SC-5(3): Detection and Monitoring

SC-5(3): Detection and Monitoring requires you to deploy and operate monitoring tools that detect indicators of denial-of-service (DoS) attacks targeting your system and DoS activity originating from your system. Operationalize it by defining “DoS indicators,” instrumenting network/app telemetry, setting actionable alert thresholds, and retaining proof that monitoring runs continuously and is reviewed. ¹

Key takeaways:

• You must monitor for DoS both inbound (against you) and outbound (launched from you). ¹
• Auditors will look for always-on detection, tuned alerting, and documented response paths, not just a tool purchase. ¹
• Evidence quality matters: configs, alert rules, dashboards, tickets, and review records should tie back to SC-5(3). ¹

A DoS event is rarely subtle. What fails most programs is not “we had no security tools,” but “we couldn’t show that our tools were configured to detect DoS indicators, monitored the right places, and produced actionable alerts that humans actually handled.” SC-5(3): Detection and Monitoring is a requirement-level control enhancement under NIST SP 800-53 that forces you to make DoS monitoring explicit and provable. ²

For a Compliance Officer, CCO, or GRC lead, the fastest path is to treat SC-5(3) as an operational capability with three parts: (1) defined indicators (what you are detecting), (2) deployed monitoring tools and alert logic (how you detect), and (3) repeatable oversight with retained artifacts (how you prove it works). This page translates the requirement into concrete steps, assigns accountable owners, and lists the artifacts that typically satisfy assessors during system security plan (SSP) reviews and control testing. ¹

Regulatory text

Excerpt: “Employ the following monitoring tools to detect indicators of denial-of-service attacks against, or launched from, the system: {{ insert: param, sc-05.03_odp.01 }} ; and” ¹

Operator interpretation of the excerpt

• You are required to employ monitoring tools (not informal checks) that can detect indicators of DoS attacks. ¹
• Monitoring must cover two directions:
  1. Attacks against the system (inbound targeting availability).
  2. Attacks launched from the system (outbound abuse, bot activity, reflection/amplification participation). ¹
• The “{{ insert: param }}” placeholder means the catalog allows organization-defined specifics for the toolset. Your job is to define the tool categories and coverage and then prove they are in place and operating. ¹

Plain-English requirement (what SC-5(3) demands)

You need continuous monitoring that can spot DoS conditions early enough to trigger response. Practically, that means:

• Instrumenting network edge, application entry points, and critical dependencies to detect volume spikes, protocol anomalies, connection exhaustion, and service saturation symptoms.
• Correlating telemetry so you can tell the difference between legitimate traffic growth and a DoS pattern.
• Ensuring alerts are routed to people or on-call rotations with a defined runbook and ticket trail. ¹

Who it applies to (entity + operational context)

SC-5(3) commonly applies where you are expected to align with NIST SP 800-53 controls, including:

• Federal information systems.
• Contractor systems handling federal data, including cloud-hosted and hybrid environments that provide services to federal agencies or store/process federal information. ¹

Operationally, it applies most strongly to:

• Internet-facing services (web apps, APIs, identity endpoints).
• Central shared services (DNS, VPN, email gateways, remote access).
• Multi-tenant or shared infrastructure where a single tenant’s issue can cascade into availability loss.

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

Step 1: Define DoS “indicators” for your environment

Create a short, approved definition of what you treat as DoS indicators. Make it operational, not academic. Examples to include in your definition set:

• Traffic volume anomalies at ingress/egress.
• Connection state exhaustion (SYN backlog, concurrent sessions, NAT table pressure).
• Application-layer saturation (high request rates to expensive endpoints, repeated auth attempts that spike CPU).
• Error-rate and latency signals tied to availability impact (timeouts, 5xx spikes).
• Outbound anomalies that suggest your systems are participating in attacks (unexpected egress bursts, unusual destinations/ports).

