CompTIA Security+ — All Questions

An attacker sends an email that appears to come from the company CEO, urgently asking the finance team to wire funds to a new vendor. What type of social engineering attack is this?

• a.Business email compromise✓
• b.Watering hole attack
• c.Tailgating
• d.Vishing

Business email compromise (BEC) impersonates a trusted executive or partner to trick employees into transferring money or sensitive data. It relies on authority and urgency rather than malware. Because it uses legitimate-looking email, it often bypasses technical filters and targets human judgment.

Which malware type encrypts a victim's files and demands payment for the decryption key?

• a.Ransomware✓
• b.Adware
• c.Keylogger
• d.Rootkit

Ransomware encrypts data and extorts the victim for a decryption key, often with a payment deadline. Modern variants also exfiltrate data first to enable double extortion. Reliable offline backups are the most effective recovery control.

A user reports that their credentials worked on a fake login page that looked identical to the corporate portal. Which attack most likely occurred?

• a.Buffer overflow
• b.SQL injection
• c.Privilege escalation
• d.Phishing✓

Phishing lures users to fraudulent pages that harvest credentials by mimicking legitimate sites. The cloned portal is the classic delivery mechanism. User training and multifactor authentication reduce the impact of harvested passwords.

Which term describes a previously unknown software vulnerability for which no patch yet exists?

• a.Zero-day✓
• b.Legacy flaw
• c.Race condition
• d.Misconfiguration

A zero-day is a vulnerability unknown to the vendor and defenders, giving zero days to prepare a fix. Attackers exploiting it face no available patch. Compensating controls like segmentation and behavior-based detection help mitigate the risk.

An attacker overwhelms a web server with traffic from thousands of compromised devices, making it unavailable. What is this called?

• a.Distributed denial-of-service✓
• b.On-path replay
• c.DNS poisoning
• d.Man-in-the-middle

A distributed denial-of-service (DDoS) attack floods a target from many compromised hosts, often a botnet, exhausting bandwidth or resources. The goal is to disrupt availability rather than steal data. Rate limiting, scrubbing services, and CDNs help absorb the load.

Which type of threat actor is typically well-funded, highly skilled, and motivated by espionage on behalf of a government?

• a.Hacktivist
• b.Script kiddie
• c.Insider by accident
• d.Nation-state actor✓

Nation-state actors, often labeled advanced persistent threats, have significant resources, patience, and sophisticated tooling. Their goals include espionage, sabotage, and strategic advantage. They frequently use zero-days and long-dwell stealthy campaigns.

A disgruntled employee copies confidential designs to a USB drive before resigning. This is an example of what threat?

• a.Shadow IT
• b.Watering hole
• c.Insider threat✓
• d.Supply chain attack

An insider threat comes from someone with authorized access who misuses it, whether maliciously or negligently. The employee here abuses legitimate access to steal data. Data loss prevention, least privilege, and monitoring help detect such activity.

Which attack injects malicious database commands through unvalidated user input fields?

• a.Directory traversal
• b.SQL injection✓
• c.Session hijacking
• d.Cross-site scripting

SQL injection inserts crafted database statements through input that the application fails to sanitize. It can expose, modify, or delete data. Parameterized queries and input validation are the primary defenses.

An attacker leaves infected USB drives in a company parking lot hoping employees will plug them in. This technique is known as:

• a.Whaling
• b.Baiting✓
• c.Shoulder surfing
• d.Pretexting

Baiting entices victims with something appealing, such as a found USB drive, to trigger a compromise. Curiosity leads the victim to introduce the malware themselves. Endpoint controls that block unknown removable media reduce this risk.

Which malware disguises itself as legitimate software but performs malicious actions once installed?

• a.Logic bomb
• b.Botnet
• c.Worm
• d.Trojan✓

A Trojan masquerades as a benign or useful program to trick users into running it. Unlike a worm, it does not self-replicate; it relies on deception. Once executed it may open backdoors, steal data, or download further payloads.

A malicious program spreads across a network automatically without any user interaction. What is it?

• a.Spyware
• b.Trojan
• c.Worm✓
• d.Rootkit

A worm self-replicates and propagates across networks by exploiting vulnerabilities, requiring no user action. This makes outbreaks spread rapidly. Timely patching and network segmentation slow worm propagation.

An attacker calls an employee pretending to be IT support to trick them into revealing a password. This voice-based social engineering is called:

• a.Phishing
• b.Spooling
• c.Smishing
• d.Vishing✓

Vishing uses voice calls to manipulate victims into disclosing information or performing actions. The attacker builds a plausible pretext, often posing as a trusted party. Verification callbacks and never sharing passwords by phone are effective countermeasures.

