RS.CO-03: Information is shared with designated internal and external stakeholders

RS.CO-03 requires you to consistently share cybersecurity response information with pre-designated internal teams and external parties (as appropriate), using defined triggers, approved channels, and clear ownership. To operationalize it fast, publish a stakeholder communication matrix, integrate it into incident response workflows, and retain evidence that the right people received the right updates on time. ¹

Key takeaways:

• Pre-designate who gets what information, when, and through which channels; don’t decide during an incident. ¹
• Build communications into response playbooks with explicit triggers, approvals, and alternates. ²
• Keep defensible evidence: distribution lists, message templates, logs, and post-incident reviews that confirm sharing happened. ¹

The rs.co-03: information is shared with designated internal and external stakeholders requirement is a response communications control. It’s about making stakeholder information-sharing routine, pre-planned, and auditable, not heroic. In practice, organizations fail this requirement less because they never communicate, and more because communications are ad hoc: the wrong people are left out, messages go out through unapproved channels, legal and comms review is inconsistent, and there’s no evidence trail after the fact.

RS.CO-03 sits in the “Respond” function and the “Communications” category of NIST CSF 2.0, so auditors and assessors tend to evaluate it through the lens of operational readiness: do you have a defined plan, does the plan map to real stakeholders, does it actually run during incidents, and can you prove it. ¹

This page gives requirement-level implementation guidance you can execute quickly: scope, roles, workflows, artifacts, and an execution plan you can run as a CCO, GRC lead, or compliance owner partnering with Security, Legal, Privacy, and Communications.

Regulatory text

Excerpt: “Information is shared with designated internal and external stakeholders.” ¹

What an operator must do:

1. Designate stakeholders in advance (named roles, teams, and external parties as applicable). ¹
2. Define what “information” means for your organization (incident facts, status, business impact, containment actions, customer impact, regulatory implications, and requests for assistance). ²
3. Embed sharing into your response process with triggers, approvals, channels, and backups so it happens reliably under pressure. ¹
4. Maintain evidence that communications occurred per the designations and process. ¹

Plain-English interpretation

RS.CO-03 means you have a repeatable way to notify and update the right internal leaders and external parties during cybersecurity events. “Designated” is the operative word: you pre-decide recipients, escalation paths, and communication methods, then follow them during real incidents and exercises. ¹

Who it applies to

Entity scope: Any organization running a cybersecurity program, including regulated and non-regulated organizations adopting NIST CSF 2.0 as their control framework. ¹

Operational context (where this control is tested):

• Security incident response (malware, intrusion, data exposure, DDoS, account takeover)
• Major system outages with suspected cyber cause
• Third-party incidents that affect your environment or customers (cloud/SaaS outage, supplier breach)
• Coordinated vulnerability disclosure and exploitation events (internal discovery or external notification)
• Crisis management involving executives/board and business continuity teams

Stakeholders typically in scope (tailor to your org):

• Internal: SOC/IR, IT Ops, CISO, CIO/CTO, Legal, Privacy, Compliance, Risk, HR (if employee impact), Finance (fraud), Product, Customer Support, Execs, Board liaison.
• External: key third parties (critical suppliers), incident response retainer, outside counsel, cyber insurance broker/carrier, affected customers (if applicable), sector sharing groups (if you participate), law enforcement (as directed by Legal).
  RS.CO-03 does not force disclosure to every external party; it requires that external stakeholders you intend or may need to communicate with are designated, and communications are governed. ¹

What you actually need to do (step-by-step)

1) Assign ownership and decision rights

• Control owner: usually IR program owner (Security) with GRC/Compliance as oversight.
• Approvers: Legal (privilege and liability), Privacy (regulated data considerations), Communications/PR (external statements), Security leadership (technical accuracy).
• Backup roles: named alternates for each approver to avoid “single point of approval failure.”

Deliverable: RACI for incident communications and stakeholder notification.

