Signs of an Incident

The “signs of an incident” requirement means you must continuously monitor for both precursors (signals an incident may be coming) and indicators (signals an incident is happening or happened) using security tool alerts, log sources, public information, and human reports. You operationalize it by defining what to monitor, centralizing detection inputs, triaging consistently, and retaining evidence that your monitoring actually runs. ¹

Key takeaways:

• Monitor both precursors and indicators across tools, logs, public intel, and internal/external reporting channels. ¹
• “Having tools” is not enough; you need defined signal coverage, triage rules, escalation paths, and proof of operation. ¹
• Evidence should show inputs → detection/alert → triage decision → escalation/closure, plus monitoring health and gaps.

CCOs and GRC leads often get pulled into incident response late, after technical teams have already labeled something a “security incident.” NIST SP 800-61 Rev 2 Section 3.2.2 pushes the work earlier: detect the signs before they become an uncontrolled event. The requirement is operational, not philosophical. You need to know which signals count, where they come from, who reviews them, how quickly they get triaged, and what you retain to prove monitoring happened.

The practical challenge is coverage sprawl. Alerts live in endpoint tools, cloud consoles, identity providers, email gateways, and network devices. Logs may exist, but not be reviewed. Employees report suspicious activity, but the reports go to the wrong inbox. Third parties may notify you of an issue, but there is no intake process to treat those reports as incident indicators. This page translates the requirement into a monitoring and triage operating model you can stand up, test, and defend in an audit using clear artifacts. ¹

Regulatory text

NIST SP 800-61 Rev 2, Section 3.2.2: “Monitor precursors and indicators of incidents through alerts from security tools, logs, publicly available information, and reports from internal or external sources.” ¹

Operator interpretation (what you must do):

• Establish monitoring that covers precursors (early warning signals) and indicators (evidence an incident is occurring or occurred). ¹
• Use multiple channels of detection input: security tool alerts, log monitoring, publicly available information, and internal/external reports. ¹
• Make monitoring actionable: inputs must flow into a defined triage process so the organization can decide whether to escalate into incident handling. ¹

Plain-English interpretation

You must be able to answer, with evidence: “How do we know something bad is starting or has started, and how do we catch it?” This includes:

• Automated signals (IDS/IPS, EDR/antivirus, SIEM correlations).
• Manual signals (a developer reports leaked credentials; a third party tells you your data is for sale; a customer reports account takeover).
• Public signals (vulnerability disclosures relevant to your environment; credible reports of active exploitation). ¹

Who it applies to

Entity scope: Organizations, including U.S. Federal agencies, and any organization adopting NIST SP 800-61 as incident handling guidance. ¹

Operational scope (where this shows up):

• Security operations / IT operations: alerting, logging, monitoring health.
• GRC and compliance: defining minimum monitoring expectations, evidence, and testing.
• Engineering and cloud teams: ensuring security logs exist and are accessible.
• HR, Legal, and Privacy: intake of human reports and third-party notifications that may indicate an incident.
• Third-party risk management: handling incident-related notifications from third parties as monitored inputs (external source reports). ¹

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

1) Define “precursors” and “indicators” for your environment

Create a short, approved list that teams can use consistently.

• Precursors (may occur): unusual authentication patterns, newly disclosed vulnerabilities affecting your stack, anomalous outbound connections, spikes in blocked email, repeated privilege escalation attempts.
• Indicators (occurring/occurred): confirmed malware execution, confirmed unauthorized access, exfiltration evidence, unauthorized changes to IAM policies, integrity failures in critical systems. ¹

Artifact: “Incident Signals Catalog” mapped to systems (identity, endpoint, cloud, email, network, apps).

2) Inventory your detection inputs by category required by NIST

Build a table and assign owners.

Input category (required)	Examples	Owner	Where it lands
Security tool alerts	EDR, IDS/IPS, AV, email security	Security Ops	Ticket queue / SIEM
Logs	IAM, cloud audit logs, firewalls, app logs	Platform/SecOps	SIEM/log platform
Publicly available information	vendor advisories, vulnerability announcements relevant to your assets	SecEng/GRC	Intake queue
Internal/external reports	employee hotline, IT helpdesk, third-party notifications	IT/Privacy/TPRM	Intake queue

Control point: If an input exists but does not reach a monitored queue, treat it as a gap.

3) Centralize intake and triage (even if tooling is distributed)

You do not need a single tool, but you do need a single operating process:

• One intake queue (or integrated queues) where every signal can be tracked to closure.
• A triage rubric: severity, credibility, asset criticality, data sensitivity, and whether the signal meets your “indicator” definition.
• Clear escalation: when triage converts a signal into an “incident,” route it to incident handling procedures and on-call responders. ¹

Practical tip: Human reports and third-party notifications often bypass SOC workflows. Put them into the same triage path as automated alerts.

4) Establish monitoring review expectations and monitoring health checks

NIST requires “monitor,” which implies you can show it is actually being watched. Implement:

• Coverage checks: are key systems logging and are alerts enabled.
• Pipeline checks: are logs arriving; are parsers working; are alerts firing.
• Dead-letter checks: failed log deliveries, disabled sensors, expired API tokens. ¹

Evidence focus: Auditors often accept imperfect detection coverage if you can prove you track and remediate monitoring gaps.

