300-215 Conducting Forensic Analysis and Incident Response Using Cisco CyberOps Technologies (CBRFIR) Questions and Answers

Fileless malwareoperates in memory and often leverages legitimate tools such asPowerShellto avoid traditional file-based detection. Since these threats don't leave typical file traces, analysts must rely onPowerShell event logsto trace suspicious or unauthorized script execution.

The Cisco CyberOps Associate guide explicitly states:

“PowerShell logs provide insight into script block execution and can reveal indicators of fileless attacks that reside in memory.”

Hence,PowerShell event logsare the most effective forensic source for detecting fileless malware activity on Windows systems.

During the initial phase of incident response, the two key actions are:

Disconnecting the server (B) to contain the threat and prevent lateral movement or further exfiltration.

Reviewing network logs (E) to understand the timeline and scope of the attack.

These are emphasized in the containment and detection stages of the incident response lifecycle outlined in NIST 800-61 and covered in the Cisco CyberOps training.

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The magic number (also known as a magic byte) is a sequence of bytes used to identify the format of a file. For PDF files, the standard magic number is:

25 50 44 46, which translates to%PDFin ASCII. OptionC(255044462d) begins with25 50 44 46, confirming it's a PDF file signature. This is a key forensic detail when performing file type identification and validation of potentially obfuscated or renamed files.

The Python code snippet:

Usessocket.socket(AF_INET, SOCK_STREAM), which indicatesTCP communication

Connects to a remote server (192.168.1.10on port 80)

Sends a manual HTTPGETrequest

Receives the response usings.recv()

This is a classic example ofTCP/IP socket programming, specifically creating asimple TCP clientto communicate with a web server. It does not monitor traffic or crawl websites — it sends a crafted request and prints the response.

Thus, this code best fits:

D. socket programming listener for TCP/IP communication.

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.

The XML structure shows that:

The file namestarts with:"Final Report"

The file extensionequals:"doc.exe"

Together, this forms"Final Report.doc.exe"— a knowndouble-extensiontechnique used todisguise executablesas benign documents. This is a red flag in email forensics, commonly linked tomalware distribution, and explicitly covered in the Cisco CyberOps study material as a typicalevasion methodfor malicious attachments.

To determine the correct script, we evaluate the following requirements:

The script must search for the IP address 192.168.100.100.

The output should be written to a file named parsed_host.log.

The matching lines should be printed to the console.

Analysis of the options:

Option A: Correct IP regex used and correct output filename, but reads from parsed_host.log instead of a source log file like test_log.log (not ideal for initial parsing).

Option C: The IP address used is 192.168.100.101 instead of 192.168.100.100 — incorrect.

Option D: Same IP address and logic as Option B, but uses print statement without parentheses, which is not valid in Python 3 unless using Python 2 — not ideal.

✅Option B:

Uses correct IP: "192.168.100.100"

Reads from test_log.log (presumably the source log file).

Writes to output/parsed_host.log.

Prints each matching line and writes to output file — satisfying all conditions.

If IPS and SIEM logs do not give enough insight into a file's behavior, the next logical step is to review theAntivirus solutionlogs. These logs often provide detailed behavior analytics such as:

File actions and access patterns

Registry modifications

File execution history

The Cisco CyberOps guide emphasizes AV logs as critical forensic artifacts for understanding endpoint-based infections, especially when beaconing or suspicious activity is suspected.

The string in the exhibit is a classic example of Base64 encoding. Base64 is used to encode binary data into ASCII characters, making it suitable for transmitting data over media that are designed to deal with textual data. It typically ends with one or two equal signs=(padding), which this string does. This format is commonly seen in obfuscated payloads or malware communications in the wild.

TCPdumpis a CLI-based packet capture tool that is widely used for real-time traffic inspection and analysis on Unix/Linux systems.

TCPsharkis a variant CLI tool used similarly for packet analysis.

AlthoughWiresharkis a powerful network protocol analyzer, it requires a GUI. Therefore, it is not suitable for environments without a graphical interface.

The-hoption in theobjdumpcommand displayssection headersof an object file. According to general usage and command-line documentation, and also explained in digital forensics tools discussions in the CyberOps course, the header information includes details about the name, size, VMA, LMA, file offset, and alignment of each section in the object file. This helps analysts understand how data is stored and organized within compiled files during forensic examinations.

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.

TCPdump is a command-line packet analyzer used to capture and inspect network packets. As described in the study guide, "tcpdump is a command-line interface tool that is used to capture packets on a network. It is a very powerful and popular network protocol analyzer". The tool allows cybersecurity professionals to analyze headers and payloads of network traffic, making it valuable in forensic investigations and network diagnostics.

Cisco Firepower Management Center (FMC), when configured with Snort rules, classifies attacks with signature categories such as FILE-OFFICE for Microsoft Office-based exploits. One of the critical threats involving Microsoft Office is a known vector involving Microsoft Graphics, which attackers exploit forremote code execution (RCE). RCE vulnerabilities enable attackers to execute arbitrary commands or code on the target machine—making this classification high-severity.

The alert "FILE-OFFICE Microsoft Graphics remote code execution attempt" is consistent with what Cisco and Snort define for such threats and appears in rulesets addressing vulnerabilities like CVE-2017-0001.

The described scenario includes both internal alerts (unusual network traffic, failed logins, suspicious file access) and external intelligence indicating active ransomware campaigns in the same industry. This constitutes a strong combination of precursors and indicators, as defined in the NIST SP 800-61 incident handling model and reinforced in the Cisco CyberOps Associate curriculum.

