YARA rules are pattern-matching rules used to identify malware based on specific strings, conditions, and binary patterns. They are most effective in memory or file scans where analysts search for known indicators or unique signatures via string matching.

Correct answer: C. string matching.

Comprehensive and Detailed Explanation:

Endpoint Detection and Response (EDR) tools provide behavioral analytics and continuous monitoring to detect malware such as backdoors, which is especially critical on endpoints like macOS devices. These tools are essential to detect post-compromise activities and contain threats before they spread.

Secure Email Gateway (e.g., Cisco ESA) plays a key role in blocking phishing emails—the initial vector in this attack. It uses filters and reputation analysis to prevent malicious links or attachments from reaching end users.

Incorrect Options:

C. DLP focuses on preventing data exfiltration, not phishing prevention or backdoor detection.

D. IPS is effective for known signature-based threats but less effective against phishing links and endpoint-level backdoors.

E. WAF protects web servers, not end-user devices from phishing or backdoor infections.

Therefore, the correct answers are: A and B.

The repeated failed SSH authentications followed by a successful root login form a strong sequence indicating compromised user access. After entry, the account runs apt purge apache2, which removes the Apache package and its configuration data, directly explaining why customers can no longer reach the service. That command is an unauthorized system modification. Privilege escalation is not demonstrated because the successful session is already associated with root; no transition from lower to higher privilege is shown. The evidence also does not establish malware propagation or the traffic volume expected in a DDoS attack. CBRFIR Incident Response Techniques objectives 3.1 and 3.2 require responders to interpret security and system logs and correlate host and network activity by incident type. Here, authentication records and package-management activity create a coherent attack chain: credential compromise followed by destructive administrative action. Cisco CBRFIR v1.2 exam topics

Data loss prevention is the control most directly aligned with the incident’s root cause: an authorized insider removed sensitive customer information. DLP policies can identify regulated or confidential content, inspect transfers, alert on abnormal movement, and block unauthorized exfiltration through supported channels. Cisco explains that DLP uses rules to find sensitive information and detect abnormal transfers, including intentional disclosure of customer data. This makes option D a targeted post-incident recommendation under CBRFIR objectives 3.4 and 3.5. A penetration test may reveal exploitable technical weaknesses, antivirus addresses malware, and universal password changes address credential compromise; none directly controls misuse of legitimate access to move protected data. DLP should still be combined with least privilege, access reviews, logging, and user-behavior monitoring, but among the listed choices it best reduces recurrence. See Cisco’s DLP overview .