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

YARA rulesare primarily used for malware classification and detection based onbinary pattern matchingwithin files. They describe sequences of bytes, strings, and other file characteristics found in malicious binaries.

The Cisco CyberOps Associate guide explains:"YARA rules operate by inspecting binary data using conditions and string matches to identify specific patterns that indicate known malware samples.".

The scenario describes an attack vector where insiders or malicious actors useremovable media (USB drives)to introduce malware, which then connects to external sources to exfiltrate data and compromise systems.

Option B addresses the human factor and technological prevention. The guide stresses the need for training to ensure users are aware of social engineering and removable media risks. Blocking the use of USB drives at a system level further minimizes attack vectors.

Option E, usingMulti-Factor Authentication (MFA), provides an additional layer of defense. Even if credentials are stolen, MFA can prevent the attacker from accessing sensitive internal resources without the second authentication factor.

These controls align with defense-in-depth strategies recommended in the Cisco CyberOps Associate curriculum to combat insider threats and external unauthorized access.

This STIX (Structured Threat Information eXpression) JSON snippet provides two key elements relevant for IOC (Indicator of Compromise) analysis:

The indicator pattern shows a suspicious URL:→ "pattern": "[url:value = 'http://x4z9rb.cn/4712/']" This is the actual IOC that can be used for detection.

The type of object that the indicator relates to:→ "type": "malware"→ "name": "x4z9arb backdoor"This indicates the nature of the threat associated with the IOC is malware.

Therefore, the threat is "malware" and the associated indicator (IOC) is the URL: http://x4z9rb.cn/4712/

Option A correctly captures both the IOC category ("malware") and the indicator value ("http://x4z9rb.cn/4712/").

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 eradication phase in incident response involveseliminating the root cause of the incidentand strengthening defenses to prevent reoccurrence. In this case:

Intrusion Prevention System (D): Adding new rules to the IPS to detect and block malicious activity on TCP/135 is a direct eradication step to remove the threat’s entry point and prevent future attacks.

Centralized User Management (C): Hardening user accounts, removing unnecessary permissions, and applying tighter authentication/authorization measures helps eliminate the possibility that threat actors could exploit weak or mismanaged accounts to continue accessing the system.

Althoughanti-malware software (A)andenterprise block listing (E)are valuable, themost direct eradication stepshere specifically involve managing network access (via IPS) and strengthening user controls (via centralized user management), especially when TCP/135 (MSRPC endpoint mapper) can be used to enumerate services and potentially access vulnerable endpoints remotely.

This aligns with best practices outlined in incident response frameworks (such as the NIST SP 800-61 and referenced resources), which emphasizeclosing the exploited entry points(in this case, TCP/135) andremoving any lingering access pointsthrough user management and network control enhancements.

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.

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.

From the Wireshark capture:

A (iraniansk.com): This domain isnot a known legitimate resourceand is hosting a suspicious file named “Fy.exe,” strongly indicative of amalware distribution domain.

D (Fy.exe): TheContent-Disposition: attachment; filename="Fy.exe"header explicitly signals abinary executabledownload, a key indicator in Emotet campaigns.

WhileContent-Type: application/octet-stream(E) is typical of binary data transfers, it isnot uniqueto malware and cannot by itself serve as a strong IoC. Thenginx server (B)andcookie/hash string (C)similarly do not uniquely indicate compromise.

In cloud environments, investigators typically do not have access to the physical storage devices where the data resides. This restricts traditional forensic processes, such as imaging or direct disk access, which are commonly used in on-premises investigations.

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 provided log file contains multiple HTTP GET requests attempting to access various directories and files on the web server such as:

/balance

/security

/finance

/secret

/opt

/fuzzer/admin

These requests appear to be sequential, systematically targeting commonly used file and directory paths. The response codes are mostly 404 (Not Found) and a few 301s, indicating that the requester is trying different permutations of paths to discover hidden or vulnerable endpoints. This behavior is consistent withdirectory fuzzing, a reconnaissance technique used by attackers (or automated tools) to map out web directory structures by sending a high volume of crafted requests to guess hidden or unlinked directories and files.

