SC-26(1): Detection of Malicious Code

SC-26(1): Detection of Malicious Code requires you to implement technical and operational controls that detect malware in your environment, then prove those controls run consistently across endpoints, servers, and key traffic paths. To operationalize it quickly, define detection coverage targets, standardize tool configuration, centralize alerting, and retain evidence that detection is deployed, monitored, and acted on. ¹

Key takeaways:

• Define “malicious code detection” as an end-to-end capability: prevention plus detection plus response evidence.
• Standardize configurations and coverage across asset classes; exceptions need explicit approval and compensating controls.
• Your audit pass/fail hinges on evidence: deployment, configuration baselines, alert triage, and corrective actions.

The sc-26(1): detection of malicious code requirement is easy to describe and easy to fail in practice. Most programs have some mix of endpoint protection, email security, and network controls, but they cannot prove consistent deployment, consistent configuration, and consistent monitoring. Auditors then treat it as a control design gap (tools exist but are not governed) or an operating effectiveness gap (alerts exist but are not handled).

For a Compliance Officer, CCO, or GRC lead, the fastest path is to treat SC-26(1) as a “capability with receipts.” You need (1) defined coverage scope, (2) standardized detection controls by platform, (3) a documented operating procedure for alert handling, and (4) recurring evidence artifacts that demonstrate the control runs as described. This page gives you requirement-level implementation guidance you can hand to Security Operations and IT, then use to drive assessment-ready proof.

Where Daydream fits: use it to map SC-26(1) to a single control owner, a single implementation procedure, and a predictable evidence cadence so you are not rebuilding the story every audit cycle. ¹

Regulatory text

Control requirement: “NIST SP 800-53 control SC-26.1.” ¹

Operator interpretation of the text: SC-26(1) expects you to implement mechanisms that detect malicious code and to operate them as a managed control. In an assessment, this is typically evaluated as:

• Are detection mechanisms deployed across the defined scope (endpoints, servers, and other relevant components)?
• Are they configured to actually detect malicious code (not just installed)?
• Are alerts reviewed and acted on, with a repeatable process and retention of evidence?
  ²

Plain-English interpretation (what “good” looks like)

You meet SC-26(1) when you can show, on demand, that:

1. Your systems have malware detection controls in place (endpoint, server, and other relevant layers).
2. Those controls are configured using approved baselines (not ad hoc settings by team).
3. Detections generate alerts into an owned queue (SIEM/SOAR/ticketing).
4. Alerts are triaged within defined operational expectations and drive containment/remediation.
5. Exceptions are known, approved, time-bounded, and covered by compensating controls.

A common assessment failure mode is “tools everywhere, accountability nowhere.” Another is “coverage unknown,” where you cannot answer basic scoping questions like “Which servers are excluded from EDR and why?”

Who it applies to

SC-26(1) is relevant anywhere NIST SP 800-53 is used as the control baseline, including:

• Federal information systems
• Contractor systems handling federal data
  ¹

Operationally, it applies to environments where malicious code could enter or execute:

• Corporate endpoints (managed laptops/desktops)
• Servers (on-prem and cloud IaaS)
• Email and collaboration systems
• Web ingress/egress paths and proxy layers
• Software supply chain entry points (developer workstations, CI runners, artifact repos)

You do not need every possible tool. You do need defensible coverage and the ability to prove it.

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

Step 1: Assign a single accountable owner and define scope

• Name a control owner (often SecOps, Endpoint Engineering, or Cyber Defense).
• Define in-scope asset classes: endpoints, Windows/Linux servers, VDI, privileged admin workstations, and any high-risk enclaves.
• Define in-scope data flows where malware inspection is expected (email, web, file transfer paths), based on your architecture.

Deliverable: a one-page “SC-26(1) scope statement” tied to your asset inventory categories.

Step 2: Standardize your detection stack by layer

Create a simple coverage model auditors can understand:

Layer	Primary detection control	Minimum configuration expectations
Endpoint	EDR/next-gen AV	Real-time protection on, tamper protection on, automatic updates on, alert forwarding on
Server	EDR/server agent	Same as endpoint plus documented exclusions and performance constraints
Email	Email security gateway / cloud email protection	Attachment scanning, URL scanning, sandboxing (if used), quarantine policies
Web	Secure web gateway / proxy / DNS filtering	Malware blocking, reputation controls, logging to SIEM
File ingress	ICAP/file scanning where used	Scanning on download/upload paths, logging enabled

You can implement differently, but you must be able to explain your pattern and show it’s consistently applied.

Step 3: Create configuration baselines and exception handling

• Document “gold” configurations for each platform (Windows, macOS, Linux server, container hosts).
• Define allowable exclusions (e.g., specific directories, specific processes) and require:
  • business justification,
  • security approval,
  • time limit,
  • compensating controls.

This is where many organizations lose audits: they have exclusions but cannot show governance.

Step 4: Centralize telemetry and define alert triage procedures

• Ensure all malware detections feed to a central place (SIEM/SOAR and/or ticketing).
• Write a short SOP that covers:
  • alert severity mapping,
  • triage steps (validate, scope, contain),
  • escalation paths (IR lead, IT ops, app owners),
  • closure criteria (eradication + lessons learned note).

Operational expectation: an auditor will ask for a sample of detections and evidence they were handled consistently.

Step 5: Validate coverage continuously (not annually)

Build a recurring routine:

• Reconcile asset inventory vs. security agent inventory to identify unmanaged systems.
• Report drift: devices without agents, agents outdated, or reporting disabled.
• Test detections (tabletop + technical tests where allowed) to confirm signals reach the queue.

If you cannot quantify coverage reliably, document the method you use to detect gaps and the workflow to remediate them.

