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

AUSB drop attackis acommon method for delivering ransomware, where an attacker leaves infected USB drives in strategic locations,tricking employees into plugging them into corporate devices​.

Option B (LFI - Local File Inclusion)exploitsweb applications, but the scenario lacksnetwork intrusion indicators.

Option C (Cross-site request forgery - CSRF)is used forexploiting authenticated web sessions, not ransomware delivery.

Option D (SQL injection)is used fordatabase exploitation, not file encryption malware.

Thus,A (USB drop) is the correct answer, asphysical malware introduction is a known ransomware attack vector​.

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.

A HTTP/404 error code means that the requested page or resource was not found on the web server. This could be caused by various reasons, such as incorrect URLs, moved or deleted pages, missing assets, or server misconfigurations123. The analyst should first identify the source of the requests and examine the related activity to determine if they are legitimate or malicious, and what actions need to be taken to resolve the issue. The other options are either premature or irrelevant without further investigation. References: 1: 404 Page Not Found Error: What It Is and How to Fix It 2: 404 Error Code: What Causes Them and How To Fix It 3: About 404 errors and how to Troubleshoot it?

A tabletop exercise is the most likely action that an analyst would perform after an incident has been investigated. A tabletop exercise is a simulation of a potential incident scenario that involves the key stakeholders and decision-makers of the organization. The purpose of a tabletop exercise is to evaluate the effectiveness of the incident response plan, identify the gaps and weaknesses in the plan, and improve the communication and coordination among the incident response team and other parties. A tabletop exercise can help the analyst to learn from the incident investigation, test the assumptions and recommendations made during the investigation, and enhance the preparedness and resilience of the organization for future incidents12. Risk assessment, root cause analysis, and incident response plan are all actions that an analyst would perform before or during an incident investigation, not after. Risk assessment is the process of identifying, analyzing, and evaluating the risks that may affect the organization. Root cause analysis is the method of finding the underlying or fundamental causes of an incident. Incident response plan is the document that defines the roles, responsibilities, procedures, and resources for responding to an incident345. References: Tabletop Exercises: Six Scenarios to Help Prepare Your Cybersecurity Team, Tabletop Exercises for Incident Response - SANS Institute, Risk Assessment - NIST, Root Cause Analysis - OWASP, Incident Response Plan | Ready.gov

Transfer is the risk management principle that is accomplished by purchasing cyber insurance. Transfer is a strategy that involves shifting the risk or its consequences to another party, such as an insurance company, a vendor, or a partner. Transfer does not eliminate the risk, but it reduces the potential impact or liability of the risk for the original party. Cyber insurance is a type of insurance that covers the losses and damages resulting from cyberattacks, such as data breaches, ransomware, denial-of-service attacks, or network disruptions. Cyber insurance can help transfer the risk of cyber incidents by providing financial compensation, legal assistance, or recovery services to the insured party. 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

The best security control to implement against sensitive information being disclosed via file sharing services is to improve employee training and awareness. Employee training and awareness can help educate employees on the risks and consequences of using file sharing services for sensitive information, as well as the policies and procedures for handling such information securely and appropriately. Employee training and awareness can also help foster a security culture and encourage employees to report any incidents or violations of information security.

After detecting a compromised email server and unusual network traffic, the next step in incident response is containment, to prevent further damage or spread of the compromise. References: CompTIA CySA+ Study Guide: Exam CS0-003, 3rd Edition, Chapter 5: Incident Response, page 197.

MITRE ATT&CK is a framework and knowledge base that describes the tactics, techniques, and procedures (TTPs) used by various adversaries in cyberattacks. MITRE ATT&CK can help security analysts compare TTPs between different known adversaries of an organization, as well as identify patterns, gaps, or trends in adversary behavior. MITRE ATT&CK can also help security analysts improve threat detection, analysis, and response capabilities, as well as share threat intelligence with other organizations or communities

Business process interruption is the inhibitor to remediation that this scenario illustrates. Business process interruption is when the remediation of a vulnerability or an incident requires the disruption or suspension of a critical or essential business process, such as the point-of-sale application. This can cause operational, financial, or reputational losses for the organization, and may outweigh the benefits of the remediation. Therefore, the organization may decide to postpone or avoid the remediation until a more convenient time, such as a change freeze window, which is a period of time when no changes are allowed to the IT environment12. Service-level agreement, degrading functionality, and proprietary system are other possible inhibitors to remediation, but they are not relevant to this scenario. Service-level agreement is when the remediation of a vulnerability or an incident violates or affects the contractual obligations or expectations of the service provider or the customer. Degrading functionality is when the remediation of a vulnerability or an incident reduces or impairs the performance or usability of a system or an application. Proprietary system is when the remediation of a vulnerability or an incident involves a system or an application that is owned or controlled by a third party, and the organization has limited or no access or authority to modify it3. References: Inhibitors to Remediation — SOC Ops Simplified, Remediation Inhibitors - CompTIA CySA+, Information security Vulnerability Management Report (Remediation…

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