This is distinct from DDoS (which would manifest as volume-based access issues), SQL injection (which targets specific parameters within requests), or botnet infection (which generally involves command-and-control communication or massive traffic floods).

Generic Routing Encapsulation (GRE) is a tunneling protocol used to encapsulate a wide variety of network layer protocols inside point-to-point connections. If packets encapsulated with GRE are bypassing monitoring tools, it's likely due to tunneling—where payloads are hidden within another protocol. Tunneling can obscure malicious content or lateral movement in a network and is a common method used in data exfiltration.

In phishing incidents, especially with successful lateral movement (land and expand), the most critical factor is usuallyweaknesses in email security systems—such as lack of advanced phishing detection, weak DMARC/DKIM/SPF policies, or insufficient user behavior monitoring. To prevent recurrence, the root cause analysis must focus on what allowed the phishing email to bypass defenses and how initial credentials were compromised.

This aligns with best practices from the Cisco CyberOps v1.2 Guide underEmail Threat Vectors and Security Control Weaknesses.

Volatility is an open-source memory forensics tool specifically designed for memory analysis. It allows forensic investigators to inspect memory dumps for running processes, hidden processes, injected code, and malicious activity in memory.

As per the Cisco CyberOps Associate study guide, “Volatility helps security professionals with both incident response and malware analysis. It can identify processes, registry artifacts, network connections, and memory-resident malware”.

While Memoryze (D) is also a memory analysis tool, Volatility is the more recognized, command-line driven tool used widely in industry and is directly highlighted in the curriculum.

The string shown is long, alphanumeric, and includes both uppercase and lowercase letters with numbers—characteristics of Base64 encoding. This format is widely used to obfuscate payloads in malicious scripts, particularly in phishing or malware campaigns. Base64 encoding is also supported by Python and other platforms for data transformation.

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The most relevant log for system-level events such as memory exhaustion and shutdown is/var/log/messages.log, which contains kernel and service-level logs including OOM (Out-Of-Memory) events.

As detailed in Linux investigations:

"Logs located in/var/log/messagesprovide critical system error reporting including shutdowns, memory errors, and service failures".

Process Explorer is an advanced Windows-based utility that shows real-time data about running processes, CPU usage, services, DLLs, and handles. It is specifically designed for this kind of investigation and is part of the Sysinternals Suite.

In highly sensitive environments such as secure government networks, the presence of anomalous DLL injection, beaconing to known interception points, and signs of encrypted data exfiltration constitutes a critical incident. The appropriate response in such classified contexts involves:

Invoking a pre-established, classified incident response protocol,

Immediately notifying national cyber defense operatives (such as national CERT or military cyber command),

Prioritizing containment to stop lateral spread,

Proceeding with eradication of malware or backdoors.

This response sequence aligns with the high-severity, immediate-response model described in the Cisco CyberOps Associate v1.2 curriculum under national defense and classified incident frameworks. The study guide emphasizes the importance of stakeholder communication and multi-agency coordination during advanced persistent threat (APT) intrusions involving critical infrastructure or defense systems.

Comprehensive and Detailed Explanation:

The log entries show repeated SSH login attempts for various invalid usernames (e.g., admin, phoenix, rainbow, test, user, etc.) from different source ports. These are clear signs of a brute-force attack—an automated process trying multiple usernames and passwords in hopes of gaining access.

Mitigating such attacks includes:

Implementing account lockout policies (e.g., locking an account after several failed login attempts).

Enabling Multi-Factor Authentication (MFA) to ensure that password guessing alone is insufficient for account access.

