AT-2(4): Suspicious Communications and Anomalous System Behavior

AT-2(4) requires you to run security awareness “literacy” training that teaches personnel to recognize suspicious communications (like phishing and social engineering) and anomalous system behavior (like unexpected login prompts or odd device activity), using your organization-defined training topics. Operationalize it by defining the required topics, assigning ownership, delivering role-appropriate training on a repeatable cadence, and retaining completion and content evidence.

Key takeaways:

• Define the exact training topics and examples your environment faces, then teach to those topics.
• Make the training operational: role mapping, delivery, tracking, and escalation paths for reporting suspicious activity.
• Evidence wins audits: retain training content, attendee rosters, completion status, and updates tied to real incidents and threat changes.

The at-2(4): suspicious communications and anomalous system behavior requirement is easy to describe and easy to fail in an assessment. Assessors rarely accept “we do annual security awareness” as sufficient unless you can prove the training explicitly covers (1) suspicious communications and (2) anomalous behavior in your systems, and that it is delivered to the right people in a consistent, tracked way.

This enhancement sits under AT-2 (Awareness Training) in NIST SP 800-53 Rev. 5. In practice, it becomes a coordination control across Compliance/GRC, Security Awareness, SOC/IR, IT, and HR/L&D. You need clear “what to teach,” a repeatable “how we teach it,” and a closed-loop “how we measure and improve it.” The training must match your environment: cloud identity prompts, MFA push fatigue, collaboration-tool impersonation, helpdesk social engineering, endpoint pop-ups, and unexpected system behavior that staff might otherwise ignore.

The goal is not to turn employees into analysts. The goal is to teach recognition, quick triage, and correct reporting so suspicious communications and odd system behavior reach the right responders fast, with fewer false assumptions and fewer delayed escalations.

Regulatory text

Requirement (verbatim): “Provide literacy training on recognizing suspicious communications and anomalous behavior in organizational systems using {{ insert: param, at-02.04_odp }}.” ¹

Operator interpretation: You must (1) define the organization-determined parameters (the training topics and scope referenced by the control), (2) deliver training that builds practical recognition skills for suspicious communications and anomalous system behavior, and (3) prove it happened through durable evidence. NIST frames this as “literacy training,” which implies practical understanding and action, not a policy read-through. ²

What “organization-defined parameters” means in practice

AT-2(4) includes a placeholder for your org’s defined inputs. Treat that as a required configuration item:

• Training topics you commit to cover (your minimum required curriculum)
• Audience scope (who must take it; role-based if needed)
• Delivery method (LMS, live sessions, security awareness platform, onboarding module)
• Refresh triggers (e.g., new threats, incident learnings, major tooling changes)

Document these in a short control procedure so the requirement is auditable and repeatable.

Plain-English interpretation of the requirement

You must teach your workforce how to spot and respond to two things:

1. Suspicious communications: messages intended to trick someone into revealing credentials, approving access, sending money/data, installing software, or bypassing controls. This includes email, SMS, voice, collaboration tools, ticketing systems, and vendor/customer impersonation.
2. Anomalous system behavior: system activity that looks “off” for normal operations and may indicate compromise, misconfiguration, or malicious activity. Examples include repeated MFA prompts, unexpected password reset flows, unusual pop-ups, sudden slowness coupled with new processes, disabled security tools, or logins from unusual locations (as visible to the user).

Your training must be practical: what it looks like in your environment, what to do immediately, and how to report it so Security can act.

Who it applies to

Entity types

• Federal information systems and programs adopting NIST SP 800-53 Rev. 5 controls. ²
• Contractor systems handling federal data where NIST SP 800-53 is flowed down contractually or used to satisfy system security plan control baselines. ²

Operational context (who inside the organization)

AT-2(4) usually applies to:

• All workforce members with corporate email or collaboration accounts
• Anyone with access to organizational systems (employees, contractors, temps, interns)
• Elevated-risk roles: IT admins, helpdesk, finance/AP, HR, engineering, executive assistants, SOC, and customer support

If you scope out certain populations, you need a defensible rationale (for example, no system access) and a way to prove that scoping decision.