Deliverable: “SC-5(3) DoS Indicators Register” mapped to key services and telemetry sources. ¹

Step 2: Inventory monitoring points and tools (coverage map)

Build a coverage map that answers: “Where would we see DoS first?” Include:

• Network edge (CDN/WAF, DDoS protection service, load balancers).
• Firewall/IDS/IPS or cloud network telemetry.
• Application and API gateway metrics.
• DNS and identity provider telemetry (if in scope).
• Host/container platform signals for resource starvation.

Deliverable: “DoS Monitoring Coverage Map” showing signal source → tool → alert destination → owner. ¹

Step 3: Implement alert logic that is actionable

Tools are not controls unless they alert usefully. Configure detections in a way that a responder can act on:

• Create alert rules for your indicator set.
• Add context: affected service, baseline traffic, top talkers, geo distribution, endpoint, mitigation suggestions.
• Define severity and routing (SOC queue, on-call, pager, email distribution list).
• Reduce noise with suppression rules for known events (planned load tests, marketing launches), but document exceptions.

Deliverable: Alert rule catalog or exported detection-as-code with change history. ¹

Step 4: Establish monitoring operations (who checks what, and when)

Define an operating rhythm:

• Who owns detection engineering vs operations triage.
• How alerts become incidents (ticketing workflow, escalation).
• How you validate sensors are alive (heartbeat alerts, “no logs received” alarms).
• How you review missed detections (post-incident improvement).

Deliverable: “DoS Monitoring SOP” plus on-call and escalation matrix. ¹

Step 5: Test that monitoring detects both inbound and outbound DoS indicators

You need proof that your monitoring would catch:

• Inbound DoS symptoms (service degradation, edge saturation).
• Outbound attack indicators (unexpected egress patterns).

Practical test methods:

• Tabletop: walk through a simulated DoS scenario and verify alert routing and decision points.
• Controlled test in a non-production environment: generate high request rates or connection churn and validate alerts.
• Validation via historical events: show prior alerts and handling, if available.

Deliverable: Test plan + test results + remediation tickets for gaps found. ¹

Step 6: Document the control in your SSP and map recurring evidence

Document:

• Monitoring tool stack and scope.
• Which DoS indicators are covered.
• Alert thresholds (high level) and routing.
• Roles and responsibilities.
• Evidence produced and retained.

If you use Daydream, this is where it fits naturally: map SC-5(3) to a control owner, attach the SOP, and schedule recurring evidence pulls (alert exports, dashboard snapshots, review sign-offs) so you can answer assessor requests without rebuilding history. ¹

Required evidence and artifacts to retain

Keep artifacts that prove design, implementation, and operation:

Design evidence

• DoS Indicators Register (approved, dated).
• DoS Monitoring Coverage Map (service-by-service).
• Architecture diagrams showing telemetry flow (edge → SIEM/SOAR → ticketing).

Implementation evidence

• Tool configuration exports (WAF/DDoS profiles, SIEM rules, IDS signatures where relevant).
• Alert routing configuration (paging policies, distribution lists).
• “Sensor health” configuration (log pipeline monitoring, agent status, cloud integration status).

Operational evidence

• Alert samples (sanitized) showing DoS indicator detection and triage.
• Incident/ticket records with timestamps, assignments, and closure notes.
• Monitoring review records (weekly/monthly review notes, tuning changes, false-positive rationale).
• Test reports and corrective actions.

Retention tip: retain enough to show continuity across the assessment period and that changes are controlled (change tickets or version history). ¹

Common exam/audit questions and hangups

Assessors and auditors commonly probe these areas:

• “Show me how you detect DoS launched from your system.” Many teams only cover inbound. Be ready with egress detections and network flow monitoring.
• “Which tools are in scope and which systems are covered?” Answer with your coverage map, not a list of products.
• “How do you know the monitoring is operating?” Provide sensor health alerts, log ingestion dashboards, and review records.
• “What happens when an alert fires?” Provide runbooks, escalation paths, and actual tickets tied to alerts.
• “How do you tune thresholds?” Show change records and rationale, not ad hoc edits. ¹

Frequent implementation mistakes (and how to avoid them)