Which attack compromises a website frequently visited by a target group to infect their systems?

• a.Rainbow table
• b.Typosquatting
• c.Pass-the-hash
• d.Watering hole✓

A watering hole attack infects a site the intended victims commonly use, so visiting it delivers malware. It targets a community indirectly through a trusted resource. Keeping browsers patched and using endpoint protection reduces exposure.

Which term describes a hidden vulnerability in a third-party component that compromises everyone who uses it?

• a.Configuration drift
• b.Insider risk
• c.Physical risk
• d.Supply chain risk✓

Supply chain risk arises when a trusted vendor, library, or hardware component is compromised, affecting downstream customers. A single tainted update can reach many organizations. Vendor assessments and software bill of materials help manage this risk.

Malware that records every keystroke a user types to capture passwords is a:

• a.Keylogger✓
• b.Rootkit
• c.Backdoor
• d.Ransomware

A keylogger captures keyboard input to steal credentials, messages, and other sensitive typed data. It can be software or hardware based. Multifactor authentication limits the damage from stolen static passwords.

An attacker registers a domain like 'goggle.com' hoping users mistype the real address. This is:

• a.DNS spoofing
• b.Typosquatting✓
• c.Pharming
• d.Session fixation

Typosquatting registers look-alike domains based on common misspellings to catch mistyped traffic. Victims may land on malicious or fraudulent pages. Users should verify URLs and organizations can defensively register close variants.

Which type of malware hides deep in the operating system to conceal its presence and maintain privileged access?

• a.Worm
• b.Adware
• c.Trojan
• d.Rootkit✓

A rootkit embeds itself at a low level, often the kernel, to hide processes and files while retaining elevated control. Its stealth makes detection and removal difficult. Secure boot and integrity monitoring help defend against rootkits.

A phishing attack that specifically targets a high-value executive is known as:

• a.Spear tailoring
• b.Vishing
• c.Whaling✓
• d.Smishing

Whaling is a form of spear phishing aimed at senior executives or high-profile targets. The lures are carefully crafted for that individual and their authority. Executive awareness training and verification procedures reduce success.

Which attack intercepts and possibly alters communication between two parties who believe they are talking directly?

• a.On-path (man-in-the-middle)✓
• b.Cross-site request forgery
• c.Brute force
• d.Denial-of-service

An on-path attack, historically called man-in-the-middle, positions the attacker between two endpoints to eavesdrop or tamper with traffic. Unencrypted channels are especially vulnerable. Strong encryption and certificate validation mitigate it.

A malicious script stored on a vulnerable web page runs in other users' browsers when they view it. This is:

• a.Stored cross-site scripting✓
• b.Clickjacking
• c.SQL injection
• d.CSRF

Stored cross-site scripting (XSS) persists malicious script on the server so it executes in every visitor's browser. It can steal session tokens or perform actions as the victim. Output encoding and input validation prevent XSS.

Which term describes exploiting a time gap between checking a resource and using it?

• a.Replay attack
• b.Race condition✓
• c.Buffer overflow
• d.Injection

A race condition, or time-of-check to time-of-use flaw, exploits the interval between validating and using a resource. An attacker changes state in that window to bypass controls. Proper locking and atomic operations prevent it.

An attacker follows an employee through a secured door without badging in. This physical attack is called:

• a.Piggyback encryption
• b.Tailgating✓
• c.Shoulder surfing
• d.Dumpster diving

Tailgating is entering a restricted area by closely following an authorized person through a controlled door. It exploits politeness and weak physical enforcement. Mantraps, turnstiles, and awareness reduce tailgating.

Which attack precomputes hashes to reverse password hashes quickly?

• a.Rainbow table attack✓
• b.Dictionary attack
• c.Credential stuffing
• d.Password spraying

A rainbow table uses precomputed hash chains to reverse unsalted password hashes efficiently. Adding a unique random salt to each password defeats this approach. Modern slow hashing functions further increase cracking cost.

An attacker tries a few very common passwords across many user accounts to avoid lockouts. This is:

• a.Brute force
• b.Pass-the-hash
• c.Rainbow table
• d.Password spraying✓

Password spraying tests a small set of common passwords across many accounts, staying under lockout thresholds. It exploits weak, reused passwords at scale. Strong password policies, MFA, and anomaly detection counter it.

Which security model assumes no user or device is trusted by default, even inside the network perimeter?