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

Step 1: Assign ownership and define the control boundary

• Control owner: typically GRC (accountable) with Security Awareness/IT (responsible).
• Systems in scope: define which environments the training is meant to protect (corporate IT, cloud identity, key SaaS, endpoints). Keep it short and specific.

Deliverable: AT-2(4) control implementation procedure (1–2 pages) mapped to an owner, cadence, and evidence outputs. ¹

Step 2: Define your required curriculum (the org-defined parameters)

Build a curriculum checklist that includes, at minimum:

• Suspicious communications recognition (phishing, smishing, vishing, QR-based lures, internal impersonation)
• Common pretexts relevant to your business (invoice fraud, payroll change, password reset, vendor onboarding)
• “Trust signals” that are unreliable (display name spoofing, urgent tone, familiar logos)
• Anomalous behavior examples specific to your environment (MFA fatigue prompts, unusual OAuth consent screens, endpoint security disabled alerts, unexpected remote access prompts)
• Expected reporting channels and what details to include
• “Do not do” actions (do not forward suspicious links externally; do not approve unexpected MFA prompts)

Tip: Tie anomalous behavior examples to actual tools your users see (SSO provider prompts, endpoint agent notifications, collaboration platform security banners). Generic training is where programs stall.

Step 3: Make reporting paths operational (not theoretical)

Training has to connect to real intake:

• Define a single primary reporting route (e.g., “Report Phish” button, security inbox, service desk category).
• Define a backup route for edge cases (no access to email, mobile-only).
• Define triage ownership (SOC, IT, service desk with escalation).
• Publish “what happens after you report” in one paragraph to build trust and reduce repeat pings.

Deliverable: A short reporting SOP and the user-facing “how to report” job aid.

Step 4: Deliver role-appropriate training and track completion

Operational requirements you should implement:

• Include AT-2(4) content in onboarding for any role with system access.
• Provide periodic refresh training on suspicious communications and anomalous behavior.
• Provide targeted modules for high-risk roles (finance, helpdesk, admins).

Tracking expectations:

• Completion status by person/role
• Exceptions process (LOA, contractors without LMS access) with documented make-up training

Step 5: Validate effectiveness and update content based on real signals

AT-2(4) is stronger when you show a feedback loop:

• Use common failure modes from internal tickets (phish reports, MFA push complaints, helpdesk social engineering attempts) to update training examples.
• Add “new pattern” micro-lessons when tooling changes (new MFA method, new ticketing portal, new collaboration platform features).

You do not need to claim statistical improvement. You do need to show you adapt content to observed risk.

Step 6: Map the requirement to recurring evidence artifacts (assessment-ready)

Create an evidence matrix that lists:

• Artifact name
• System of record (LMS, awareness platform, HRIS)
• Frequency of generation
• Owner and backup
• Retention location

Daydream is useful here because it can keep the control mapped to an owner, a written procedure, and a predictable evidence set so collection does not become a quarterly scramble.

Required evidence and artifacts to retain

Retain evidence that proves design (what you planned) and operation (what happened):

• Training content: slides, module screenshots, scripts, or vendor course outline showing suspicious communications + anomalous behavior coverage
• Org-defined parameters: the documented topic list and audience scope referenced by the control
• Completion reports: exported LMS/awareness platform reports showing assignments and completions
• Roster logic: how you determined who is in scope (HRIS extract, IAM group mapping)
• Exceptions log: waivers, alternate training, new hires pending completion, contractors
• Communications: training announcements, reminders, onboarding checklist inclusion
• Update history: change log or versioning tied to new threats or internal incidents

Common exam/audit questions and hangups

Assessors commonly ask:

• “Show me where your training explicitly covers anomalous system behavior, not just phishing.”
• “Who is required to take it, and how do you prove the population is complete?”
• “How do contractors get trained, and where is that tracked?”
• “How quickly do new hires receive training, and what happens if they miss it?” (Answer qualitatively if you can’t support a numeric SLA.)
• “What is the user reporting path, and is it tested in practice?”

