CompTIA Updated CS0-003 Exam Questions and Answers by sean

Segmenting the entire department from the network and reviewing each computer offline is the first step the incident response staff members should take when they arrive. This step can help contain the malware infection and prevent it from spreading to other systems or networks. Reviewing each computer offline can help identify the source and scope of the infection, and determine the best course of action for recovery12. Turning on all systems, scanning for infection, and backing up data to a USB storage device is a risky step, as it can activate the malware and cause further damage or data loss. It can also compromise the USB storage device and any other system that connects to it. Identifying and removing the software installed on the impacted systems in the department is a possible step, but it should be done after segmenting the department from the network and reviewing each computer offline. Explaining that malware cannot truly be removed and then reimaging the devices is a drastic step, as it can result in data loss and downtime. It should be done only as a last resort, and after backing up the data and verifying its integrity. Logging on to the impacted systems with an administrator account that has privileges to perform backups is a dangerous step, as it can expose the administrator credentials and privileges to the malware, and allow it to escalate its access and capabilities34. References: Incident Response: Processes, Best Practices & Tools - Atlassian, Incident Response Best Practices | SANS Institute, Malware Removal: How to Remove Malware from Your Device, How to Remove Malware From Your PC | PCMag

Fuzzing is a process used to test applications by inputting unexpected or random data to see how the application behaves. This method is particularly effective in identifying vulnerabilities such as buffer overflows, input validation errors, and other anomalies that could cause the application to crash or behave unexpectedly. By using fuzzing, the security team can ensure the new application is robust and capable of handling unexpected strings with anomalous formats without crashing.

The given firewall logs indicatehigh outbound traffic with low IP reputation, sustained over time, which is a strongindicator of cryptomining activity​.

Option A (Anomalous activity)is a general term but does not specifywhythe activity is suspicious.

Option B (Bandwidth saturation)occurs when network traffic is overwhelming, but cryptomining typicallyuses CPU/GPU powerrather than overwhelming bandwidth.

Option D (Denial of service - DoS)would result incontinuous large requests, but cryptomining generatesconsistent, high-bandwidth outbound trafficrather than bursts of large requests.

Thus,C is the correct answer, as cryptomininggenerates unusual outbound network activity from internal hosts to mining pools​.

Comprehensive and Detailed Explanation From Exact Extract:

Incident response playbooks are preplanned, step-by-step procedures used to respond consistently and effectively to specific incident types. Their importance is that they provide tactical guidance during stressful situations, particularly in the early hours, to ensure a measured, repeatable response that reduces impact and supports recovery.

The Sybex CySA+ Study Guide directly defines what playbooks are and why they matter:

Exact extract (Sybex Study Guide):

“CSIRT teams often develop playbooks that describe the specific procedures that they will follow in the event of a specific type of cybersecurity incident.”

It also explains the practical purpose: responders can use them as an operational plan, especially early in response:

Exact extract (Sybex Study Guide):

“The idea behind the playbook is that the team should be able to pick it up and find an operational plan for responding to the security incident that they may follow. Playbooks are especially important in the early hours of incident response…”

The Secbay Press CS0-003 guide reinforces that playbooks are step-by-step instructions and that they streamline response and ensure consistency:

Exact extract (Secbay Press):

“Creation of incident response playbooks detailing step-by-step instructions for responding to common types of security incidents. Playbooks streamline response efforts and ensure consistency across incidents.”

Therefore, Option D is the best answer because it matches the step-by-step, preplanned nature of playbooks and their goal of minimizing impact and supporting restoration/recovery.

Why the other options are not best:

A: Compliance alignment is not the primary function of IR playbooks; playbooks are operational response guides.

B: Preventing incidents is more about security controls/hardening; playbooks are for responding when incidents occur.

C: Metrics/KPIs and lessons learned are part of post-incident improvement, but playbooks aren’t primarily “baseline requirements for monitoring.” They’re response procedures.

References (CompTIA CySA+ CS0-003 documents / study guides used):

Mike Chapple & David Seidl, CompTIA CySA+ Study Guide (CS0-003): playbooks describe specific procedures; operational plan; importance early in incident response

Secbay Press, CompTIA CySA+ Exam Prep Guide (CS0-003): playbooks are step-by-step instructions; streamline response; ensure consistency