CAS-005 Exam Dumps : CompTIA SecurityX Certification Exam

The presence of an unauthorized server (29mail.mycrosoft.info) sending emails on behalf of the company indicates a potential spoofing or phishing attempt. To mitigate this:

Remove the unnecessary servers from the SPF record (Option C): The Sender Policy Framework (SPF) specifies which mail servers are authorized to send emails on behalf of a domain. Removing unauthorized or unnecessary servers from the SPF record helps prevent spoofed emails from passing SPF checks.

Change the SPF record to enforce the hard fail parameter (Option D): Setting the SPF policy to a hard fail (-all) ensures that emails from unauthorized servers are rejected, enhancing email security.

Implementing these changes strengthens the domain's email authentication mechanisms, reducing the risk of successful phishing or spoofing attacks.

The event timeline indicates a sequence where a file (hr-reporting.docx) was saved, scanned, executed, and eventually found to contain malware. The critical issue here is that the malware scan completed after the file was already executed. This suggests a Time-Of-Check to Time-Of-Use (TOCTOU) vulnerability, where the state of the file changed between the time it was checked and the time it was used.

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 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 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.