According to the Cisco guide:

“Once an incident has occurred, the IR team needs to contain it quickly before it affects other systems and networks within the organization.”

“The containment phase is crucial in stopping the threat from spreading and compromising more systems”.

Given these indicators and the high-value nature of the data involved, it is essential to proactively isolate suspected systems and activate the incident response plan to prevent damage from potential ransomware.

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The exhibit shows multipleARP reply packetswith the same IP addresses (192.168.51.105and192.168.51.201) being mapped todifferent MAC addresses, which triggers the message: "duplicate use of [IP] detected". This is a strong indicator of anARP spoofing(or poisoning) attack.

ARP spoofing occurs when a malicious actor sends falsified ARP messages to associate their MAC address with the IP address of another host. This misleads other devices on the network and allows interception or redirection of traffic.

The Cisco CyberOps Associate guide specifically recommendsconfiguring port securityon switches as a method tomitigate ARP spoofing, by limiting the number of MAC addresses allowed per port or statically assigning legitimate MAC addresses to switch ports.

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 goal of an incident response plan (IRP) is to provide structured procedures for responding to cybersecurity incidents in a way that limits damage, contains the threat, and ensures business continuity. As outlined in the NIST SP 800-61 and Cisco CyberOps Associate study guide, containment and minimizing the impact of incidents is the primary goal of an IRP.

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The command in the image usesschtasks /createwith theONLOGONschedule andSystemuser context to executetest.exe. This is a well-documented persistence technique, where an attacker ensures that a malicious executable is launched automatically at each system logon. This kind of scheduled task creation aligns with persistence techniques in the MITRE ATT&CK framework (T1053).

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YARA rulesare designed to identifyfilesthat match specific patterns, strings, or binary characteristics.

The Cisco CyberOps guide states:

“YARA helps researchers and analysts identify and classify malware samples based on textual or binary patterns”.

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.

One of the primary concerns when gathering forensic evidence in public cloud environments is the issue of multitenancy. In a shared cloud infrastructure, multiple tenants (organizations or users) operate on the same physical hardware, using virtualization to logically separate resources. This architecture poses a significant challenge for forensic investigations because:

Forensic investigators must ensure that they do not inadvertently access or expose data belonging to other tenants while collecting evidence.

This can limit access to low-level system data or hardware-level logs that might be essential for a thorough forensic analysis, since providers must enforce strict data isolation policies.

This concern is recognized in industry practices and guidelines, including NIST SP 800-86, which underscores the need to collect data in a forensically sound and legally defensible manner—something made more complex in shared environments.

The Cisco CyberOps Associate guide emphasizes the challenges of evidence handling in cloud environments, stating that "gathering evidence in the cloud must be carefully performed to ensure compliance with legal standards and to respect the boundaries of other tenants' data".

The XML (STIX/CybOX format) details anemail-based threatindicator. Specifically:

Theemail addresscontains “@state.gov” (not exact match, so blocking all @state.gov would be overbroad).

Theattachment is a PDFfile with a specifiedMD5 hash: cf2b3ad32a8a4cfb05e9dfc45875bd70.

Theattachment sizeis 87022 bytes.

From a threat mitigation perspective:

Ais correct: Updating AV to block or flag files matching the malicious hash is a standard response.

Dis correct: The email address context and hash together provide a precise rule for blocking—this prevents false positives.

Incorrect options:

Boverreaches by blocking an entire domain without confirming threat context.

Cwould stop all PDFs, which is impractical.

Eis incorrect; there is no indication that the hash appears in the subject line.

In VMware ESXi systems, the vmksummary.log file is responsible for capturing general system events, including uptime, reboot statistics, and key service-related issues. It serves as a valuable source for troubleshooting persistent or unexplained system behaviors.

The Cisco CyberOps study guide references log file paths used in system diagnostics and incident response, and for authentication-related issues on ESXi where standard logs don't yield insights, vmksummary.log is the recommended next source for identifying systemic service faults or anomalies.

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The first and most important step in forensic analysis is to preserve the integrity of the data. According to best practices outlined in the Cisco CyberOps Associate guide and NIST 800-86, forensic investigators must first produce a forensically sound, bit-by-bit copy of the system’s data (i.e., imaging). This enables analysis to occur without altering the original evidence, which is essential for legal admissibility and maintaining the chain of custody.

The correct registry path to investigate user profiles and login details is:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\ProfileList

This location stores information about each user profile on the machine, including login activity and the LastWrite time for forensic tracking.

The code in the exhibit is written in Python. Here’s how we can confirm:

The function definition uses Python syntax: def function_name(args):

It uses the b64encode and decode functions — typical of Python’s base64 module.

Data structures such as dictionaries are used with curly braces (e.g., form_data = {entry1: enc1, ...}).

The conditional syntax uses “if r.status_code == 200:” which is Pythonic.

The request object “r = post(...)” and use of headers show standard use of the Python requests library.

This type of script is typical in exfiltration scenarios where encoded information is sent via a web form (in this case Google Forms), bypassing detection systems.

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.

Once an incident has occurred, the appropriate course of action is to engage the organization's Incident Response (IR) plan. This is a structured approach to contain, analyze, and eradicate threats before they spread across the network.

The Cisco CyberOps Associate study guide emphasizes:

“Incident response and handling are essential within an organization… The main objective of implementing an incident handling process is to reduce the impact of a cyber-attack, ensure the damages caused are assessed, and implement recovery procedures”.

In particular, the containment phase of IR is focused on isolating the threat and preventing lateral movement or further compromise.

Options such as "root cause" or "attack surface" are relevant at later stages of analysis and mitigation, not immediate containment. Therefore, the correct answer is C.