CompTIA CS0-003 - CompTIA CyberSecurity Analyst CySA+ Certification Exam

A tabletop exercise is a type of simulation exercise that involves testing possible incident scenarios and how to react properly, without actually performing any actions or using any resources. A tabletop exercise is usually conducted by a facilitator who presents a realistic scenario to a group of participants, such as a cyberattack, a natural disaster, or a data breach. The participants then discuss and evaluatetheir roles, responsibilities, plans, procedures, and policies for responding to the incident, as well as the potential impacts and outcomes. A tabletop exercise can help identify strengths and weaknesses in the incident response plan, improve communication and coordination among the stakeholders, raise awareness and preparedness for potential incidents, and provide feedback and recommendations for improvement.

This VM has a public IP and an open port 80, which violates the company’s security requirements of no public IPs and no insecure ports/protocols. It also exposes the VM to potential attacks from the internet. This VM should be updated first to use a private IP and close the port 80, or use a secure protocol such as HTTPS.

References[CompTIA CySA+ Study Guide: Exam CS0-003, 3rd Edition], Chapter 2: Cloud and Hybrid Environments, page 67.[What is a Public IP Address?][What is Port 80?]

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.

Webhooksenable automatic and event-driven interactions between applications. In the context of code repositories and vulnerability scanning, webhooksautomate the scanning processevery time new code is committed. Thisensures continuous security coveragewithout relying on manual triggers, thereby embedding security checks into the development lifecycle efficiently. This automation leads to improved coverage and faster identification of vulnerabilities at the earliest stage possible in the DevSecOps pipeline.

TheDiamond Model of Intrusion Analysisconsists offour core attributes:

Adversary– The threat actor behind the attack.

Capability– The tools and techniques used.

Infrastructure– The systems used by the adversary (e.g., botnets, C2 servers).

Victim– The target of the attack​.

Option A (Delivery)andOption B (Weaponization)are part of theCyber Kill Chain, not the Diamond Model.

Option C (Command and control)is an attack phase butnot a core attribute of the Diamond Model.

Option D (Capability) is correct, as it represents the tools and attack methods used by adversaries.

Thus,D is the correct answer.

Thelessons learnedphase is a formal step in the incident response process where teamsreview what went wrong, what worked, and how to improvefuture responses. Management uses this toadjust policies, procedures, and controlsbased on real incident experiences.

Tabletop (A)is a simulated discussion, not post-incident.

Root cause analysis (C)finds technical origins but doesn’t focus on process improvement.

Forensics (D)supports investigation but not process revision.

📘Reference:

CS0-003 Domain 3.0 – Post-Incident Activities

Chapple & Seidl – Study Guide, Chapter 11: Containment and Recovery

Timeline analysis in digital forensics involves creating a chronological sequence of events based on system logs, file changes, and other forensic data. This process often uses graphical representations to illustrate and analyze how an incident unfolded over time, making it easier to identify key events and potential indicators of compromise. This approach is highlighted in CompTIA Cybersecurity Analyst (CySA+) practices as crucial for understanding the scope and sequence of a security incident. The other options do not involve chronological or graphical analysis to the extent that timeline analysis does.

This is a type of web application vulnerability called cross-site scripting (XSS), which allows an attacker to inject malicious code into a web page that is viewed by other users. XSS can be used to steal cookies, session tokens, credentials, or other sensitive information, or to perform actions on behalf of the victim.

Input sanitization is a technique that prevents XSS attacks by checking and filtering the user input before processing it. Input sanitization can remove or encode any characters or strings that may be interpreted as code by the browser, such as <, >, ", ', or javascript:. Input sanitization can also validate the input against a predefined format or range of values, and reject any input that does not match.

Output encoding is a technique that prevents XSS attacks by encoding the output before sending it to the browser. Output encoding can convert any characters or strings that may be interpreted as code by the browser into harmless entities, such as <, >, ", ', or javascript:. Output encoding can also escape any special characters that may have a different meaning in different contexts, such as , /, or ;.

Code obfuscation is a technique that makes the source code of a web application more difficult to read and understand by humans. Code obfuscation can use techniques such as renaming variables and functions, removing comments and whitespace, replacing literals with expressions, or adding dummy code. Code obfuscation can help protect the intellectual property and trade secrets of a web application, but it does not prevent XSS attacks.

To mitigate brute-force attacks, implementing an account lockout policy (C) prevents continuous attempts by locking the account after a set number of failed logins. Blocking inbound connections on TCP port 3389 (RDP) from untrusted IP addresses (F) limits access, reducing the attack surface. According to CompTIA Security+, these controls effectively prevent unauthorized access. While blocking specific IPs (D) or disabling RDP (E) can also help, the lockout and firewall rules provide broader, proactive protection against this attack type.

An incident response plan is a set of predefined procedures and guidelines that an organization follows when faced with a security breach or attack. An incident response plan helps to ensure that the organization can quickly and effectively contain, analyze, eradicate, and recover from the incident, as well as prevent or minimize the damage and impact to the business operations, reputation, andcustomers. An incident response plan also defines the roles and responsibilities of the incident response team, the communication channels and protocols, the escalation and reporting procedures, and the tools and resources available for the incident response.

By following the company’s incident response plan, the administrator can ensure that they are following the best practices and standards for handling a security incident, and that they are coordinating and collaborating with the relevant stakeholders and authorities. Following the company’s incident response plan can also help to avoid or reduce any legal, regulatory, or contractual liabilities or penalties that may arise from the incident.

The other options are not as effective or appropriate as following the company’s incident response plan. Informing the internal incident response team (A) is a good step, but it should be done according to the company’s incident response plan, which may specify who, when, how, and what to report. Reviewing the lessons learned for the best approach © is a good step, but it should be done after the incident has been resolved and closed, not during the active response phase. Determining when the access started (D) is a good step, but it should be done as part of the analysis phase of the incident response plan, not before following the plan.