CAS-004 Security Operations Practice Question
A security analyst is reviewing threat intelligence feeds and notices indicators from a known APT group. Which threat intelligence sharing standard is most commonly used to structure and share such cyber threat information in a machine-readable format?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
STIX/TAXII
STIX (Structured Threat Information Expression) and TAXII (Trusted Automated Exchange of Intelligence Information) are the standard protocols for sharing cyber threat intelligence in a structured, machine-readable format. STIX defines the data model, and TAXII defines the transport mechanism.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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CybOX
Why it's wrong here
CybOX is a schema for characterising observable events and properties, not a complete sharing standard for APT campaign intelligence. It tempts because it is machine-readable and was designed for threat observables, but STIX is the commonly used standard for structuring and sharing cyber threat information.
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MITRE ATT&CK
Why it's wrong here
MITRE ATT&CK is a knowledge base of adversary tactics and techniques, not a sharing standard, so it cannot encode and transport indicators between platforms. It is tempting because it structures threat behaviour for mapping detections; it would be the right choice when categorising an APT's techniques rather than exchanging IOCs.
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STIX/TAXII
Why this is correct
STIX provides a structured, machine-readable schema for describing indicators, threat actors and relationships, while TAXII defines the transport protocol for exchanging that content between servers and clients. Together they satisfy the stem's requirement for a standardised, automated format for sharing APT indicators, unlike document-centric or proprietary feed formats.
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OpenIOC
Why it's wrong here
OpenIOC is a Mandiant indicator format for expressing host-based compromise artefacts, not a sharing standard for structured APT campaign intelligence. It tempts because it is machine-readable and indicator-focused, but STIX is the widely adopted standard for exchanging cyber threat information between platforms.
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