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

Step 1: Analyzing the SFTP Log

The SFTP log provides a record of file transfer and login activities:

User “sjames” logged in from several IP addresses:

192.168.10.32 and 192.168.10.37 (internal network IPs)

32.111.16.37 and 41.21.18.102 (external IPs)

We see file alterations in the /var/www directory, which is commonly the web directory.

Modified files: about_us.html, index.html

Suspicious activity:

192.168.11.102 and 41.21.18.102 modified the files.

32.111.16.37 had failed login attempts, indicating possible unauthorized access attempts.

The most suspicious IP here is 41.21.18.102, as it’s associated with direct file modifications, possibly indicating unauthorized access.

Step 2: Reviewing Netstat

The netstat output shows active connections and their states:

IP 41.21.18.102 has an ESTABLISHED connection with port 22, commonly used for SFTP.

IP 32.111.16.37 is also attempting connections, and 32.111.16.37 connections are in a TIME_WAIT state, showing prior connections were recently closed.

The netstat output reaffirms 41.21.18.102 is actively connected and potentially involved in malicious activities.

Step 3: Checking the HTTP Access Log

The HTTP Access log shows access to about_us.html:

32.111.16.37 repeatedly accessed /about_us.html with 404 errors, indicating attempts to reach non-existing pages.

41.21.18.102 accessed the 200 status code, showing successful page requests, but since this IP was modifying files directly on the server, it might be testing or verifying changes.

Again, 41.21.18.102 stands out as it matches both successful file modification and page request patterns, while 32.111.16.37 shows unsuccessful attempts.

Step 4: Selecting the IP of Concern

Based on the above analysis:

Answer: 41.21.18.102 should be the IP of concern due to its direct file modifications on critical web files (about_us.html, index.html).

Step 5: Identifying the Indicator of Compromise

Potential indicators include unauthorized file modifications:

Modified index.html file is the correct answer, as it indicates direct changes to website content and is often a clear sign of compromise.

Step 6: Selecting Corrective Actions

To mitigate and prevent further compromise:

Change the password on the “sjames” account: The account was used across various IPs, indicating potential account compromise.

Block external SFTP access: Restricting SFTP to internal IPs only would prevent unauthorized external modifications. Since 41.21.18.102 was external, this would stop similar threats.

Summary

IP of Concern: 41.21.18.102

Indicator of Compromise: Modified index.html file

Corrective Actions:

Change the password on the sjames account

Block external SFTP access

These selections address both the immediate security breach and implement a preventative measure against future unauthorized access.

The system that should be prioritized for patching first is 54.74.110.228, as it has the highest number and severity of vulnerabilities among the four systems listed in the vulnerability report. According to the report, this system has 12 vulnerabilities, with 8 critical, 3 high, and 1 medium severity ratings. Thecritical vulnerabilities include CVE-2019-0708 (BlueKeep), CVE-2019-1182 (DejaBlue), CVE-2017-0144 (EternalBlue), and CVE-2017-0145 (EternalRomance), which are all remote code execution vulnerabilities that can allow an attacker to compromise the system without any user interaction or authentication. These vulnerabilities pose a high risk to the system and should be patched as soon as possible.

Thechain of custodyis a documented history that tracks how evidence is handled, collected, transported, and preserved at every stage of the forensic investigation. If a gap exists in the record of who transferred or accessed the evidence, it could call into question the integrity and admissibility of the evidence​.

Validating data integrity (Option A)refers to ensuring that the forensic image is identical to the original data, often using cryptographic hashing, but it does not address procedural gaps in documentation.

Preservation (Option B)involves protecting the original evidence from modification or loss but does not include logging transfers of custody.

Legal hold (Option C)refers to a requirement to preserve data for legal proceedings, which is different from tracking evidence handling​.

Thus, the correct answer isD, as chain of custody directly relates to tracking who had access to the evidence and when​.

The correct answer is B because a legal hold requires the organization to preserve potentially relevant information. The first practical step is to notify the departments, custodians, IT staff, and records personnel who may control or possess relevant emails so they do not delete, alter, or overwrite them.

Exact supporting extract: the Secbay CySA+ guide defines legal hold as a process used to preserve relevant information associated with legal proceedings, investigations, or disputes. It states that once a legal hold is in effect, it is crucial to communicate it to relevant personnel who may have custody or control over the information, including IT staff, records management personnel, and employees with pertinent data.

