Cybersecurity Glossary: A-Z Terms Explained
Core vocabulary referenced across our tool tutorials — from Nmap and Metasploit to Hydra and Burp Suite — explained in plain English.
A
- Attack Surface
- All the possible points where an unauthorized user could try to enter or extract data from a system.
- Authentication
- The process of verifying that someone is who they claim to be, typically through a password, token, or biometric.
- Authorization
- The process of determining what an authenticated user is allowed to do or access.
B
- Brute Force Attack
- Systematically trying every possible password combination until the correct one is found. See our Hydra tutorial.
- Backdoor
- A hidden method of bypassing normal authentication to gain access to a system.
C
- CVE (Common Vulnerabilities and Exposures)
- A publicly cataloged, unique identifier assigned to a specific known security vulnerability.
- Credential Stuffing
- Using username/password pairs stolen from one breach to attempt logins on unrelated websites, relying on password reuse.
- CTF (Capture The Flag)
- A cybersecurity competition format where participants solve challenges to find hidden "flags."
D
- Dictionary Attack
- A password-cracking method that tries words from a precompiled list rather than every possible combination. See our John the Ripper tutorial.
- DDoS (Distributed Denial of Service)
- An attack that floods a system with traffic from many sources to make it unavailable to legitimate users.
E
- Encryption
- Converting readable data into a coded form that can only be read again with the correct decryption key.
- Exploit
- Code or a technique that takes advantage of a specific vulnerability to cause unintended behavior. See our Metasploit tutorial.
F
- Firewall
- A network security system that monitors and controls incoming and outgoing traffic based on defined rules.
G
- Gray Hat
- A hacker who operates in an ethical gray area — probing systems without explicit authorization but without malicious intent, often disclosing findings afterward.
H
- Hash
- A fixed-length string generated from data using a mathematical function; used to store passwords securely without saving the actual text. See our Hashcat tutorial.
- Hardening
- Reducing a system's attack surface by disabling unnecessary services, applying patches, and tightening configurations.
I
- IDS/IPS (Intrusion Detection/Prevention System)
- A tool that monitors network traffic for suspicious activity and either alerts (IDS) or actively blocks (IPS) potential threats.
- Incident Response
- The organized process of detecting, investigating, containing, and recovering from a security breach.
J
- JWT (JSON Web Token)
- A compact, signed token format commonly used to authenticate users and pass session data between a client and a server.
K
- Keylogger
- Malware or hardware that secretly records keystrokes, often used to steal passwords and other sensitive input.
L
- Lateral Movement
- Techniques attackers use to move through a network after an initial breach, expanding access to other systems.
- Least Privilege
- A security principle where users and systems are granted only the minimum access necessary to do their job.
M
- Malware
- Software designed to cause damage, steal data, or gain unauthorized access — covering viruses, ransomware, spyware, and more.
- MFA (Multi-Factor Authentication)
- A security method requiring two or more independent forms of verification before granting access.
N
- NIST
- The U.S. National Institute of Standards and Technology, which publishes widely referenced cybersecurity frameworks and password guidelines.
O
- OSINT (Open-Source Intelligence)
- Gathering information from publicly available sources — websites, social media, public records — to support security research or an authorized assessment.
P
- Payload
- The part of an exploit that actually executes on a target after successful exploitation. See our Metasploit tutorial.
- Penetration Testing
- An authorized, simulated attack on a system to evaluate its security and find exploitable weaknesses.
- Phishing
- A social engineering attack where a fake message or website tricks someone into revealing sensitive information.
- Port
- A numbered communication endpoint used by network services. See our Nmap tutorial.
Q
- Quarantine
- Isolating a suspicious or infected file so it can no longer run or spread, without immediately deleting it.
R
- Ransomware
- Malware that encrypts a victim's files and demands payment for the decryption key.
- Red Team
- A group that simulates real-world attacker behavior to test an organization's detection and response.
S
- Social Engineering
- Manipulating people, rather than technical systems, into giving up confidential information.
- SOC (Security Operations Center)
- A team responsible for continuously monitoring, detecting, and responding to security incidents. See our SOC Analyst career guide.
- SQL Injection
- Inserting malicious SQL code into input fields to manipulate or extract data from a database.
T
- Threat Actor
- An individual or group responsible for carrying out — or attempting to carry out — a malicious act against a system or network.
- Trojan
- Malware disguised as legitimate software to trick a user into installing it.
- Two-Factor Authentication (2FA)
- A specific form of MFA requiring exactly two independent forms of verification, such as a password and a one-time code.
U
- User Enumeration
- Probing a system to determine whether specific usernames or accounts exist, often a precursor to a targeted brute-force attack.
V
- Vulnerability
- A weakness in a system that could potentially be exploited.
- VPN (Virtual Private Network)
- A service that creates an encrypted connection over a network, often used to protect traffic or mask an IP address. See our NordVPN review.
W
- WAF (Web Application Firewall)
- A firewall that filters, monitors, and blocks malicious HTTP traffic to and from a web application.
- Wordlist
- A list of candidate passwords or usernames used in dictionary and brute-force attacks. See our Hydra and John the Ripper tutorials.
X
- XSS (Cross-Site Scripting)
- An injection attack where malicious scripts are inserted into otherwise trusted websites and executed in another user's browser. See our Burp Suite and OWASP ZAP tutorials.
Y
- YARA Rule
- A pattern-matching rule used to identify and classify malware samples based on textual or binary patterns.
Z
- Zero-Day
- A vulnerability unknown to the vendor with no available patch — defenders have had "zero days" to fix it before exploitation.