Hangups that delay audits:

• Training exists but content cannot be produced (only a vendor invoice, no outline).
• Completion data is partial or not tied to HR/IAM population.
• “Anomalous behavior” is interpreted as a SOC-only topic; end users never receive those examples.

Frequent implementation mistakes and how to avoid them

Mistake	Why it fails	Fix
Treating AT-2(4) as “annual security training”	The enhancement expects literacy on two specific themes	Add explicit modules/sections and keep the content as evidence 1
No organization-defined parameters	Placeholder text implies you must define inputs	Document curriculum topics, audience, and triggers in a control procedure
Training teaches recognition but not reporting	Users spot issues but don’t escalate correctly	Add a one-page job aid and embed reporting steps in the module
No role differentiation	High-risk roles face different attack patterns	Assign targeted modules to finance/helpdesk/admins
Evidence is scattered	Audits stall on retrieval	Create an evidence register and store exports centrally

Enforcement context and risk implications

No public enforcement cases were provided in the source material for this requirement. Operationally, gaps in AT-2(4) increase the chance that phishing, impersonation, and early compromise indicators go unreported or are reported too late. That raises incident impact, investigation time, and the likelihood that technical controls fail silently because users ignore warning signs.

Practical 30/60/90-day execution plan

Use phases (not time-bound promises) that match your delivery reality.

First 30 days (Immediate stabilization)

• Assign a control owner and backup.
• Draft the AT-2(4) procedure with your organization-defined parameters (topics, audience, delivery, evidence).
• Inventory current training content; mark where suspicious communications and anomalous behavior are covered and where they are missing.
• Confirm the reporting channel(s) and write the user-facing job aid.

Next 60 days (Program build-out)

• Update training modules to include environment-specific anomalous behavior examples (SSO, MFA, endpoint prompts).
• Implement role-based assignments for high-risk groups.
• Connect HR/IAM population lists to training assignment logic.
• Run an evidence dry-run: export completion reports and store them in your audit repository.

By 90 days (Operational maturity)

• Add a content update workflow tied to incident learnings and new threat patterns.
• Test the reporting path (tabletop or operational check) and confirm triage ownership.
• Establish recurring evidence capture (scheduled exports, versioned content snapshots).
• If you use Daydream, map AT-2(4) to the owner, procedure, and recurring evidence artifacts so collection stays continuous rather than audit-driven.

Frequently Asked Questions

Does AT-2(4) require phishing simulations?

The text requires literacy training on recognizing suspicious communications and anomalous behavior, not a specific exercise type. Simulations can support effectiveness, but you still need explicit training content and completion evidence. ¹

What counts as “anomalous system behavior” for end-user training?

Focus on what users can observe: unusual MFA prompts, unexpected login redirects, surprise permission consent screens, security tool disabled messages, or device behavior that deviates from normal. Keep examples tied to your actual stack so users recognize them.

Can we meet this with a third-party security awareness platform course?

Yes, if you can produce the course outline or screenshots showing coverage of both suspicious communications and anomalous behavior, and you can export completion records for your in-scope population. Keep vendor content versions because libraries change over time.

Who must take the training—only employees?

Scope should cover anyone with access to organizational systems, including contractors, if they can receive or act on suspicious communications or observe anomalous behavior. If a group is excluded, document the rationale and access limitations.

What evidence do auditors usually want first?

They typically ask for (1) the training content, (2) the completion report, and (3) the population list showing who was required to take it. Have those three artifacts packaged together to reduce back-and-forth.

How do we operationalize “organization-defined parameters” without over-documenting?

Put the parameters in a short control procedure: required topics, audience groups, delivery channels, and evidence outputs. Keep it to what you can execute and prove, then revise it when your environment changes. ¹

Footnotes

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

2. NIST SP 800-53 Rev. 5