The Sybex CySA+ Study Guide also states that legal holds require organizations to preserve all potentially relevant data and information related to pending or active litigation. It specifically notes that legal holds may involve data such as logs, email, or transactional information that would otherwise be destroyed under normal retention procedures.

Why the other options are incorrect:

A is incorrect because disclosing the request to unrelated vendors could create confidentiality and legal issues.

C is incorrect because chain of custody is important when evidence is collected and transferred, but the first legal-hold step is preservation notification.

D is incorrect because producing mailbox copies to the attorney is premature. The organization must first preserve the relevant data and follow legal/eDiscovery procedures.

Defense evasion is the technique of avoiding detection or prevention by security tools or mechanisms. In this case, the freeware program is likely a malware that generates random DNS queries to communicate with a command and control server or exfiltrate data. The command Add-MpPreference -ExclusionPath ' %Program Filest\ksysconfig ' is used to add an exclusion path to Windows Defender, which is a built-in antivirus software, to prevent it from scanning the malware folder. References: CompTIA CySA+ Study Guide: Exam CS0-003, 3rd Edition, Chapter 5, page 204; CompTIA CySA+ CS0-003 Certification Study Guide, Chapter 5, page 212. pr

A vulnerability scan is a process of identifying and assessing the security weaknesses of a system or network. A vulnerability scan can help a security analyst to effectively identify the most security risks associated with a locally hosted server, such as missing patches, misconfigurations, outdated software, or exposed services. A vulnerability scan can also provide recommendations on how to remediate the identified vulnerabilities and improve the security posture of the server12 References: 1: What is a Vulnerability Scan? | Definition and Examples 2: Securing a server: risks, challenges and best practices - Vaadata

A social engineering attack is a type of cyberattack that relies on manipulating human psychology rather than exploiting technical vulnerabilities. A social engineering attack may involve deceiving, persuading, or coercing users into performing actions that benefit the attacker, such as clicking on malicious links, divulging sensitive information, or granting access to restricted resources. An obfuscated link is a link that has been disguised or altered to hide its true destination or purpose. Obfuscated links are often used by attackers to trick users into visiting malicious websites or downloading malware. In this case, an incident response analyst notices multiple emails traversing the network that target only the administrators of the company. The email contains a concealed URL that leads to an unknown website in another country. This indicates that the analyst is witnessing a social engineering attack using obfuscated links.

The firewall certificate expired. If the firewall uses a certificate to authenticate and encrypt the feed, and the certificate expires, the feed will stop working until the certificate is renewed or replaced. Thiscan affect the data enrichment process and the security analysis. References: CompTIA CySA+ Study Guide: Exam CS0-003, 3rd Edition, Chapter 4: Security Operations and Monitoring, page 161.

The next action that the CSIRT should conduct after isolating the compromised server from the network is to take a snapshot of the compromised server and verify its integrity. Taking a snapshot of the compromised server involves creating an exact copy or image of the server’s data and state at a specific point in time. Verifying its integrity involves ensuring that the snapshot has not been altered, corrupted, or tampered with during or after its creation. Taking a snapshot and verifying its integrity can help preserve and protect any evidence or information related to the incident, as well as prevent any tampering, contamination, or destruction of evidence.

Single Sign-On (SSO) allows users to log in with a single ID and password to access multiple applications. It eliminates the need for different passwords for various internal applications, streamlining the authentication process.

The code snippet provided suggests an SQL injection vulnerability, indicated by the use of " 1=1, " which is a common SQL injection technique to bypass authentication. To mitigate this risk, validating user input is the most effective control, as it ensures that any input is properly sanitized and escapes potentially malicious characters before interacting with the database. This is a key principle from CompTIA Security+ guidelines on secure coding practices. Options A and B are unrelated to the vulnerability type here, and while access control (Option C) is generally good practice, it does not specifically prevent SQL injection.

The hard disk is the piece of data that should be collected first in order to preserve sensitive information before isolating the server. The hard disk contains all the files and data stored on the server, which may include evidence of malicious activity, such as malware installation, data exfiltration, or configuration changes. The hard disk should be collected using proper forensic techniques, such as creating an image or a copy of the disk and maintaining its integrity using hashing algorithms.

The correct answer is A. Implanted a backdoor.

A backdoor is a method that allows an unauthorized user to access a system or network without the permission or knowledge of the owner. A backdoor can be installed by exploiting a software vulnerability, by using malware, or by physically modifying the hardware or firmware of the device. A backdoor can be used for various malicious purposes, such as stealing data, installing malware, executing commands, or taking control of the system.

