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

The output shows the results of a port scan, which is a technique used to identify open ports and services running on a network host. Port scanning can be used by attackers to discover potential vulnerabilities and exploit them, or by defenders to assess the security posture and configuration of their network devices1

The output lists six ports that are open on the target host, along with the service name and version associated with each port. The service name indicates the type of application or protocol that is using the port, while the version indicates the specific release or update of the service. The service name and version can provide useful information for both attackers and defenders, as they can reveal the capabilities, features, and weaknesses of the service.

Among the six ports listed, two are particularly risky and should be investigated further by the security team: port 23 and port 636.

Port 23 is used by Telnet, which is an old and insecure protocol for remote login and command execution. Telnet does not encrypt any data transmitted over the network, including usernames and passwords, which makes it vulnerable to eavesdropping, interception, and modification by attackers. Telnet also has many known vulnerabilities that can allow attackers to gain unauthorized access, execute arbitrary commands, or cause denial-of-service attacks on the target host23

Port 636 is used by LDAP over SSL/TLS (LDAPS), which is a protocol for accessing and modifying directory services over a secure connection. LDAPS encrypts the data exchanged between the client and the server using SSL/TLS certificates, which provide authentication, confidentiality, and integrity. However, LDAPS can also be vulnerable to attacks if the certificates are not properly configured, verified, or updated. For example, attackers can use self-signed or expired certificates to perform man-in-the-middle attacks, spoofing attacks, or certificate revocation attacks on LDAPS connections.

Therefore, the security team should investigate further why port 23 and port 636 are open on the target host, and what services are running on them. The security team should also consider disabling or replacing these services with more secure alternatives, such as SSH for port 23 and StartTLS for port 6362

A rollback had been executed on the instance. If a database server is restored to a previous state, it may reintroduce a vulnerability that was previously fixed. This can happen due to backup and recovery operations, configuration changes, or software updates. A rollback can undo the patching or mitigation actions that were applied to remediate the vulnerability. References: Vulnerability Remediation: It’s Not Just Patching, Section: The Remediation Process; Vulnerability assessment for SQL Server, Section: Remediation

1. Analyze the Screenshot: The provided image shows a vulnerability scan report (likely from OWASP ZAP). The specific alert highlighted in blue is " Cross-Domain Misconfiguration " with 34 occurrences. In CompTIA performance-based questions, the highlighted item dictates the problem you need to solve.

2. Identify the Vulnerability: Cross-Domain Misconfiguration typically refers to issues with CORS (Cross-Origin Resource Sharing).

CORS is a mechanism that allows a server to indicate any other origins (domains, schemes, or ports) than its own from which a browser should permit loading of resources.

A common misconfiguration occurs when the server sends the header Access-Control-Allow-Origin: *. This wildcard tells the browser to allow any website to access the resources on your server, which defeats the browser ' s Same-Origin Policy protection.

3. Evaluate the Solution (Option C): To tune this and fix the vulnerability without breaking functionality for legitimate partners, the analyst should change the configuration from a wildcard (*) to a specific allowlist.

Remediation: Set the Access-Control-Allow-Origin header to strictly define which authorized domains (e.g., https://partner.example.com) are allowed to access the resources.

This aligns perfectly with Option C.

Why the other options are incorrect:

A. Set an HttpOnly flag to force communication by HTTPS:

This is incorrect for two reasons. First, it addresses the " Cookie No HttpOnly Flag " alert, not the highlighted " Cross-Domain " alert. Second, the definition is technically wrong: the HttpOnly flag prevents client-side scripts (like JavaScript) from accessing cookies (mitigating XSS); it does not force HTTPS. The Secure flag or HSTS headers are used to force HTTPS.

B. Block requests without an X-Frame-Options header:

This is the remediation for Clickjacking (seen in the alert list as " Missing Anti-clickjacking Header " ), not Cross-Domain Misconfiguration.

D. Disable the cross-origin resource sharing header:

While removing the header entirely defaults the browser back to the strict Same-Origin Policy (which is secure), " tuning " implies adjusting the setting to work correctly. If the application requires cross-domain communication (which the presence of the header suggests), disabling it entirely would break the application. Configuring it correctly (Option C) is the professional remediation.