SI-3(4): Updates Only by Privileged Users

SI-3(4) is a narrow control enhancement with a practical goal: stop untrusted actors, standard users, and uncontrolled automation from changing the thing you depend on to detect malware. Updates to malicious code protection mechanisms are powerful. They can improve detection, but they can also be used to disable protections, introduce malicious “updates,” or create blind spots by downgrading engines or changing signature sources.

Operationalizing SI-3(4) is mostly about governance translated into technical guardrails. You need two decisions in writing: who counts as “privileged” for this purpose, and what “directed by” means in your environment (manual approval, scheduled updates approved by security, or centralized orchestration). Then you enforce it with endpoint security configuration, identity controls, and change management so updates are controlled, logged, and reviewable.

This page is written for a Compliance Officer, CCO, or GRC lead who needs to drive implementation with security and IT operations quickly, while staying assessment-ready for NIST SP 800-53 Rev. 5-aligned programs. ¹

Regulatory text

Requirement (verbatim): “Update malicious code protection mechanisms only when directed by a privileged user.” ²

What an operator must do:

• Ensure updates to malware protection components (signature definitions, engines, agents, reputation feeds, configuration that controls update sources) occur only under the control of a privileged role.
• Prohibit standard users and unapproved processes from initiating, altering, or redirecting those updates.
• Make the authorization path and the resulting update events auditable so an assessor can confirm the control operates consistently. ²

Plain-English interpretation

SI-3(4) expects you to treat malware protection updates as a privileged change. A normal user should not be able to:

• change where updates come from,
• force a downgrade,
• disable or “pause” protection by manipulating update state,
• install a different security agent,
• swap signature feeds or tamper with local definition files.

“Directed by a privileged user” can be satisfied in practice by:

• a privileged administrator initiating updates in a central console,
• security-approved automatic updates that are configured and locked down by privileged administrators,
• a change-controlled process where update policy changes require privileged approval and are deployed through managed tooling.

What won’t satisfy an assessor: “endpoints update themselves whenever they want and users can click ‘update now’ or change the update server,” even if that usually works.

Who it applies to

Entities: Federal information systems and contractor systems handling federal data commonly inherit this expectation when aligning to NIST SP 800-53 Rev. 5. ¹

Operational scope (what to include in your inventory):

• Endpoints (corporate laptops/desktops, VDI images)
• Servers (Windows/Linux, on-prem and IaaS)
• Cloud workloads (VMs, containers where an agent runs, managed services where applicable)
• Email and web security controls that use malware engines/feeds
• Any centralized management plane used to push updates (EDR/AV console, MDM, configuration management)
• Third-party-managed security tooling where the third party performs update actions on your behalf (you still need direction, authorization, and evidence)

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

1) Define the privileged direction model (policy + RACI)

Create a short control procedure that answers:

• Privileged roles: Which roles may direct updates (e.g., Security Operations admin, Endpoint Security admin). Tie to your IAM role catalog.
• Direction method: Central console push, scheduled updates, or change-ticket-approved updates.
• Change boundary: What counts as an “update” vs. a “configuration change” (treat both as privileged for simplicity).
• Emergency handling: Who can approve out-of-band updates and how it is documented.

Deliverable: a one-page “SI-3(4) operating procedure” with an owner, reviewers, and enforcement points.

2) Enforce least privilege for the security management plane

Lock down the consoles and APIs that can:

• approve/push definition updates,
• change update sources,
• modify tamper protection,
• uninstall/disable agents,
• change policy that affects update behavior.

Minimum expectations:

• RBAC with named admin roles (no shared accounts).
• MFA on admin access.
• Admin actions logged and retained.

If you have PAM, put console admin roles behind it. If you do not, at least require separate admin accounts and conditional access policies.

3) Remove end-user control over updates on endpoints and servers

On managed assets:

• Disable local UI controls that allow users to change update settings.
• Enable agent tamper protection (prevents stopping services, editing local definition stores, or uninstalling without approval).
• Restrict local admin rights broadly; where local admin is needed, use just-in-time elevation and logging.

On unmanaged or BYOD endpoints that access sensitive systems, you need compensating controls (for example, access restrictions, VDI, or requiring managed device posture) because SI-3(4) is hard to guarantee without management.

4) Control the update channel and validate the source

From an assessor’s perspective, “directed by a privileged user” also implies you know what you are directing:

• Standardize update sources (vendor cloud, internal mirror, approved repository).
• Block endpoints from pulling updates from arbitrary sources.
• If you run an internal update mirror, control administrative access and log changes.

This is where teams get surprised: if proxy rules allow direct access to random update hosts, a compromised device can be coerced into unsafe behavior.

5) Put update policy changes through change control

Define which changes require a ticket/approval:

• changing update cadence or rings,
• switching update sources,
• pausing updates,
• exclusions that affect detection,
• agent version upgrades/downgrades.

Your goal is a clear audit trail that a privileged user directed the change. That can be a change record, an approved pull request (for infrastructure-as-code), or a console audit log correlated to an approver.

6) Monitor and alert on “non-directed” signals

You need detective coverage for:

• endpoints that stop updating,
• agents that are missing or unhealthy,
• tamper protection disabled,
• local configuration drift,
• update source changes.

Route events to your SIEM or security monitoring workflow and assign ownership for triage.

7) Validate with a control test you can repeat

Run a simple test on a representative sample:

• attempt to change update settings as a standard user,
• attempt to stop/uninstall agent without privileged approval,
• confirm only privileged roles can initiate/push updates,
• confirm logs show who did what and when.

