The incident stems from a policy-level issue rather than a technical vulnerability. According to incident response best practices, the priority should be to review and update firewall rules and ensure that the network security policy aligns with the principle of least privilege and correct access segmentation.

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

From the Wireshark capture:
A (iraniansk.com): This domain is not a known legitimate resource and is hosting a suspicious file named "Fy.
exe," strongly indicative of a malware distribution domain.
D (Fy.exe): The Content-Disposition: attachment; filename= " Fy.exe " header explicitly signals a binary executable download, a key indicator in Emotet campaigns.
While Content-Type: application/octet-stream (E) is typical of binary data transfers, it is not unique to malware and cannot by itself serve as a strong IoC. The nginx server (B) and cookie/hash string (C) similarly do not uniquely indicate compromise.

When dealing with suspected malicious activity involving obfuscated PowerShell scripts-especially when launched from Microsoft Word documents-behavioral analysis is the most critical next step. This approach helps in determining if the process chain is part of a known attack pattern, such as a phishing attempt using malicious macros that launch PowerShell for data exfiltration or payload download.
As highlighted in the CyberOps Technologies (CBRFIR) 300-215 study guide, understanding behavior and deobfuscating PowerShell scripts is an essential part of the forensic and incident response process.
Specifically:
* During the detection and analysis phase, if PowerShell is used with obfuscated or encoded commands, responders should investigate the intent and behavior of the command.
* Deobfuscation allows analysts to see what the script is doing (e.g., downloading files, creating persistence mechanisms, or opening a reverse shell).
The guide states:
"For example, if the threat is malware, the compromised system should be immediately isolated and the malware should be placed in a sandbox or a detonation chamber to understand what it is trying to do".
This confirms that understanding execution behavior (such as what the PowerShell script intends to perform) is key to uncovering indicators of compromise (IoCs).
Thus, option C-conducting a behavioral analysis and deobfuscating PowerShell-is the most critical and effective response at this stage.