This post provides a pragmatic, step-by-step implementation checklist to enforce safeguarding of Controlled Unclassified Information (CUI) for employees working at alternate sites — directly mapped to NIST SP 800-171 Rev.2 / CMMC 2.0 Level 2 control PE.L2-3.10.6 — with practical configuration details, small-business examples, and evidence artifacts you can use for assessments and audits.
Why this control matters and the risk of not implementing it
If CUI is processed, stored, or accessed outside company facilities without consistent safeguards, an organization risks data exfiltration, accidental disclosure, contract non‑compliance, and loss of DoD/prime contracts. For a small business that wins a subcontract to handle drawings or program data, a single compromised remote laptop or unsecured home Wi‑Fi can result in a reportable incident, expensive remediation, contract suspension, and reputational damage. Non‑implementation also impacts audit evidence: missing remote work policies, lack of endpoint encryption records, or gaps in remote access logging are common findings during CMMC assessments.
High-level implementation approach
Adopt a layered plan combining policy, technical controls, physical protections, training, and monitoring. The checklist below is structured so a small IT/security team can prioritize low-effort, high-impact controls first (policy + MFA) and then implement technical hardening (EDR, VPN/VDI), logging, and continuous validation. For each step I include suggested artifacts you should maintain for auditors and real-world configurations that work on modest budgets.
Step 1 — Policy, agreements, and scope (what to write and collect)
Create a Remote Work/CUI at Alternate Sites policy and a Remote Work Agreement that every remote worker signs. Policy must define CUI types, approved locations (home office, co‑working exceptions), device ownership rules (company‑owned required for CUI access unless approved), and minimum physical controls (locked room, screen privacy). Artifact examples: signed remote work agreements, a CUI handling SOP, and a roster of authorized alternate work locations. For a 12-person contractor, a simple CSV mapping employee → approved device serial → agreement signature date is acceptable evidence.
Step 2 — Identify, classify, and minimize CUI exposure
Inventory where CUI is stored and accessed. Apply data classification and labeling (electronic metadata + human-readable banners). Use Microsoft Purview, Google DLP, or manual file naming conventions if budgets are tight (e.g., CUI_XXX prefix). Reduce attack surface by limiting CUI access to specific accounts/groups and by avoiding local copies on unmanaged devices. Example: configure SharePoint/OneDrive to disallow sync for CUI libraries, forcing remote workers to use browser or VDI access so files are not cached locally.
Step 3 — Technical controls for secure access to alternate sites
Require MFA for all CUI access, enforce device health checks via conditional access, and use a hardened remote access model: either a managed VPN (IKEv2/IPsec or TLS; no PPTP), or preferably a VDI/Azure Virtual Desktop solution where CUI never leaves the server. Disable split tunneling for VPNs and require TLS 1.2+/1.3. Enforce full disk encryption (BitLocker with TPM+PIN, FileVault) and centrally manage devices with MDM (Intune, Jamf) and EDR (CrowdStrike/SentinelOne/Microsoft Defender). Configure DLP policies to block uploads to unmanaged personal cloud storage and disable local printing of CUI if the policy requires. For a small business: use Azure AD Conditional Access + Intune + Microsoft 365 DLP to achieve many requirements without large capital expense.
Step 4 — Network and physical environment hardening at alternate work sites
Define minimum network configuration guidance: WPA3 (or WPA2‑AES) on home routers, change default admin passwords, firmware updates enabled, and guest Wi‑Fi segmented from work devices. Provide checklists or a short “home office hardening” guide that employees must follow and attest to quarterly. If employees use personal hotspots, limit CUI access to very specific tasks or block entirely. For shared spaces or co‑working, require private meeting rooms for CUI discussions and use privacy screens and timed auto‑lock on devices (max 5 minutes inactivity).
Step 5 — Monitoring, logging, and incident preparedness
Centralize logs for remote access, authentication, endpoint alerts, and cloud storage access into a SIEM or log repository (Splunk, Azure Sentinel, or lightweight syslog/SIEM-as-a-Service). Keep authentication logs, VPN/VDI logs, device management compliance status, and DLP incidents for at least 1 year unless contract specifies otherwise. Define and exercise incident response playbooks for remote incidents (lost/stolen device, suspected compromise, unauthorized disclosure). Evidence: log retention settings, recent incident runbook, and results from a tabletop exercise involving a remote worker scenario.
Step 6 — Training, verification, and continuous improvement
Deliver role-based training that includes CUI marking, remote‑site security controls, and reporting requirements; retain completion records. Conduct periodic spot checks: remote device inventory audits, posture scans (vulnerabilities, EDR status), and occasional remote interviews where the employee demonstrates their workspace and device compliance via a short video or picture. Run quarterly vulnerability scans and monthly patch cycles (critical patches within 30 days) for remote endpoints. For small businesses, document each check as evidence — a dated spreadsheet or ticketing system entry tied to the employee ID is sufficient.
Validation, evidence collection and audit tips
Collect artifacts proactively: signed policies and agreements, device manifests and MDM enrollment records, conditional access and VPN config screenshots, DLP rule exports, SIEM logs with search queries and timestamps, training completion reports, and incident playbooks/tests. During pre‑assessment, run a gap analysis against SP 800‑171 requirement 3.10.6 and CMMC Level 2 practices, then remediate high‑risk gaps before the formal assessment. Keep a continuous evidence folder (PDFs and export CSVs) indexed by requirement to speed audits.
Summary: Implementing PE.L2-3.10.6 for alternate work sites is achievable for small businesses by combining clear policies and signed agreements, strict identity and device controls (MFA, MDM, EDR, disk encryption), secure remote access (VPN/VDI, no split tunneling), DLP and logging, plus regular training and verification. Prioritize high‑impact, low‑cost actions first (MFA, encryption, signed agreements), document everything, and build an evidence collection habit so you can both reduce risk and demonstrate compliance to assessors and contracting officers.