Step 6: Package evidence into an assessor-ready binder

Make evidence predictable and periodic. In Daydream terms, map SC-26(1) to:

• a control owner,
• an implementation procedure,
• recurring evidence artifacts (monthly/quarterly), so the evidence exists before the assessor asks. ¹

Required evidence and artifacts to retain

Retain artifacts that prove both design and operation:

Design / configuration

• Architecture diagram or written description of malware detection points (endpoint, server, email, web).
• Tool configuration baselines (screenshots or exported policies).
• Exception register for AV/EDR exclusions with approvals.
• Data flow/logging diagram showing detections routed to SIEM/ticketing.

Operational / effectiveness

• Agent deployment reports (by OU/account/subscription, by platform).
• Health dashboards: devices not reporting, signature/update status, policy compliance.
• Sample alerts with linked tickets showing triage, containment, remediation, and closure notes.
• Change records for detection policy updates and emergency pushes.
• Metrics you already track (qualitative is fine): backlog status, aging review notes, tuning actions.

Retention tip: keep at least one full audit period of evidence in a single folder structure with consistent naming (by month and artifact type). Avoid scatter across chat threads.

Common exam/audit questions and hangups

Expect these questions, and prepare answers plus artifacts:

1. “Show me coverage.”
   They will ask how you know endpoints/servers are protected and reporting.

2. “Show me configuration.”
   They will ask for the actual policy objects and who can change them.

3. “Show me operations.”
   They will sample detections and trace them through ticket closure.

4. “What about exceptions?”
   They will inspect exclusions for governance and whether exceptions are reviewed.

5. “What about cloud and ephemeral assets?”
   They will ask how you handle short-lived instances and whether detection is baked into images or provisioning workflows.

Hangup to avoid: presenting a policy statement without logs, reports, and real tickets.

Frequent implementation mistakes (and how to avoid them)

• Mistake: “Installed” equals “effective.” Agents installed but not reporting, outdated, or misconfigured still fail.
  Fix: track agent health and policy compliance, and keep health reports as evidence.

• Mistake: Uncontrolled exclusions. Performance-driven exclusions proliferate and become permanent.
  Fix: require approvals, time-bounds, and periodic review; store an exclusions register.

• Mistake: Alert floods with no triage discipline. Teams mute noisy rules and miss true positives.
  Fix: document tuning decisions, severity mapping, and escalation rules; keep sample cases.

• Mistake: Blind spots in “non-standard” environments. Build servers, OT, lab networks, VDI pools, and contractor devices slip out of scope informally.
  Fix: explicitly classify them as in-scope or out-of-scope, and document compensating controls for exclusions.

Enforcement context and risk implications

No public enforcement cases were provided in the supplied source catalog for SC-26(1). ¹

Risk-wise, weak malicious code detection shows up as:

• increased dwell time before discovery,
• broader blast radius (lateral movement),
• higher likelihood of data exposure,
• inability to support incident reporting with reliable timelines and scope.

For a federal contractor, control failures can also become contractual and assessment findings, which then drive corrective action plans and ongoing monitoring scrutiny under your applicable program baseline. ³

A practical 30/60/90-day execution plan

First 30 days (stabilize and define)

• Assign SC-26(1) control owner and confirm scope boundaries aligned to asset inventory categories.
• Inventory current detection controls by layer (endpoint/server/email/web) and document gaps.
• Stand up an evidence folder and start collecting baseline artifacts: policy exports, screenshots, alert routing proof.

Days 31–60 (standardize and operationalize)

• Publish configuration baselines and lock down who can change them (RBAC + change control).
• Implement an exclusions governance workflow with approvals and review checkpoints.
• Ensure alerts route to a central queue and write the triage SOP with escalation paths.

Days 61–90 (prove operating effectiveness)

• Run coverage reconciliation (asset inventory vs agent inventory) and remediate drift.
• Perform a controlled detection validation exercise and capture evidence that alerts/tickets flow end-to-end.
• Build an assessor-ready packet: coverage reports, sample alerts with tickets, exclusions register, and SOPs.

If you manage SC-26(1) in Daydream, keep the owner, procedure, and evidence checklist bound to the requirement so operations teams cannot “complete” the control without leaving audit-ready artifacts. ¹

Frequently Asked Questions

Does SC-26(1) require EDR specifically?

NIST SP 800-53 does not prescribe a single product in the provided excerpt, but assessors will expect a defensible malicious code detection capability across your in-scope systems. Pick controls that match your architecture and prove consistent deployment and monitoring. ³

What systems are usually in-scope for malicious code detection?

Endpoints and servers are the baseline expectation in most environments, then high-risk ingress paths like email and web. Define scope explicitly and tie it to asset inventory categories so you can prove coverage. ¹

How do we handle systems that cannot run an EDR agent?

Document the exception, security approval, and compensating controls (for example, network segmentation, restricted admin paths, increased monitoring at choke points). Keep the exception time-bounded and review it on a recurring basis.

What evidence is strongest for audits?

Auditors tend to accept three things quickly: agent/coverage reports, exported configuration policies, and a small sample of alerts tied to incident or ticket records that show triage and remediation. Keep those artifacts on a recurring cadence. ³

How do we prove detection is working without running “malware tests”?

Use operational evidence you already have: historical detections, quarantines, blocked attachments/URLs, and the corresponding tickets and response notes. If you run validation tests, capture proof that the alert made it into the central queue and was handled under the SOP.

Who should own SC-26(1) in a typical organization?

Security Operations commonly owns detection and alert handling, with Endpoint/IT Engineering owning agent deployment and configuration enforcement. GRC should own requirement mapping, evidence standards, and assessment readiness packaging. 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

3. NIST SP 800-53 Rev. 5