2) Build a stakeholder communication matrix (the core artifact)

Create a table that answers, for each incident severity level/type:

Trigger	Internal recipients	External recipients	Channel	Approval required	Max lag target (internal)	Evidence source
Confirmed incident (any)	IR on-call, IT Ops	IR retainer (if contracted)	Ticket + secure chat	IR lead	“Immediate”	Ticket log, chat export
Suspected customer impact	Exec on-call, Legal, Privacy, Support lead	Draft holding statement recipients	Email + crisis bridge	Legal + Comms	“Same business day”	Email headers, bridge notes
Third-party incident affecting services	Vendor/TPRM lead, Service owner	Affected third party contact	Email + portal	Legal (if needed)	“As soon as validated”	Portal logs, email thread

Notes:

• Use “max lag targets” as internal SLAs you set; they’re governance commitments, not regulatory numbers.
• Define approved channels (secure ticketing, encrypted email, crisis bridge) and explicitly ban informal channels for external comms if that’s your policy.

Deliverable: Communication Matrix v1.0, approved and version-controlled. ¹

3) Standardize message content with templates

Develop templates that reduce rework and errors:

• Internal incident update template: what happened, when detected, current status, affected systems, business impact, actions taken, asks/decisions needed, next update time.
• External notification template (if used): plain language description, what you know/don’t know, customer actions, where to route questions, commitment to updates, reference ID.
• Third-party coordination template: request for indicators of compromise, logs, timelines, containment steps, and a named point of contact.

Deliverable: Template pack stored in your IR knowledge base, with Legal/Comms-approved language blocks. ²

4) Integrate communications into incident workflows (don’t leave it in a policy binder)

Put required tasks directly into:

• IR playbooks (ransomware, BEC, data exposure, third-party outage)
• Ticketing workflows (mandatory fields: “stakeholders notified,” “time notified,” “method”)
• On-call runbooks (who to page; escalation tree)
• Crisis management bridge procedures (cadence of updates, scribe responsibilities)

Deliverable: Updated playbooks and workflow checklists showing where RS.CO-03 communications steps occur. ¹

5) Test it via tabletop exercises and operational drills

Run exercises that force real decisions:

• An incident that starts technical and becomes customer-facing
• A third-party event where your provider is slow to respond
• A scenario requiring executive approval for external statements

Deliverable: Exercise agenda, attendance, after-action report noting communication gaps and remediation owners. ¹

6) Operationalize evidence collection (so audits are boring)

Set a recurring evidence routine:

• For each qualifying incident: export ticket timeline, notification log, email headers, and bridge notes.
• For each exercise: store the AAR and action tracker.
• For distribution lists: retain change history and quarterly review attestations (your own governance cadence).

Deliverable: Evidence register mapped to RS.CO-03, with location, owner, and retention period aligned to your policy. ²

7) Make third-party communications explicit

Because external stakeholders often include third parties:

• Confirm primary/backup contacts for critical third parties (TPRM can maintain).
• Pre-negotiate incident cooperation expectations in contracts (points of contact, response times, info sharing mechanisms).
• Align internal and external statements to avoid contradictions.

Deliverable: Critical third-party contact roster + contract clause library for incident cooperation (where feasible). ¹

Required evidence and artifacts to retain

Maintain a minimum set that proves design + operation:

Design evidence

• Incident Communications Policy/Standard referencing designated stakeholders. ¹
• Stakeholder Communication Matrix (version-controlled, approved). ²
• RACI for approvals and spokesperson authority. ¹
• Approved message templates and channel standards. ¹

Operating evidence

• Incident tickets showing notification tasks completed (timestamps, recipients, channel). ¹
• Email headers or messaging exports for key notifications (redact sensitive content as needed, but keep metadata). ¹
• Crisis bridge minutes/scribe notes and executive briefings. ²
• Tabletop exercise AARs and remediation tracker. ¹

Common exam/audit questions and hangups

1. “Show me your designated stakeholders.” Auditors want a named matrix, not “we notify as needed.” ¹
2. “How do you decide when to communicate externally?” They expect triggers tied to incident classification and legal/privacy review points. ¹
3. “Prove it happened.” They will pick a recent incident and trace the comms trail end-to-end. ²
4. “What about third-party incidents?” Expect questions about supplier notification paths and how you coordinate information exchange. ¹
5. “How do you prevent inconsistent messaging?” Look for templates, approvals, and a single source of truth (ticket/bridge notes). ¹

