Cybersecurity Glossary

A skilled, well-resourced attacker, often state-linked, that stays hidden in a network for a long time to steal data or spy.

Everything an attacker could target: internet-facing services, devices, accounts, software and people.

A hidden way into a system that bypasses normal authentication, planted by an attacker or left by mistake.

A network of infected devices remotely controlled by an attacker, often used for spam or DDoS attacks.

Guessing passwords or keys by trying huge numbers of combinations automatically.

An organisation trusted to issue the digital certificates that prove a website's identity (the padlock in your browser).

The US Cybersecurity and Infrastructure Security Agency's catalogue of vulnerabilities confirmed to be exploited in the wild.

Using usernames and passwords leaked from one site to break into accounts on other sites.

Common Vulnerabilities and Exposures: a unique public ID for a specific security flaw, such as CVE-2026-110264.

Common Vulnerability Scoring System: a 0–10 rating of a flaw's technical severity.

Common Weakness Enumeration: a catalogue of software mistake types, such as CWE-79 cross-site scripting.

Distributed denial of service: overwhelming a website or network with traffic from many sources to knock it offline.

AI-generated audio, image or video that convincingly imitates a real person.

Endpoint detection and response: software that monitors computers for malicious behaviour and helps respond to it.

Scrambling data so only someone with the right key can read it.

Exploit Prediction Scoring System: estimates the probability a vulnerability will be exploited in the next 30 days.

Code or a technique that takes advantage of a vulnerability.

A control that allows or blocks network traffic based on rules.

The organised process of detecting, containing, investigating and recovering from a security incident.

Evidence that a system may have been breached, such as a malicious IP address, domain or file hash.

Malware that harvests passwords, browser cookies, crypto wallets and other credentials.

An attacker moving from the first compromised machine to others inside the network.

Malicious software, including viruses, worms, trojans, ransomware and spyware.

Requiring a second proof of identity, such as an app code or passkey, in addition to a password.

A phishing-resistant replacement for passwords, using cryptographic keys stored on your device.

An update that fixes a bug or vulnerability.

An authorised, simulated attack to find weaknesses before real attackers do.

Fraudulent messages that trick people into revealing information, paying money or installing malware.

Gaining higher permissions than intended, for example from a normal user to administrator.

Malware that encrypts or steals data and demands payment for its return or for silence.

A flaw that lets an attacker run their own code on a target system from a distance.

An isolated environment for running untrusted code or files safely.

Security information and event management: a platform that collects and analyses logs to detect threats.

Phishing by SMS text message.

Security operations centre: the team that monitors and responds to security events.

Manipulating people, rather than technology, to gain access or information.

Compromising a trusted supplier, software package or update to reach that supplier's customers.

Evidence-based knowledge about attackers, their tools and their behaviour, used to improve defences.

Flooding a user with login approval prompts until they accept one by mistake.

Voice phishing: scams carried out by phone call, increasingly with AI-cloned voices.

Virtual private network: an encrypted tunnel for network traffic.

A weakness in software, hardware or process that an attacker could exploit.

Web application firewall: filters malicious web traffic before it reaches an application.

A security model that never assumes trust based on network location, and verifies every user and device every time.

A vulnerability that attackers know about before a fix is available.