Therefore, the correct answer is:

D. Brute-force attack; implement account lockout policies and roll out MFA.

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 key goal during lateral movement analysis is to determine whether the malware spread or attempted to spread beyond the initially compromised system. This is crucial for containment and scoping of the incident. Logs, sandbox behavior, or network activity may show if Patient 0 initiated outbound connections to other systems, potentially propagating malware across the environment.

Correct answer: D. if Patient 0 tried to connect to another workstation.

The metadata in the exhibit reveals a strong indicator that this .LNK file (shortcut) is malicious:

The shortcut file is named "ds7002.pdf" but actually points to the execution of PowerShell:→ Full path: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe

Arguments include:→ -noni -ep bypass $z = '...'; indicating an attempt to run a PowerShell script with execution policy bypassed (a known tactic for fileless malware delivery).

The file is masked as a PDF (common social engineering technique), and PowerShell execution via .LNK is a signature technique used by many malware families to initiate second-stage payloads or scripts.

Given this, the correct and safest course of action is to:

→ Open the .LNK file in a sandbox environment (D).

This enables safe behavioral analysis to observe what actions it attempts upon execution without endangering live systems.

Other options are inappropriate:

A (ignoring the threat due to extension) is dangerous — .LNKs can trigger code.

B (upload to virus engine) is only helpful for known malware and lacks behavioral context.

C (quarantine) is preventive but not investigative — sandboxing provides visibility.

The error logs indicate multiplePKCS12andASN.1 decodingerrors, such as:

PKCS12 routines:PKCS12_parse:mac verify failure

rsa routines:old_rsa_priv_decode:RSA lib

PKCS12 routines:PKCS12_key_gen_uni:malloc

These specific errors most commonly occur when:

Theprivate key does not correspondto the certificate being used.

There is amismatchbetween the public and private key pair required for SSL handshakes.

This is a well-documented condition in Apache SSL configuration issues and explicitly covered under TLS/SSL troubleshooting sections in cybersecurity operations contexts. The Cisco CyberOps guide also notes that SSL errors with key verification usually result from "improper key/certificate pairing" rather than file corruption or missing modules.

Thus, the correct answer is:

B. The private key does not match with the SSL certificate.

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.

Since the phishing email originates from a known compromised cloud provider (XYZCloud), the correct immediate action for the security analyst is to determine the broader scope of exposure. This involves checking whether other users in the organization received similar emails from the same potentially malicious source. Therefore, querying for emails from theIP address rangesorSMTP domainslinked to XYZCloud is essential for identifying other possible attack vectors.

This step aligns with the containment phase of the incident response lifecycle, as outlined in theCyberOps Technologies (CBRFIR) 300-215 study guide, where threat hunting and log analysis are used to determine the extent of compromise and prevent lateral movement or further exposure. Only after the scope is understood should remediation or reporting actions follow.

According to the Cisco CyberOps Associate guide, the goal of a root cause analysis is to determine how an attacker successfully exploited a system so that similar vulnerabilities can be mitigated in the future. The "method of infection" (e.g., phishing email with malicious attachment, drive-by download, credential compromise, etc.) is the most relevant factor in understanding the initial access vector and subsequent spread of ransomware across the network.

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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 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.

Comprehensive and Detailed Explanation:

From the exhibit, Cisco Secure Malware Analytics (formerly Threat Grid) has captured outbound HTTP POST communication to the IP address 51.38.124.206 on port 80. This destination is highlighted in the analysis under “Outbound HTTP POST Communications,” indicating exfiltration behavior or command-and-control (C2) signaling.

Key indicators:

The report shows that binary data was POSTed to this IP.

The source system generated 22 packets and sent 6,192 bytes.

The system has flagged the behavior with a severity of 25 and confidence of 25—suggesting that this is an IoC worth acting on.

Therefore, the artifacts suggest that the destination IP 51.38.124.206 is involved in malicious activity, and the correct answer is:

Answer: A. Destination IP 51.38.124.206 is identified as malicious.

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 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.