types:

• Virus — attaches itself to a file; runs and spreads when that file is opened.
• Worm — self-replicating malware that spreads across a network on its own, without needing a host file.
• Trojan — disguised as a legitimate, useful program; once run it lets attackers in.
• Spyware — secretly records what you do (e.g. keystrokes) and sends it to an attacker.
• Ransomware — encrypts (locks) your files and demands a payment to unlock them.

Definition to memorise: malware is malicious software designed to damage, disrupt or gain unauthorised access to a computer or its data.

Name that threat

Social engineering — the human weakness

Social engineering means manipulating people into giving away information or access, rather than attacking the technology directly. People are often the weakest link in security. Common forms:

• Phishing — fake emails or messages pretending to be from a trusted source (a bank, a boss) to steal login details or money.
• Blagging (pretexting) — inventing a convincing scenario (a "pretext") to persuade someone to hand over information, e.g. phoning and pretending to be IT support.
• Shouldering (shoulder surfing) — watching over someone's shoulder as they type a PIN or password.

Key idea: social engineering attacks the person, not the machine — which is why staff training is a vital defence.

SQL injection, brute force & denial of service

Beyond malware and social engineering, AQA lists several technical attacks:

• SQL injection — typing SQL code into a website's input box (like a login field) to attack, read or damage the database behind it.
• Brute force attack — trying huge numbers of password combinations until one works.
• Denial of service (DoS / DDoS) — flooding a server with so many requests that it can't respond to legitimate users.
• Data interception and theft — capturing data as it travels across a network (e.g. on unsecured Wi-Fi).
• Poor network policy — weak rules (e.g. no password rules, no updates) that leave a system open to attack.

Preventing SQL injection: use input validation and parameterised queries so user input can't be run as SQL commands.

Your turn — brute force

Firewalls

A firewall controls the traffic coming in and out of a network according to a set of rules. It sits between the network and the outside world, blocking anything that doesn't meet the rules.

Remember: a firewall filters traffic by rules — it does not remove viruses already on a machine (that's anti-malware's job).

Encryption

Encryption scrambles data using a key so that anyone who intercepts it sees only meaningless text. Only someone with the correct key can decrypt (unscramble) it back into readable form.

Key point: encryption doesn't stop data being intercepted — it makes intercepted data useless to the attacker.

What does encryption do?

Your turn — password strength

Authentication & user access levels

Authentication means confirming that a user really is who they claim to be before granting access. AQA covers several methods:

• Passwords — kept strong with a password policy (minimum length, mix of letters/numbers/symbols).
• Biometrics — using a fingerprint, face or iris to confirm identity.
• Two-factor authentication (2FA) — needing a second proof, e.g. a code texted to your phone as well as your password.
• User access levels / permissions — giving each user only the access they need, so a low-level account can't reach sensitive data.

Strong passwords: longer passwords with a wider mix of characters have far more combinations, making brute force attacks much slower to succeed.

Name the attack

Anti-malware, MAC filtering & penetration testing

More defences AQA expects you to know:

• Anti-malware software — scans for and removes viruses and other malware, and blocks known threats.
• MAC address filtering — only lets devices with approved hardware (MAC) addresses join the network.
• Penetration testing — deliberately testing a system's security (attacking your own system) to find vulnerabilities before real attackers do, so they can be fixed.

Layered defence: no single method is enough — real systems combine firewalls, encryption, authentication, anti-malware and testing.

Threat or protection?

Tap an item, then tap the box it belongs to.

Match term to meaning

Tap a description on the left, then its matching term on the right.

Test yourself first

The big ideas to know

You've covered all of AQA 3.6 — the main threats and the ways to protect systems and data. Press Finish to see your score.