1. Buying DDoS protection but not proving monitoring.
   Fix: export configurations, keep dashboards, and retain alert/ticket history. ¹

2. Only monitoring the perimeter.
   Fix: include application-layer and dependency indicators (API gateway, auth endpoints, DNS). ¹

3. No outbound detection.
   Fix: implement egress monitoring for spikes, unusual destinations, and anomalous protocols; document how you investigate outbound DoS indicators. ¹

4. Alert fatigue and ignored notifications.
   Fix: define severity, route to a staffed queue, review noise regularly, and keep tuning records. ¹

5. No control owner.
   Fix: assign one accountable owner for SC-5(3) with named backups; track evidence production on a calendar in your GRC system. ¹

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so you should treat this as a framework conformance and assurance risk rather than a cited enforcement trend in this write-up. ¹

Risk implications you can articulate internally:

• DoS can create availability failures, missed mission objectives, SLA violations, and incident reporting obligations depending on your contract and environment.
• Lack of monitoring evidence increases the chance of an assessment finding even when tools exist, because SC-5(3) is explicitly about employing monitoring tools and detecting indicators. ¹

A practical 30/60/90-day execution plan

First 30 days (stabilize scope and evidence)

• Assign a SC-5(3) control owner and backups; document RACI for SecOps, NetOps, and AppOps.
• Publish the DoS Indicators Register and DoS Monitoring Coverage Map for your highest-criticality services.
• Identify evidence sources and start an evidence log (what you will export, where it is stored, who approves). ¹

By 60 days (make detections real and testable)

• Implement or refine alert rules for each indicator class; confirm routing to a monitored queue.
• Add sensor health monitoring for log pipelines and agents so “silent failure” becomes detectable.
• Run at least one tabletop test and capture artifacts (agenda, outputs, action items). ¹

By 90 days (operationalize and make it assessor-ready)

• Complete a detection tuning cycle (reduce top recurring false positives, close coverage gaps).
• Demonstrate inbound and outbound coverage with test results or historical ticket examples.
• Finalize SSP language for SC-5(3) and implement recurring evidence collection in Daydream (or your existing GRC workflow) tied to control objectives and review cadences. ¹

Frequently Asked Questions

What counts as a “monitoring tool” for SC-5(3)?

Any system that collects telemetry and produces actionable detection of DoS indicators can qualify, including SIEM detections, WAF/CDN alerting, network flow analytics, or cloud-native monitoring. Your evidence must show it detects DoS indicators against or launched from the system. ¹

Do we need a dedicated DDoS scrubbing service to meet SC-5(3)?

SC-5(3) is written as a monitoring requirement, not a mandate for a specific mitigation service. If you do have a scrubbing service, treat its alerting and reporting as part of your monitoring evidence. ¹

How do we prove “launched from the system” detection?

Keep egress telemetry (flow logs, firewall logs, proxy logs) and alert rules that detect abnormal outbound patterns, plus tickets showing investigation. Assessors want to see you can spot your assets participating in DoS activity, not only being targeted. ¹

What evidence is strongest for auditors: screenshots or exports?

Exports with timestamps and change history are usually stronger because they show configuration and operation over time. Supplement with screenshots for dashboards if the platform cannot export easily, and store them with an evidence index tied to SC-5(3). ¹

We’re cloud-first. Is cloud-native monitoring enough?

It can be, if you can show coverage for edge, network, and application indicators, and that alerts route to responders with a ticket trail. Gaps often appear at the internet edge (WAF/CDN) and at egress monitoring across accounts/subscriptions. ¹

How should a GRC team track SC-5(3) without drowning in SOC data?

Track control ownership, the coverage map, the alert rule inventory, and a small set of recurring evidence pulls (rule exports, sample alerts, review notes). Daydream works well here because it ties the procedure and recurring artifacts directly to the SC-5(3) requirement and preserves assessment-ready history. ¹

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON

2. NIST SP 800-53 Rev. 5; Source: NIST SP 800-53 Rev. 5 OSCAL JSON