5) Document triage decisions and retain supporting evidence

For each significant signal:

• What triggered it (tool alert, log, report, public intel).
• Who triaged and when.
• What data they reviewed (log excerpts, screenshots, event IDs).
• Decision (false positive, benign, needs investigation, declare incident).
• Escalation path and notifications initiated. ¹

6) Test the process with realistic scenarios

Pick scenarios that exercise each required channel:

• A tool alert scenario (EDR malware detection).
• A log-only scenario (suspicious IAM activity found via cloud audit logs).
• A public information scenario (new disclosure affecting your internet-facing component).
• A third-party report scenario (supplier reports compromise of a system that connects to you). ¹

Run tabletop or technical simulations and capture outcomes as evidence.

Required evidence and artifacts to retain

Keep artifacts that prove both design and operation:

Program design

• Monitoring and Detection Standard / Procedure that explicitly covers the four NIST input categories. ¹
• Incident Signals Catalog (precursors and indicators definitions).
• Logging and Alerting Source Inventory (systems, log types, owners, destinations).
• Triage rubric and severity matrix, including criteria for declaring an incident.

Operational evidence

• Samples of alerts and triage tickets showing investigation notes and closure codes.
• SIEM/search screenshots or exported query results supporting decisions.
• Monitoring health reports: missing logs, sensor status, alert pipeline failures and remediation actions.
• Records of internal/external reports intake (helpdesk tickets, email inbox workflow, hotline reports) linked to triage outcomes. ¹

Common exam/audit questions and hangups

Expect these questions, and prepare a one-page answer with linked evidence:

1. “Show me how you monitor for signs of an incident.” Bring the source inventory and a live walkthrough from signal to ticket. ¹
2. “How do you define precursors vs indicators?” Provide your Signals Catalog and examples of each. ¹
3. “What publicly available information do you monitor?” Show your intake workflow and how you decide relevance to your environment. ¹
4. “How do third-party reports get handled?” Demonstrate that external notifications enter the same triage process, not an orphaned mailbox. ¹
5. “How do you know monitoring is working?” Show monitoring health checks, known gaps, and remediation tracking.

Frequent implementation mistakes and how to avoid them

• Mistake: Treating tool deployment as compliance. Fix: require evidence of review, triage, and closure, not just tool screenshots. ¹
• Mistake: Logging without ownership. Fix: each log source needs an owner and a “failure mode” plan for when logs stop.
• Mistake: No path for human reports. Fix: route phishing reports, whistleblower-style tips, and customer complaints into the same incident signals queue. ¹
• Mistake: Ignoring public information unless a breach hits the news. Fix: define what public sources matter (vendor security advisories for your stack; credible exploitation reports) and document your intake decisions. ¹
• Mistake: Triage decisions not reproducible. Fix: standardize required fields in tickets (signal source, timestamp, assets, evidence reviewed, decision basis).

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so treat this as a “defensibility” requirement: if you cannot show monitoring of precursors and indicators across tools, logs, public information, and reports, you will struggle to defend incident response timeliness and completeness under related security, privacy, and contractual obligations. ¹

Practical execution plan (30/60/90)

Use a phased plan without calendar promises. The goal is fast operationalization, then hardening.

First 30 days (Immediate)

• Publish an “Incident Signals Catalog” with precursors and indicators definitions, plus examples relevant to your environment. ¹
• Build the detection input inventory across the four NIST categories, assign owners, and identify top gaps (missing logs, unmonitored inboxes, no public intel intake). ¹
• Stand up a single triage workflow (ticketing rules + minimum required fields).

Days 31–60 (Near-term)

• Connect high-value log sources to your log platform/SIEM and confirm alert routing into the triage queue. ¹
• Implement monitoring health checks and a simple exception process for known visibility gaps.
• Train IT/helpdesk, Privacy, and TPRM on how to submit and route internal/external reports as incident signals. ¹

Days 61–90 (Operational hardening)

• Run scenarios that test each input channel, then update playbooks and triage criteria based on what failed. ¹
• Start metrics you can defend qualitatively: volume by signal category, top recurring false positives, top log gaps, and time-to-triage trends (avoid publishing numbers unless you can support them).
• If you use Daydream for third-party risk workflows, connect third-party incident notifications and security advisories into the same evidence trail as your internal signals so you can show end-to-end intake, triage, and follow-up tasks without email archaeology.

Frequently Asked Questions

What counts as a “precursor” versus an “indicator”?

Precursors suggest an incident may occur (early warning signals). Indicators suggest an incident is occurring or occurred (evidence of compromise). Your process should define both in writing and use them consistently in triage. ¹

Do we need a SIEM to meet the signs of an incident requirement?

NIST requires monitoring via alerts, logs, public information, and reports, but it does not mandate a specific tool. You do need a consistent way to collect signals, review them, and retain evidence of triage outcomes. ¹

What “publicly available information” should we monitor?

Monitor sources that can credibly affect your environment, such as vendor advisories for products you run and credible vulnerability disclosures relevant to your internet-facing footprint. Document your intake criteria and decisions. ¹

How should third-party incident notifications be handled?

Treat third-party notifications as an external report input to your incident signal process. Route them into the same triage queue, record the evidence received, and track follow-up actions to closure. ¹

What evidence will an auditor expect to see?

Auditors typically want proof of (1) defined signals, (2) monitored inputs, (3) triage and escalation, and (4) operational records like tickets, log excerpts, and monitoring health checks. Keep examples across each required input category. ¹

How do we prevent the monitoring queue from becoming a false-positive graveyard?

Use a triage rubric, tune noisy rules with documented changes, and require closure codes and investigation notes. Track recurring false positives as a backlog item, not an ad hoc annoyance. ¹

Footnotes

1. Computer Security Incident Handling Guide