Frequent implementation mistakes and how to avoid them

• Mistake: “Designated stakeholders” is a shared mailbox.
  Fix: name roles and alternates; map to distribution lists with owners and change control. ¹

• Mistake: External stakeholders aren’t pre-approved.
  Fix: pre-list likely external parties (carrier, outside counsel, IR firm, key suppliers) and define who can contact them. ¹

• Mistake: Communications are “done,” but there’s no evidence.
  Fix: make the incident ticket the system of record with mandatory fields and attach exports. ²

• Mistake: Legal review blocks speed because it’s bolted on.
  Fix: create pre-approved language blocks and a lightweight approval workflow with alternates. ¹

• Mistake: Third-party notifications are improvised.
  Fix: maintain a critical third-party contact roster through TPRM and confirm it on a governance cadence you can defend. ¹

Enforcement context and risk implications

NIST CSF is a framework, not a regulator. RS.CO-03 still matters because many regulatory exams, customer security reviews, and cyber insurance underwriting processes test incident communications maturity against recognized frameworks, including NIST CSF. Failing RS.CO-03 typically shows up as delayed escalation, inconsistent external messaging, and weak incident records, which then amplifies legal, operational, and reputational risk during a real event. ¹

Practical 30/60/90-day execution plan

First 30 days (stabilize the minimum viable control)

• Assign control owner and approvers; document RACI.
• Draft Stakeholder Communication Matrix for top incident types; get Security, Legal, Privacy, and Comms sign-off.
• Standardize one internal update template and one external draft template (even if you rarely send it).
• Update IR ticket workflow to require “stakeholders notified” fields and timestamps.

Days 31–60 (make it operational and testable)

• Embed comms steps into top playbooks and on-call runbooks.
• Stand up or clean up distribution lists; assign list owners and change control.
• Run a tabletop exercise focused on stakeholder updates and approvals.
• Build an evidence register for RS.CO-03 and run a mock audit on a past incident.

Days 61–90 (scale and harden)

• Extend the matrix to third-party incident scenarios and critical supplier contacts.
• Add crisis-bridge procedures (scribe, update cadence, decision log).
• Close tabletop findings with tracked remediation and owners.
• If you use a GRC platform like Daydream, map RS.CO-03 to your policy, procedure, control owner, and recurring evidence collection so audits pull from one place instead of email archaeology. ²

Frequently Asked Questions

Does RS.CO-03 require notifying regulators or customers?

RS.CO-03 requires sharing information with designated internal and external stakeholders, but it doesn’t specify who those stakeholders must be. Your design should align to your legal, privacy, and contractual obligations and document the triggers and approvers for any external notifications. ¹

Who should “designate” the stakeholders: Security or Compliance?

Security usually owns incident response operations, while Compliance/GRC ensures the designation is documented, approved, and evidenced. The cleanest model is Security as control owner with Legal/Privacy/Comms as required approvers and GRC as oversight. ¹

What evidence is strongest in an audit?

Auditors like time-stamped artifacts that show who was notified, when, and through what channel, tied to an incident record. Ticket exports, bridge notes, and approved distribution lists beat informal screenshots and recollections. ²

How do we handle sensitive details and privilege?

Separate technical collaboration from executive and external messaging, and route sensitive narratives through Legal-approved channels and templates. Keep the incident ticket factual and control access, while preserving enough metadata to prove communications occurred. ¹

We have global teams. Do we need different stakeholder lists by region?

Create a global baseline matrix, then add regional overlays where legal, privacy, or customer communications differ. The key is that recipients and approvals remain pre-designated and the workflow tells responders which list applies. ¹

How does this connect to third-party risk management?

External stakeholders often include critical third parties and incident response partners, so RS.CO-03 works best when your TPRM program maintains current contacts and incident cooperation expectations. Treat supplier notification as a defined playbook step with evidence captured in the same system of record. ¹

Footnotes

1. NIST CSWP 29

2. NIST CSF 1.1 to 2.0 Core Transition Changes