CompTIA Updated CAS-005 Exam Questions and Answers by madeleine

The best solution is to implement authentication for API requests and apply appropriate rate limiting (C). Authentication ensures that only authorized customers or systems can access the API, while rate limiting helps prevent denial-of-service (DoS)-like conditions and cost inflation from excessive or malicious requests. This addresses both the security (unauthorized access) and cost issues (serverless billing based on execution).

Option A (digital certificates) is a strong control for authentication but may introduce unnecessary complexity and does not address rate abuse directly. Option B (rate limits with IP reputation checks) is useful but insufficient—malicious actors may rotate through new IPs not yet flagged. Option D (regional restrictions) might reduce some noise traffic but risks blocking legitimate global users and is not scalable for a modern cloud service.

CAS-005 highlights securing APIs with authentication, authorization, and throttling as best practices. Thus, the combined approach of API authentication plus rate limiting is the most comprehensive and effective solution.

The correct answer is Playbooks (A). In incident response, playbooks are structured workflows that define step-by-step actions for specific incident types (e.g., ransomware, phishing, insider threats). They allow SOC analysts to standardize responses across multiple platforms and tools, ensuring consistency and faster mitigation. By leveraging playbooks, organizations integrate existing incident response tools into automated or semi-automated processes, improving efficiency and reducing human error.

Option B (event collectors) consolidate logs but do not directly improve response processes. Option C (centralized logging) enhances visibility but does not provide a framework for action. Option D (endpoint detection) expands detection capabilities but does not enhance the process effectiveness of incident response.

CAS-005 emphasizes structured response through automation and orchestration. Playbooks, often implemented via SOAR platforms, allow integration of detection, triage, and remediation steps, making them the most effective way to increase incident response maturity.

To prevent unauthorized applications from running, the company needs a mechanism to explicitly define and enforce which applications are allowed to execute. "Permit listing" (often referred to as "whitelisting" in security contexts) is the most effective solution here. It involves creating a list of approved applications, and only those on the list are permitted to run, blocking all others by default. This directly addresses the root cause—users installing unapproved software—by restricting execution to only authorized programs.

Option A (Signing):Code signing ensures the authenticity and integrity of software by verifying it comes from a trusted source and hasn’t been tampered with. While useful, it doesn’t inherently prevent unauthorized applications from running unless combined with a policy like whitelisting.

Option B (Access control):Access control governs who can access systems or resources but doesn’t specifically restrict which applications can execute. It’s too broad for this scenario.

Option C (HIPS):A Host-based Intrusion Prevention System (HIPS) can detect and block malicious behavior, but it’s reactive and relies on signatures or heuristics, not a proactive allow-only approach.

Option D (Permit listing):This is the best fit, as it proactively enforces a policy where only explicitly authorized applications can run, preventing malware introduced by unauthorized software.

The most appropriate solution for the systems engineer to deploy is SELinux (Security-Enhanced Linux). Here's why:

Mandatory Access Control (MAC): SELinux enforces MAC policies, ensuring that only authorized users and processes can access specific resources. This helps in preventing unauthorized reading and modification of data and programs.

Access Vector Cache: SELinux utilizes an access vector cache (AVC) to improve performance. The AVC caches access decisions, reducing the need for repetitive policy lookups and thus improving system efficiency.

Security Mechanisms: SELinux provides a robust framework to enforce security policies and prevent bypassing of application security mechanisms. It controls access based on defined policies, ensuring that security measures are consistently applied.

Privilege Escalation and Process Interference: SELinux limits the ability of processes to escalate privileges and interfere with each other by enforcing strict access controls. This containment helps in isolating processes and minimizing the risk of privilege escalation attacks.