This set covers the foundations of cyber security: the CIA triad, the difference between threats, vulnerabilities and risk, passive versus active attacks, denial of service, man-in-the-middle, phishing and social engineering, plus the security services and mechanisms defined in the OSI security architecture (X.800). It suits university semester exams, GATE and UGC NET aspirants revising network security, and candidates preparing for security-related placement and interview rounds.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 18 questions.
Topics covered in this set
- CIA triad and extended goals (authenticity, accountability)
- Threat, vulnerability, risk and exploit
- Passive vs active attacks
- DoS, DDoS and man-in-the-middle
- Phishing and social engineering
- X.800 security services and mechanisms
Cyber Security MCQs with answers and explanations
Q1. A hospital's patient database is altered by an unauthorised user who changes blood group entries. Which security goal is primarily violated?
a) Integrity
b) Confidentiality
c) Availability
d) Non-repudiation
Q2. Which of the following is a passive attack?
a) Replaying a captured login message
b) Traffic analysis of encrypted packets to infer who communicates with whom
c) Modifying a funds-transfer message in transit
d) Flooding a server with SYN packets
Q3. In risk terminology, a weakness in a system that could be exploited by a threat is called a:
a) Threat agent
b) Countermeasure
c) Vulnerability
d) Asset
Q4. Passive attacks are generally hard to detect. What is therefore the main defensive emphasis against them?
a) Detection and recovery
b) Rate limiting of traffic
c) Rebooting compromised hosts
d) Prevention, mainly through encryption
Q5. A DDoS attack differs from a basic DoS attack mainly because it:
a) Targets confidentiality rather than availability
b) Uses many distributed sources, often a botnet, to generate the attack traffic
c) Always exploits a software buffer overflow
d) Can be stopped by blocking a single source IP address
Q6. Which security service ensures that a sender cannot later deny having sent a message?
a) Non-repudiation
b) Access control
c) Data confidentiality
d) Traffic padding
Q7. An attacker positions themselves between a client and server, relaying and possibly altering messages while both parties believe they are talking directly. This is:
a) A brute-force attack
b) A dictionary attack
c) A side-channel attack
d) A man-in-the-middle attack
Q8. An employee receives an email that appears to come from the IT department asking them to 'verify' their password on a look-alike website. This is best classified as:
a) Tailgating
b) Shoulder surfing
c) Phishing
d) Dumpster diving
Q9. A targeted phishing email crafted specifically for a company's chief financial officer is called:
a) Whaling
b) Vishing
c) Smishing
d) Pharming
Q10. According to the X.800 OSI security architecture, which of the following is a security MECHANISM rather than a security SERVICE?
a) Authentication
b) Data integrity
c) Digital signature
d) Non-repudiation
Q11. A replay attack is best prevented by including which of the following in each authenticated message?
a) A longer encryption key
b) A nonce or timestamp checked for freshness
c) Compression of the payload
d) A larger packet size
Q12. Which property of the CIA triad is directly targeted by ransomware that encrypts files and demands payment, assuming no data is exfiltrated?
a) Confidentiality
b) Non-repudiation
c) Authenticity
d) Availability
Q13. Masquerade, as an active attack category, refers to:
a) Observing message lengths and frequency
b) Delaying or reordering messages
c) One entity pretending to be a different entity
d) Releasing message contents to a third party
Q14. A security team estimates a server is worth Rs 10,00,000, a particular threat would destroy 40% of its value, and the threat is expected 0.5 times a year. What is the Annualised Loss Expectancy (ALE)?
SLE = Asset value x Exposure factor ALE = SLE x ARO
a) Rs 4,00,000
b) Rs 5,00,000
c) Rs 20,000
d) Rs 2,00,000
Q15. The principle of 'least privilege' states that:
a) Users and processes should get only the minimum access needed for their task
b) All users should share a common administrator account
c) Access rights should increase with length of service
d) Security controls should be kept secret to be effective
Q16. Defence in depth is best described as:
a) Relying on one very strong perimeter firewall
b) Using multiple independent layers of security controls
c) Encrypting data twice with the same key
d) Hiding the network topology from users
Q17. A zero-day vulnerability is one that:
a) Has been patched for less than a day
b) Affects only systems with zero users
c) Cannot be exploited remotely
d) Is exploited before the vendor has released a fix or is aware of it
Q18. Which authentication combination is genuine multi-factor authentication?
a) A password plus a security question
b) A password plus a one-time code from a hardware token
c) Two different passwords
d) A PIN plus a memorised passphrase
Quick revision notes
- CIA triad: Confidentiality, Integrity, Availability; extended with authenticity and accountability.
- Risk = Threat x Vulnerability x Impact (conceptually); ALE = SLE x ARO, SLE = AV x EF.
- Passive attacks: release of message contents, traffic analysis - prevent with encryption.
- Active attacks: masquerade, replay, modification, denial of service - detect and recover.
- X.800 services: authentication, access control, confidentiality, integrity, non-repudiation (plus availability).
- X.800 mechanisms: encipherment, digital signature, access control, data integrity, authentication exchange, traffic padding, routing control, notarisation.
- Social engineering: phishing, spear phishing, whaling, vishing, smishing, pretexting, tailgating.
Frequently asked questions
What is the difference between a threat and a vulnerability?
A vulnerability is a weakness in a system, such as an unpatched service or weak password policy. A threat is a potential event or actor that could exploit that weakness to cause harm. Risk arises when a credible threat meets an exploitable vulnerability.
Why are passive attacks harder to detect than active attacks?
Passive attacks only observe traffic and do not modify data or disrupt service, so they leave little or no evidence. That is why encryption, which prevents disclosure in the first place, is the primary defence.
What are security services and mechanisms in X.800?
Services describe the protection offered, such as authentication, access control, confidentiality, integrity and non-repudiation. Mechanisms are the techniques that implement those services, such as encryption, digital signatures, traffic padding and notarisation.
Comments
Post a Comment