Write the test steps and keep the output as evidence.

Required evidence and artifacts to retain

Assessors typically want proof of design and operating effectiveness. Keep:

• SI-3(4) procedure: role definition, direction method, scope, exceptions. ²
• RBAC/PAM evidence: role assignments for the security console; MFA/conditional access screenshots or exports.
• Configuration baselines: MDM/Group Policy/endpoint security policy showing users cannot modify update settings; tamper protection enabled.
• Audit logs: console logs showing update policy changes and update actions tied to privileged identities.
• Change records: tickets/approvals for update source changes, engine upgrades, or paused updates.
• Monitoring evidence: reports/dashboards for update compliance and agent health; alerts for drift.
• Exception register: systems that cannot comply, compensating controls, time-bound remediation plan.

Tip for operators: store these in a single control evidence folder with a recurring capture cadence. Daydream is useful here as the system of record to map SI-3(4) to the control owner, the procedure, and the recurring evidence artifacts so evidence collection stays consistent across audit cycles. ²

Common exam/audit questions and hangups

1. “Define privileged user.” Is it IT admin, security admin, or both? Show role definitions and assignments.
2. “What does ‘directed by’ mean here?” Show whether updates are centrally orchestrated, scheduled under privileged configuration, or approved via change control.
3. “Can a standard user click ‘update now’?” If yes, you will likely need to justify why that still constitutes privileged direction (hard to defend) or change the configuration.
4. “How do you prevent tampering or uninstall?” Show tamper protection, removal protections, and admin access controls.
5. “Show me evidence for the last change.” Be ready to produce the most recent update policy change record and the matching console audit event.

Frequent implementation mistakes and how to avoid them

Mistake	Why it fails SI-3(4)	How to avoid
Treating auto-updates as “nobody directed it”	Assessors may read “directed” as an explicit privileged decision	Document that privileged admins configured and locked the auto-update policy; keep audit logs of that configuration 2
Allowing local admin sprawl	Local admins can often change security agents and update settings	Reduce local admin, use JIT elevation, enable tamper protection
No evidence of who changed update settings	Control may exist but can’t be proven	Centralize logging; retain console audit logs and change approvals
Update source is changeable on the endpoint	Malware can redirect feeds or block updates	Enforce update sources centrally; block unauthorized endpoints changes
Exceptions with no expiration	Drift becomes normal	Maintain an exception register with an owner and closure criteria

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this specific requirement, so this page does not cite enforcement outcomes.

Risk-wise, SI-3(4) reduces the chance that a compromised endpoint or malicious insider can neutralize malware defenses by manipulating updates. If an incident occurs, your ability to show “updates were privileged-directed and logged” also supports incident scoping and root cause analysis aligned to NIST SP 800-53 expectations. ¹

Practical execution plan (30/60/90-day)

First 30 days (Immediate stabilization)

• Assign a control owner (Security Ops or Endpoint Engineering).
• Write the SI-3(4) operating procedure: privileged roles, direction method, and scope. ²
• Inventory malware protection mechanisms and management planes in scope.
• Confirm RBAC and MFA for the security console; eliminate shared admin accounts where found.
• Identify top exception categories (legacy servers, offline enclaves, third-party-managed environments) and start an exception register.

By 60 days (Technical enforcement + logging)

• Push policies that prevent standard users from changing update settings.
• Enable tamper protection and uninstall protections across managed fleets.
• Standardize update sources and restrict egress where feasible.
• Turn on and centralize audit logs for admin actions and policy changes.
• Define change control triggers for update-related policy changes and start capturing tickets.

By 90 days (Prove it works, then operationalize)

• Run a repeatable control test and save results.
• Build an “update health” report and a drift review workflow for security operations.
• Close or time-box major exceptions; add compensating controls where closure takes longer.
• Implement recurring evidence capture in Daydream (or your GRC system) so you can produce the same artifacts each assessment cycle without rebuilding the story. ²

Frequently Asked Questions

Does SI-3(4) ban automatic signature updates?

No. Automatic updates can satisfy SI-3(4) if a privileged user configures, approves, and controls the update policy and users cannot override it. Keep evidence that the privileged role set the policy and that endpoints cannot change it. ²

Who counts as a “privileged user” for this requirement?

A privileged user is any role with administrative authority to change malware protection update behavior (console admin, endpoint security admin). Define it in your procedure and tie it to IAM roles and access reviews. ²

If users have local admin, can we still comply?

It’s difficult. Local admin commonly enables disabling or tampering with agents and update settings. If you cannot remove local admin everywhere, use tamper protection, JIT elevation, and monitoring for configuration drift.

Are engine upgrades and agent upgrades included, or only signature updates?

Treat them all as in scope: signatures, engines, agent versions, and update source configuration. This approach aligns to the phrase “malicious code protection mechanisms” and reduces debate during audits. ²

What evidence is usually most persuasive to auditors?

Console audit logs that show a named privileged identity changed update policy, plus endpoint security policy exports showing standard users cannot alter update settings. Pair that with a change record for the same event.

How do third parties fit in if they manage our endpoint security tool?

Require the third party to perform update actions only under authorized direction (your approval model) and to provide logs that identify the privileged operator. Contract terms should require audit logs and access control details consistent with your SI-3(4) procedure. ²

Footnotes

1. NIST SP 800-53 Rev. 5

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