Comprehensive and Detailed Explanation From Exact Extract:

ISO/IEC 27035 strongly encourages information sharing among trusted parties to enhance collective incident response capabilities and reduce the broader impact of cyber threats. Clause 6.5.6 in ISO/IEC 27035-1 highlights the importance of cooperation and communication with external parties, including industry-specific information-sharing forums, CERTs/CSIRTs, and trusted partners.

The practice of proactive information exchange allows organizations to:

Detect coordinated or widespread attacks

Accelerate response through shared indicators of compromise (IOCs)

Benefit from collective intelligence and incident analysis

Build sector-wide resilience

However, such exchanges must occur within well-defined protocols that preserve confidentiality, legal compliance, and operational integrity.

Option B and C reflect overly cautious or siloed approaches that may delay response or reduce the effectiveness of collaborative efforts.

Reference Extracts:

ISO/IEC 27035-1:2016, Clause 6.5.6: “Incident management should consider the importance of trusted collaboration, sharing of incident information, and threat intelligence between relevant entities.”

ENISA and FIRST.org also support this collaborative approach in their best practices.

Correct answer: A

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