--- title: "Microsoft 365 Security for SMBs | EFROS" description: "Harden Microsoft 365: identity, MFA, conditional access, email security, DLP, Defender XDR. Built for regulated SMB, mid-market, and enterprise tenants." canonical: https://efros.com/security/microsoft-365/ --- - [Home](https://efros.com/) - /[Security](https://efros.com/security/) - /Microsoft 365 Security Service · Microsoft 365 Security # Microsoft 365 Security for small and mid-sized businesses. Most SMB breaches start with email. We harden Microsoft 365 against the attacks that reach mid-market companies: business email compromise, credential theft, mailbox-forwarding-rule exfiltration, and unmanaged personal devices. The tenant stays friendly enough that your users won't file rebellion tickets. By [Stefan Efros](https://www.linkedin.com/in/stefanefros-cyberdefense/), CEO & Founder, EFROS Updated · July 25, 2026 ## Where the real risk lives. 01 ### Most SMB breaches start with email Phishing and business email compromise (BEC) are the dominant initial-access vectors against mid-market companies. A single weak account is enough. 02 ### Default settings are not hardened Microsoft 365 ships with sensible defaults for usability, not for resisting a determined attacker. MFA is not on for every account out of the box. 03 ### Conditional Access is unscoped Without policies tied to risk signals, sign-ins from anywhere with the right password succeed. Attackers know this. 04 ### Mailbox forwarding rules are unmonitored A common BEC step: attacker sets a forwarding rule on a compromised mailbox to read replies for weeks. No one notices unless someone is watching. 05 ### SPF / DKIM / DMARC fail open Most domains have at least one of the three misconfigured. Attackers spoof the domain externally; your tenant accepts internal-looking phish. 06 ### Devices are unmanaged Personal laptops and unmanaged phones touching corporate Microsoft 365 with no compliance enforcement. One ransomware run away from a tenant-wide blast. ## What's included. Delivered under the Secure Operations or Fortress SOC tier. License-tier dependent (Microsoft 365 Business Premium covers most; E5 unlocks the full Defender XDR stack): - CIS Microsoft 365 Foundations Benchmark baseline - Conditional Access policies (location, device, risk-based) - Identity Protection (sign-in risk + user risk policies) - Microsoft Defender for Office 365 (Safe Links, Safe Attachments, anti-phish) - Microsoft Defender for Endpoint (EDR + ASR rules) - Microsoft Defender for Cloud Apps (CASB + shadow-IT visibility) - Intune device management (Windows, macOS, iOS, Android) - Data Loss Prevention (DLP) policies on email + SharePoint + OneDrive - SPF, DKIM, DMARC alignment + DMARC reporting - Mailbox audit logging + forwarding-rule monitoring - Privileged Identity Management (PIM) for admin roles - Quarterly security posture review against CIS + Microsoft Secure Score ## Why EFROS for Microsoft 365. Our engineers hold individual Microsoft certifications that map directly to this work, including Microsoft 365 Enterprise Administrator Expert, Microsoft Identity and Access Administrator, and Defender / Sentinel specializations. Specific credentials and vendor partnership letters are documented and provided under NDA via the Trust Center. We configure the tenant the way Microsoft's own security architects would, and we keep operating it afterwards. Plenty of MSPs will stand it up and hand it back. We stay on the keys. Your configuration lives in version control. Conditional Access policies, DLP rules, Defender configurations, all of it. The day you leave us (it happens, occasionally), you take a clean tenant and the as-built docs with you. No vendor lock, and nothing for the next provider to re-discover. ## Frequently asked. ### Do you replace Microsoft 365 with something else? + No. We harden your existing Microsoft 365 tenant. The licensing, the data, and the user experience stay the same. Configuration, policies, and detection content change. ### Which Microsoft 365 license tier do we need? + Microsoft 365 Business Premium covers most of what we deploy on the Secure Operations tier. Microsoft 365 E5 unlocks the full Defender XDR + Sentinel stack used at the Fortress SOC tier. ### Will users feel the change? + Mostly through MFA prompts and Conditional Access. We schedule the rollout, train end users, and run the first 30 days with extra support to keep helpdesk volume manageable. ### Do you handle the migration if we're still on Google Workspace? + Yes. We do greenfield Microsoft 365 deployments and Google-Workspace-to-Microsoft-365 migrations under the same engagement. Mailboxes, files, identity, and devices. ### Can you support hybrid identity with on-premise Active Directory? + Yes. Entra Connect, password hash sync or pass-through authentication, hybrid Conditional Access, and on-prem device join are all supported. ### Who offers Microsoft 365 security and email protection for companies in Chicago? + EFROS delivers Microsoft 365 security and email protection to Chicago-area companies remotely, as a service-area business with no local office required. We harden your tenant with Microsoft Defender XDR, Conditional Access paired with phishing-resistant MFA, and Purview DLP, then lock down email with SPF, DKIM, and DMARC alignment plus mailbox and forwarding-rule monitoring to stop business email compromise. Our practice is SOC 2-aligned and ISO 27001-aligned, mapped to the NIST frameworks, and backed by a contractual 4-hour incident-response SLA. [Run Free Security Score](https://efros.com/tools/security-scan/) [Talk to a Microsoft 365 specialist](https://efros.com/contact/?type=microsoft-365) Related programs [### Managed Detection & Response EDR + XDR + SOAR layered with Defender XDR for unified M365 + endpoint detection.Open→](https://efros.com/security/mdr/) [### Managed SIEM Sentinel-piped M365 audit logs, custom detection content, alerting tuned for tenant-specific risks.Open→](https://efros.com/security/managed-siem/) [### Incident Response Retainer Pre-engaged commander for BEC, OAuth-grant phishing, token theft, tenant-wide takeover.Open→](https://efros.com/security/incident-response/) [### AI Governance (Copilot) M365 Copilot risk classification, tenant configuration, audit logs piped to SIEM, quarterly governance reporting.Open→](https://efros.com/services/ai-governance/) Related EFROS resources ## M365 security stack [### M365 security checklist (free) Tenant hardening across Entra ID, Exchange, SharePoint, Teams, Defender, Purview.Open→](https://efros.com/resources/microsoft-365-security-checklist/) [### DMARC rollout Email auth piece of the M365 hardening.Open→](https://efros.com/resources/dmarc-rollout-guide/) [### MDR for M365 telemetry 24/7 SOC ingests M365 audit logs and Defender alerts.Open→](https://efros.com/security/mdr/) [### Zero Trust + Conditional Access M365 hardening within a broader Zero Trust architecture.Open→](https://efros.com/security/zero-trust/) [### vCISO owns M365 program Named operator runs M365 governance, training, audit-log review.Open→](https://efros.com/security/vciso/) [### BEC incident in M365 What a real BEC fraud looks like and how M365 hardening prevents it.Open→](https://efros.com/incident-stories/bec-fraud-at-manufacturer/)