CompTIA Updated CAS-005 Exam Questions and Answers by mylo

When a security analyst receives a notification about an attack that appears to originate from an internal vulnerability scanner, it suggests that the scanner itself might have been compromised. This situation is critical because a compromised scanner can potentially conduct unauthorized scans, leak sensitive information, or execute malicious actions within the network. Theappropriate first action involves containing the threat to prevent further damage and allow for a thorough investigation.

Here’s why quarantining the scanner sensor is the best immediate action:

Containment and Isolation: Quarantining the scanner will immediately prevent it from continuing any malicious activity or scans. This containment is crucial to protect the rest of the network from potential harm.

Forensic Analysis: By isolating the scanner, a forensic analysis can be performed to understand how it was compromised, what actions it took, and what data or systems might have been affected. This analysis will provide valuable insights into the nature of the attack and help in taking appropriate remedial actions.

Preventing Further Attacks: If the scanner is allowed to continue operating, it might execute more unauthorized actions, leading to greater damage. Quarantine ensures that the threat is neutralized promptly.

Root Cause Identification: A forensic analysis can help identify vulnerabilities in the scanner’s configuration, software, or underlying system that allowed the compromise. This information is essential for preventing future incidents.

Other options, while potentially useful in the long term, are not appropriate as immediate actions in this scenario:

A. Create an allow list for the vulnerability scanner IPs to avoid false positives: This action addresses false positives but does not mitigate the immediate threat posed by the compromised scanner.

B. Configure the scan policy to avoid targeting an out-of-scope host: This step is preventive for future scans but does not deal with the current incident where the scanner is already compromised.

C. Set network behavior analysis rules: While useful for ongoing monitoring and detection, this does not address the immediate need to stop the compromised scanner’s activities.

In conclusion, the first and most crucial action is to quarantine the scanner sensor to halt any malicious activity and perform a forensic analysis to understand the scope and nature of the compromise. This step ensures that the threat is contained and provides a basis for further remediation efforts.

Tokenizationreplaces sensitive data (e.g., PII) with non-sensitive placeholders while maintaining format consistency, ensuring compliancewithout disrupting testing. This method is commonly used forPCI-DSS and GDPR compliancewhile preserving data structure for functional tests.

Encryption (A)secures data but does not remove sensitivity or solve testing concerns.

Truncation (B)removes portions of data but may impact testing if format requirements are strict.

Synthetic data (C)can be useful but may not always match real-world scenarios perfectly for testing purposes.

To improve the vulnerability management process in an environment where new devices/IPs are added and dropped regularly, the company should perform regular discovery scanning throughout the IT landscape using the vulnerability management tool. Here’s why:

Accurate Asset Inventory: Regular discovery scans help maintain an up-to-date inventory of all assets, ensuring that the vulnerability management process includes all relevant devices and IPs.

Consistency in Reporting: By continuously discovering and scanning new and existing assets, the company can generate consistent and comprehensive vulnerability reports that reflect the current state of the network.

Proactive Management: Regular scans enable the organization to proactively identify and address vulnerabilities on new and existing assets, reducing the window of exposure to potential threats.

Sinkholing, or DNS sinkholing, is a method used to redirect malicious traffic to a safe destination. This technique is often employed by security teams to prevent access to malicious domains by substituting a benign destination IP address.

In the given logs, users from the finance department are accessing www.bank.com and receiving HTTP status code 495. This status code is typically indicative of a client certificate error, which can occur if the DNS traffic is being manipulated or redirected incorrectly. The consistency in receiving the same HTTP status code across different users suggests a systematic issue rather than an isolated incident.

Recursive DNS resolution failure (A) would generally lead to inability to resolve DNS at all, not to a specific HTTP error.

DNS poisoning (B) could result in usersbeing directed to malicious sites, but again, would likely result in a different set of errors or unusual activity.

Incorrect DNS setup (D) would likely cause broader resolution issues rather than targeted errors like the one seen here.

By reviewing the provided data, it is evident that the DNS traffic for www.bank.com is being rerouted improperly, resulting in consistent HTTP 495 errors for the finance department users. Hence, the most likely cause is that the DNS traffic is being sinkholed.