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/").

Reference: CyberOps Technologies (CBRFIR) 300-215 study guide, Chapter on “Understanding Threat

Intelligence Platforms,” including the use of STIX/TAXII for representing threat data.

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.

Reference: CyberOps Technologies (CBRFIR) 300-215 study guide, Chapter: Critical Infrastructure and

Advanced Threat Response, Incident Response Phases for Government Systems.

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.

—

The log entry shows a failed SSH login attempt for an invalid user “admin” from IP 192.168.1.100. 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.

—

If IPS and SIEM logs do not give enough insight into a file's behavior, the next logical step is to review

the Antivirus solution logs. 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 scenario describes an attack vector where insiders or malicious actors use removable 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, using Multi-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.

The error logs indicate multiple PKCS12 and ASN.1 decoding errors, 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:

The private key does not correspond to the certificate being used.

There is a mismatch between 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.

A “malicious insider” is someone within the organization who has authorized access but intentionally

misuses that access to extract or exfiltrate data. In this case:

The HR user has legitimate access but deviates from their normal behavior pattern (accessing legal

data daily instead of monthly).

The presence of large data dumps and the alert from a threat intelligence platform suggest

intentional misuse rather than accidental behavior.

According to the Cisco CyberOps Associate guide, insider threats are identified by behavioral

anomalies, especially involving sensitive data access patterns inconsistent with role-based access

and historical usage profiles.

The Wireshark output shows SMB protocol transactions, including NT Create AndX Response and

Write AndX Response, indicating the transfer of files or objects. SMB (Server Message Block) is a

protocol used for file sharing and printer access in Windows networks. The log does not indicate

phishing or redirection behavior but rather normal SMB communication such as accessing files or

shared resources.

—

According to the CyberOps Technologies (CBRFIR) 300-215 study guide curriculum, command-and-

control (C2) communication is a strong indicator that a system has already been compromised and is

actively under the control of an attacker. Sudden outbound traffic to high-risk regions and resolution

of known malicious domains are high-confidence signs of an active threat. Therefore, prioritizing

detection and disruption of this outbound traffic is critical to prevent further damage or data

exfiltration.

While monitoring vulnerability exploitation (B) and gathering port scan data (D) are also valuable,

they are more preventive or forensic in nature. The most immediate threat—and therefore the top

priority—is stopping active C2 communications.