Free Practice Questions for CompTIA CS0-003 Exam

The correct answer is B. Allowlisting.

Allowlisting is a technique that allows only pre-approved web-based software to run on a system or network, while blocking all other software. Allowlisting can help prevent unauthorized or malicious software from compromising the security of an organization. Allowlisting can be implemented using various methods, such as application control, browser extensions, firewall rules, or proxy servers12.

The other options are not the best techniques to ensure that users only leverage web-based software that has been pre-approved by the organization. Blocklisting (A) is a technique that blocks specific web-based software from running on a system or network, while allowing all other software. Blocklisting can be ineffective or inefficient, as it requires constant updates and may not catch all malicious software. Graylisting © is a technique that temporarily rejects or delays incoming messages from unknown or suspicious sources, until they are verified as legitimate. Graylisting is mainly used for email filtering, not for web-based software control. Webhooks (D) are a technique that allows web-based software to send or receive data from other web-based software in real time, based on certain events or triggers. Webhooks are not related to web-based software control, but rather to web-based software integration.

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.

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.

Weaponization is the stage of the Cyber Kill Chain where the threat actor creates or modifies a malicious tool to use against a target. In this case, the threat actor compiles and tests a malicious downloader, which is a type of weaponized malware. References: Cybersecurity 101, The Cyber Kill Chain: The Seven Steps of a Cyberattack

An incident manager should work with the legal and public relations entities to ensure correct processes are adhered to when communicating incident reporting to the general public, as a best practice. The legal entity can provide guidance on the legal implications and obligations of disclosing the incident, such as compliance with data protection laws, contractual obligations, and liability issues. The public relations entity can help craft the appropriate message and tone for the public communication, as well as manage the reputation and image of the organization in the aftermath of the incident. These two entities can help the incident manager balance the need for transparency and accountability with the need for confidentiality and security12. References: Incident Communication Templates, Incident Management: Processes, Best Practices & Tools - Atlassian

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

Mean Time to Detect (MTTD) is the most appropriate Key Performance Indicator (KPI) to monitor the effectiveness of an incident response reporting and communication program among the choices provided.

Why B is correct: The primary goal of an " incident reporting " program (whether automated by tools or reported by users/staff) is to alert the security team to an issue as quickly as possible. MTTD measures the average time it takes for an organization to identify (detect and report) an incident after it has occurred. A lower MTTD directly indicates that the reporting mechanisms and communication channels from the source to the analysts are operating effectively.

Why A is incorrect: Incident volume measures the quantity of incidents, which reflects the threat landscape or workload rather than the effectiveness of the response program itself. While an increase in user-reported volume can indicate better awareness, MTTD is the standard performance metric for the process.

Why C is incorrect: Average time to patch is a KPI for Vulnerability Management, not Incident Response reporting.

Why D is incorrect: Remediated incidents refers to the volume of resolved issues (Response/Recovery phase) and does not specifically measure the speed or quality of the reporting and communication (detection) phase.

In Domain 4 (Reporting and Communication) and Domain 1 (Security Operations), CompTIA emphasizes the use of time-based metrics to evaluate process maturity.

MTTD (Mean Time to Detect): Measures " dwell time " and the efficiency of the Detection & Reporting phase.

MTTR (Mean Time to Respond): Measures the efficiency of the Response & Recovery phase.

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The string provided ispercent-encoded text, commonly used toobfuscate URLs. When decoded, it translates towww.ice-ptic.com. Such encoding is used tobypass email security filtersandspam detectors, making the malicious link appear as benign or unreadable to the automated scanners.

Option Ais incorrect: The string does not match JavaScript shellcode formats.

Option CandDare unlikely and unrelated to the actual behavior.

?Reference:

CySA+ All-in-One Exam Guide by Mya Heath– Chapter 4, Obfuscated Links

CompTIA Exam Objectives: 1.2 – Indicators of Malicious Activity

The first action that should be completed to remediate the findings is to perform proper sanitization on all fields. Sanitization is a process that involves validating, filtering, or encoding any user input or data before processing or storing it on a system or application. Sanitization can help prevent various types of attacks, such as cross-site scripting (XSS), SQL injection, or command injection, that exploit unsanitized input or data to execute malicious scripts, commands, or queries on a system or application. Performing proper sanitization on all fields can help address the most critical and common vulnerability found during the vulnerability assessment, which is XSS.

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.