• a.Zero trust✓
• b.Perimeter security
• c.Implicit trust
• d.Defense in depth

Zero trust removes automatic trust based on network location and continuously verifies every request. Access is granted per session based on identity, device posture, and context. It reduces lateral movement after a breach.

Layering multiple independent security controls so that one failure does not cause a breach is called:

• a.Air gapping
• b.Single sign-on
• c.Defense in depth✓
• d.Least privilege

Defense in depth stacks overlapping controls across people, process, and technology so no single failure is catastrophic. If one layer is bypassed, others still protect the asset. It reflects the assumption that any one control can fail.

Dividing a network into isolated zones to limit the spread of an attack is known as:

• a.Tunneling
• b.Segmentation✓
• c.Load balancing
• d.Port forwarding

Network segmentation separates systems into zones so a compromise in one cannot freely reach others. It limits lateral movement and contains breaches. VLANs, firewalls, and microsegmentation implement this principle.

Which network area sits between the internet and the internal network to host public-facing services?

• a.Screened subnet (DMZ)✓
• b.VPN concentrator
• c.Air gap
• d.Intranet

A screened subnet, historically called a DMZ, isolates public-facing servers from the internal network. If a public host is compromised, the internal network remains protected by an additional boundary. Firewalls control traffic on both sides.

Which cloud model gives the customer the most control over the operating system and applications while the provider manages the physical hardware?

• a.Software as a Service
• b.Platform as a Service
• c.Function as a Service
• d.Infrastructure as a Service✓

Infrastructure as a Service (IaaS) provides virtualized compute, storage, and networking while the customer manages the OS and applications. This maximizes customer control and responsibility. SaaS, by contrast, hands nearly everything to the provider.

In cloud computing, which concept defines who is responsible for securing which layers of the stack?

• a.Multitenancy
• b.Serverless
• c.Elasticity
• d.Shared responsibility model✓

The shared responsibility model divides security duties between the cloud provider and the customer. The provider secures the underlying infrastructure while the customer secures data, identities, and configurations. Misunderstanding the split is a common source of cloud breaches.

Which technology allows multiple isolated operating systems to run on a single physical host?

• a.Containerization
• b.Clustering
• c.Virtualization✓
• d.Load balancing

Virtualization uses a hypervisor to run multiple guest operating systems on one physical machine, each isolated in a virtual machine. It improves resource use and isolation. Hardening the hypervisor is critical because it is a high-value target.

Which approach packages an application with its dependencies to run consistently across environments while sharing the host OS kernel?

• a.Bare-metal deployment
• b.Full virtualization
• c.Containerization✓
• d.Air gapping

Containerization bundles an application and its dependencies into a lightweight, portable unit that shares the host kernel. Containers start quickly and use fewer resources than full VMs. Isolation is weaker than VMs, so kernel and image security matter.

Which principle grants users only the minimum access needed to perform their job?

• a.Least privilege✓
• b.Implicit deny
• c.Separation of duties
• d.Defense in depth

Least privilege limits each user or process to only the permissions required for its role. This shrinks the attack surface and limits damage from compromised accounts. Regular access reviews keep privileges aligned with need.

A firewall rule set ends with a rule that blocks anything not explicitly permitted. This is called:

• a.Explicit allow
• b.Implicit deny✓
• c.Stateful inspection
• d.Failover

Implicit deny blocks all traffic that no earlier rule explicitly allows. It ensures only intended traffic passes and unknowns are rejected by default. This deny-by-default posture is a core secure design principle.

Which design ensures a system has no single point of failure by duplicating critical components?

• a.Segmentation
• b.Redundancy✓
• c.Least functionality
• d.Tokenization

Redundancy duplicates critical components, such as power supplies or servers, so failure of one does not cause an outage. It supports high availability and resilience. Combined with failover, it keeps services running through faults.

Which term describes an isolated environment where suspicious code can be executed and analyzed safely?

• a.Sandbox✓
• b.Honeypot
• c.Bastion host
• d.Air gap

A sandbox is a contained, isolated environment for running untrusted code without risking the host or network. It is used to analyze malware behavior or test software safely. Escapes from the sandbox are a key security concern.

Which decoy system is deployed to attract attackers and study their techniques?

• a.Proxy server
• b.Load balancer
• c.Honeypot✓
• d.Jump server

A honeypot is a deliberately vulnerable-looking decoy that lures attackers away from real assets and gathers intelligence on their methods. Any interaction with it is suspicious by design. Honeynets extend the concept to entire fake networks.

