CompTIA A+: Security Concepts
Importance ★★★★★ · 28% (estimate)
Overview
This chapter covers how to keep people, devices, and data safe. It ranges from locks and badges to passwords, multifactor authentication, Wi-Fi security, malware, and social engineering. It is as large as the operating systems chapter on Core 2.
Strong security starts with who you are. Multifactor authentication (MFA) asks for two or more different kinds of proof: something you know (a password), something you have (a phone or token), or something you are (a fingerprint). The principle of least privilege means each user gets only the access needed for the job. For Wi-Fi, use WPA3 or WPA2 with AES, change default router passwords, and keep firmware up to date.
Malware comes in many forms. Ransomware encrypts files and demands payment, a trojan hides inside software that looks useful, a worm spreads by itself across networks, a keylogger records keystrokes, and a rootkit hides deep in the system. Social engineering tricks people instead of machines: phishing by email, vishing by phone, smishing by text, and tailgating by following someone through a secured door.
When removing malware, first confirm the symptoms, then quarantine the infected system from the network. In Windows, turn off System Restore so old restore points do not bring the infection back, then clean the system with updated tools, schedule scans and updates, turn System Restore back on with a fresh restore point, and teach the user how to avoid the problem.
Key concepts
MFA
Multifactor authentication: proof from two or more different factor types, such as a password plus a code from a phone app.
Memory tipTwo passwords are still one factor.
Least privilege
Give each user or program only the permissions it needs to do its job, and no more.
Memory tipUsers do daily work as standard users, not administrators.
Ransomware
Malware that encrypts a victim's files and demands payment for the key.
Memory tipGood offline backups are the best recovery plan.
Worm vs. virus
A virus attaches to files and spreads when they are run or shared. A worm spreads by itself across a network without user action.
Memory tipSpreads alone = worm.
Phishing family
Phishing uses fake emails, spear phishing targets one person, whaling targets executives, vishing uses voice calls, and smishing uses text messages.
Memory tipV = voice, S = SMS.
Tailgating
An unauthorized person follows an authorized person through a secure door.
Memory tipFix with an access control vestibule and staff training.
Often tested
- Use WPA3 when every device supports it; avoid WEP and WPA with TKIP.
- Disable System Restore during Windows malware removal so infected restore points are not reused.
- Change default administrator usernames and passwords on routers and other devices.
- Lock your screen (Windows key + L) whenever you leave your desk.
- An evil twin is a fake Wi-Fi access point that copies a real network's name.
3 sample questions
Verified practice questions from this unit.
Question 1. A user gets an email that looks like it is from their bank. It asks them to click a link and enter their password to "verify the account." What kind of attack is this?
- ① Phishing
- ② Shoulder surfing
- ③ Vishing
- ④ Tailgating
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Answer: ① Phishing
Key point: Phishing = fake email to steal information
Phishing uses fake emails or websites that look real to trick people into giving up passwords or other information. Banks do not ask you to confirm your password through an email link. When in doubt, go to the site by typing its address yourself.
Wrong choices
- Shoulder surfing: Shoulder surfing is watching someone's screen or keyboard to steal information.
- Vishing: Vishing is the same kind of trick done over a voice phone call, not email.
- Tailgating: Tailgating is following someone through a secure door, not sending an email.
Question 2. A user's files suddenly cannot be opened, and a message demands payment in cryptocurrency to unlock them. What type of malware is this?
- ① Ransomware
- ② Adware
- ③ Keylogger
- ④ Spyware
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Answer: ① Ransomware
Key point: Ransomware encrypts files and demands payment
Ransomware encrypts a victim's files and demands money for the key. The best protection is good backups kept separate from the network, along with updates and careful email habits.
Wrong choices
- Adware: Adware shows unwanted ads. It does not encrypt files.
- Keylogger: A keylogger records keystrokes. It does not lock files for ransom.
- Spyware: Spyware secretly watches and reports what a user does. It does not lock files and demand payment.
Question 3. Which wireless security setting gives the strongest protection on a new home or small office router?
- ① An open network with MAC filtering
- ② WPA3
- ③ WPA2 with TKIP
- ④ WEP
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Answer: ② WPA3
Key point: WPA3 is the strongest Wi-Fi security
WPA3 is the newest Wi-Fi security standard and gives the strongest protection. If an older device cannot use WPA3, WPA2 with AES is the next choice. WEP and TKIP are outdated and should not be used.
Wrong choices
- An open network with MAC filtering: An open network has no encryption, and MAC addresses are easy to copy.
- WPA2 with TKIP: WPA2 should use AES. TKIP is an older, weaker method.
- WEP: WEP is very old and can be cracked quickly.
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