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The log entry shows a failed SSH login attempt for an invalid user “admin” from IP192.168.1.100. As the system has just gone live and no legitimate use is expected, this could be an early reconnaissance or brute-force attempt. However, blocking IPs or resetting passwords without fully understanding the context could lead to incomplete remediation or false positives.

According to Cisco CyberOps best practices, the first step is to thoroughly investigate the alert by correlating it with other logs (e.g., authentication logs, IDS/IPS logs) to determine the intent and scope of activity.

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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 theCyberOps 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.

This scenario describes asubstitution cipher, where data is made unreadable or less recognizable without altering its functionality. According to the Cisco CyberOps Associate guide, obfuscation includes techniques such as shifting, encoding, and symbol manipulation to mask the true nature of data or code:

"A very well-known cipher, the Caesar cipher... shifts the letter of the alphabet by a fixed number... This technique is a form of data obfuscation used to bypass detection mechanisms.".

Theroot cause analysisin incident response focuses on identifying theinitial trigger or root causeof the incident to understand how it started and how to prevent recurrence. In this scenario, thephishing email sent to the victim(A) is the initial trigger that led to the employee’s action of clicking the malvertising link, resulting in the malware download.

The other options represent later stages in the incident response cycle, such as detection (SIEM alert, cybersecurity team’s alert) or supporting evidence (email header information), but they do not address the root cause, which is thephishing email itself.

This aligns with theCyberOps Technologies (CBRFIR) 300-215 study guide, which states that identifying theinitial vector of compromiseis critical to theroot cause analysisphase of incident response (Chapter: Incident Response Techniques, page 410-412).

The safest and most effective approach is to isolate the files and subject them to heuristic and behavioral analysis. This can reveal obfuscated malware or unauthorized data storage techniques, even if signature-based antivirus fails to flag them.

The alert clearly identifies ET SCAN DirBuster Web App Scan in Progress, referencingSID 2008186, which is a Snort signature that specifically detectsDirBusteractivity. DirBuster is a well-known tool used for brute-forcing hidden directories and files on web servers.

The Cisco CyberOps Associate guide and OWASP both identifydirectory brute-forcingas a reconnaissance technique to find unprotected or misconfigured endpoints on web applications, typically prior to launching deeper attacks.

Therefore, the correct interpretation of the alert is:

C. brute-force attack against directories and files on the target webserver.

The Apache access logs in the exhibit show a sequence of HTTP requests and responses indicative of a malicious upload via WordPress:

A POST to:

/wp-admin/admin-ajax.php with parameters that include uploading r57.php (a known PHP web shell).

The uploaded file name appears as r57.php in:→ &name=%5B%5D=r57.php&FILES...

There are plugin installation and activation attempts, specifically for:

file-manager plugin:→ plugin=file-manager&...

Which is known to be vulnerable and exploited for file uploads.

GET requests to:

/wp-content/57.php and variations such as 57.php?28 — This suggests that r57.php was successfully uploaded and is being accessed.

These logs reveal that:

D. The attacker used the WordPress file manager plugin to upload r57.php — confirmed by plugin activity and file uploads.

B. The attacker uploaded the WordPress file manager trojan — as evidenced by the direct access to /wp-content/57.php (r57 shell variant).

Other options are invalid or speculative:

A is correct in identifying r57 as a web shell, but the logs don't show privilege escalation.

C mentions brute force and SQL injection, which are not indicated here.

E assumes legitimate access — logs suggest exploitation, not standard login.

The exhibit shows a series of process executions that form a suspicious chain involving scripting engines and obfuscated commands:

One critical indicator iscmd.exe executing PowerShell with obfuscated (Base64-encoded) arguments. The use of Base64 is a known method used by attackers to mask malicious commands. This aligns with attack techniques defined under MITRE ATT&CK T1059 (Command and Scripting Interpreter) and T1086 (PowerShell abuse). Therefore, option D is valid.

Another important IOC isWScript.exe acting as a parent of cmd.exe, which is abnormal in typical business environments. This indicates potential misuse of Windows Script Host (WSH) to launch commands, often seen in phishing or malware dropper scenarios. Thus, option E is also valid.

Options A and B by themselves are not definitive IOCs—PowerShell and cmd.exe are legitimate administrative tools and frequently used in Windows environments.

Option C is not supported by the exhibit—the reverse (powershell.exe initiated by WScript.exe) is what's seen, not the other way around.

These patterns align with theCyberOps Technologies (CBRFIR) 300-215 study guide, which specifies that chaining of interpreters (e.g., WScript → cmd → PowerShell) with encoded commands is a key indicator of compromise during forensic analysis.

The best immediate step during a DDoS attack against an Apache web server is to inspect theaccess logs, which will show which IP addresses are making requests, their frequency, and potential patterns of abuse. As covered in the Cisco CyberOps material, "Apache logs can reveal the IPs responsible for flooding the service with requests". The commandsudo tail -100 /var/log/apache2/access.logallows quick review of recent activity.

The observed process tree (AcroRd32.exe→cmd.exe→powershell.exe) strongly suggestsmalicious behavior, particularly inPDF-based malware attacksleveraging embedded scripts or exploits.

Ais correct: Submitting the suspicious PDF toCisco Threat Gridallows sandbox analysis to detect hidden malicious behaviors.

Dis correct: The suspicious activity warrantsquarantining the hostto contain potential spread or further compromise.