In this case, the consultant implanted a backdoor in the website by using an HTML and PHP code snippet that displays an image of a shutdown button and an alert message that says “Exit”. However, the code also echoes the remote address of the server, which means that it sends the IP address of the visitor to the attacker. This way, the attacker can identify and target the visitors of the website and use their IP addresses to launch further attacks or gain access to their devices.

The code snippet is an example of a clickjacking attack, which is a type of interface-based attack that tricks a user into clicking on a hidden or disguised element on a webpage. However, clickjacking is not the main goal of the consultant, but rather a means to implant the backdoor. Therefore, option C is incorrect.

Option B is also incorrect because privilege escalation is an attack technique that allows an attacker to gain higher or more permissions than they are supposed to have on a system or network. Privilege escalation can be achieved by exploiting a software vulnerability, by using malware, or by abusing misconfigurations or weak access controls. However, there is no evidence that the consultant implemented privilege escalation on the website or gained any elevated privileges.

Option D is also incorrect because patching is a process of applying updates to software to fix errors, improve performance, or enhance security. Patching can prevent or mitigate various types of attacks, such as exploits, malware infections, or denial-of-service attacks. However, there is no indication that the consultant patched the web server or improved its security in any way.

SLA stands for Service Level Agreement, which is a contract that defines the various levels of maintenance to be provided by an external business vendor in a secure environment. An SLA specifies the expectations, responsibilities, and obligations of both parties, such as the scope, quality, availability, and performance of the service, as well as the metrics and methods for measuring and reporting the service level. An SLA also outlines the penalties or remedies for any breach or failure of the service level. An SLA can help ensure that the external business vendor delivers the service in a timely, consistent, and secure manner, and that the customer receives the service that meets their needs and requirements. Official References:

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

https://www.comptia.org/certifications/cybersecurity-analyst

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

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.

One of the best actions to take after the conclusion of a security incident to improve incident response in the future is to schedule a review with all teams to discuss what occurred, what went well, what went wrong, and what can be improved. This review is also known as a lessons learned session or an after-action report. The purpose of this review is to identify the root causes of the incident, evaluate the effectiveness of the incident response process, document any gaps or weaknesses in the security controls, and recommend corrective actions or preventive measures for future incidents. Official References: https://www.eccouncil.org/cybersecurity-exchange/threat-intelligence/cyber-kill-chain-seven-steps-cyberattack/

Agent-based scansare runlocally on hostsvia installed agents, whichsignificantly reduces network trafficwhile allowing in-depth visibility and accurate scanning. They’re ideal for bandwidth-limited or sensitive networks.

Credentialed scans (A)still transmit data over the network.

Individual scans (B)is ambiguous and not a standard term.

Baseline scans (C)focus on policy compliance, not reducing traffic.

?Reference:

Chapple & Seidl – Vulnerability Management, Chapter 6: Scanning Techniques

CS0-003 Domain 2.1 – Vulnerability Scanning Methods

The vulnerability is network based is the correct attribute that describes this vulnerability, as it can be inferred from the CVSS string. CVSS stands for Common Vulnerability Scoring System, which is a framework that assigns numerical scores and ratings to vulnerabilities based on their characteristics and severity. The CVSS string consists of several metrics that define different aspects of the vulnerability, such as the attack vector, the attack complexity, the privileges required, the user interaction, the scope, and the impact on confidentiality, integrity and availability. The first metric in the CVSS string is the attack vector (AV), which indicates how the vulnerability can be exploited. The value of AV in this case is N, which stands for network. This means that the vulnerability can be exploited remotely over a network connection, without physical or logical access to the target system. Therefore, the vulnerability is network based. Official References:

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

https://www.comptia.org/certifications/cybersecurity-analyst

https://packitforwarding.com/index.php/2019/01/10/comptia-cysa-common-vulnerability-scoring-system-cvss/

Application security scanning is a process that involves testing and analyzing applications for security vulnerabilities, such as injection flaws, broken authentication, cross-site scripting, and insecure configuration. Application security scanning can help identify and fix security issues before they become exploitable by attackers. Using application security scanning as part of the pipeline for the continuous integration/continuous delivery (CI/CD) flow can help mitigate the problem of finding the same vulnerabilities in a critical application during security scanning. This is because application security scanning can be integrated into the development lifecycle and performed automatically and frequently as part of the CI/CD process.