Which hardened intermediary host is used to securely administer devices in a sensitive network segment?

• a.Web proxy
• b.Honeypot
• c.Jump server (bastion host)✓
• d.DNS resolver

A jump server, or bastion host, is a tightly controlled system that administrators connect through to reach protected segments. It centralizes and monitors administrative access. Hardening and logging on this host are essential because it is a gateway to sensitive systems.

Which control physically separates a highly sensitive network from all other networks and the internet?

• a.Air gap✓
• b.Screened subnet
• c.NAT
• d.VPN

An air gap isolates a system or network so it has no physical or logical connection to untrusted networks. It is used for critical systems like industrial controls. Data transfer requires manual, controlled processes, which reduces remote attack surface.

Which concept keeps availability high by automatically shifting workloads to a standby system when the primary fails?

• a.Segmentation
• b.Failover✓
• c.Load balancing
• d.Snapshotting

Failover automatically transfers operations to a redundant standby when the active component fails, minimizing downtime. It is a cornerstone of high-availability design. Regular testing ensures the standby will actually take over when needed.

Embedded systems in industrial equipment that monitor and control physical processes are collectively known as:

• a.IoT hubs
• b.ICS/SCADA✓
• c.Edge routers
• d.Thin clients

Industrial control systems (ICS), including SCADA, manage physical processes in utilities and manufacturing. They often run legacy software and prioritize availability over patching. Segmentation and strict access control are key because downtime and safety are critical.

Which design principle removes unnecessary services, ports, and software to reduce a system's attack surface?

• a.Least functionality✓
• b.Elasticity
• c.Multitenancy
• d.Redundancy

Least functionality configures a system to run only the services and features required for its purpose. Disabling unneeded components shrinks the attack surface. It complements least privilege by hardening the system itself, not just user access.

Which type of encryption uses the same key to encrypt and decrypt data?

• a.Asymmetric
• b.Hashing
• c.Symmetric✓
• d.Steganographic

Symmetric encryption uses a single shared secret key for both encryption and decryption, such as AES. It is fast and suited to bulk data. The main challenge is securely distributing the shared key.

Which cryptographic method uses a public and private key pair?

• a.Asymmetric encryption✓
• b.Salting
• c.Hashing
• d.Symmetric encryption

Asymmetric encryption uses a mathematically linked key pair: a public key to encrypt and a private key to decrypt, or the reverse for signatures. It solves the key distribution problem of symmetric systems. RSA and elliptic curve are common examples.

Which one-way function produces a fixed-length value that cannot be reversed to the original input?

• a.Steganography
• b.Symmetric cipher
• c.Hashing✓
• d.Tokenization

Hashing transforms input into a fixed-length digest that cannot be feasibly reversed. It verifies integrity because any change to the input changes the hash. SHA-256 is a widely used secure hashing algorithm.

Adding a unique random value to each password before hashing to defeat precomputed attacks is called:

• a.Salting✓
• b.Peppering
• c.Stretching
• d.Encoding

Salting prepends or appends a unique random value to each password before hashing. This ensures identical passwords produce different hashes and defeats rainbow tables. Each salt must be unique and stored alongside the hash.

Which entity in a PKI issues and signs digital certificates?

• a.Key escrow agent
• b.Certificate authority✓
• c.Registration authority
• d.Certificate holder

A certificate authority (CA) issues, signs, and vouches for digital certificates, binding a public key to an identity. Trust in the CA underpins the entire PKI. A compromised CA can undermine trust for all certificates it issued.

Which mechanism lets a client quickly check whether a single certificate has been revoked?

• a.Certificate pinning
• b.Key stretching
• c.Online Certificate Status Protocol✓
• d.Certificate signing request

The Online Certificate Status Protocol (OCSP) queries a responder in real time to check a certificate's revocation status. It is faster and more current than downloading a full certificate revocation list. OCSP stapling improves performance and privacy.

What does a digital signature primarily provide?

• a.Integrity and non-repudiation✓
• b.Availability
• c.Faster encryption
• d.Confidentiality only

A digital signature proves the message came from the holder of the private key and was not altered, giving integrity, authentication, and non-repudiation. It does not by itself keep the content secret. It is created by encrypting a hash with the signer's private key.

Which authentication factor category does a fingerprint belong to?

• a.Something you are✓
• b.Something you know
• c.Something you have
• d.Somewhere you are

A fingerprint is a biometric, which is the 'something you are' factor based on physical characteristics. Combining it with a different factor, such as a password, creates multifactor authentication. Biometrics resist sharing but raise privacy and revocation concerns.