Microsoft 365 Security Hardening SOP¶

Sub-procedure for Operate pillar managed services - M365 security configuration implementation

Service Pillar: Operate Service Category: Microsoft 365 Security Parent SOP: Cloud Operations SOP Engagement Type: Implementation / Remediation

Overview¶

Implementation of security hardening configurations for Microsoft 365 environments based on assessment findings, Microsoft security benchmarks, and industry best practices. This procedure covers the systematic application of security controls across identity, data protection, and threat prevention domains.

Scope¶

Pillar: Operate (Managed Services) Service Area: Microsoft 365 Security Hardening

In Scope¶

Azure AD / Entra ID security configuration
Exchange Online protection hardening
SharePoint/OneDrive access controls
Teams security settings
Conditional Access policy implementation
DLP policy deployment
Microsoft Defender configuration

Out of Scope¶

Custom application development
Third-party security tool integration
Endpoint device enrollment (separate engagement)

Prerequisites¶

Completed M365 Security Assessment
Approved remediation roadmap with prioritization
Microsoft 365 Global Admin access (or delegated admin)
Change management approval from client
Rollback plan documented
User communication plan approved
Maintenance window scheduled (if required)

Procedure¶

Step 1: Pre-Implementation Validation¶

Objective: Confirm readiness and minimize implementation risk

Activities: 1. Verify current configuration baseline (export settings) 2. Confirm licensing supports planned features 3. Validate test accounts for verification 4. Review dependencies and potential impacts 5. Confirm rollback procedures are documented 6. Schedule implementation windows with client

Risk Mitigation: | Risk | Mitigation | |------|------------| | User lockout from MFA | Staged rollout, emergency access accounts | | Business disruption | Off-hours implementation, pilot groups | | Data access issues | Test with pilot users first |

Duration: 2-3 hours

Step 2: Identity Hardening¶

Objective: Implement authentication and access controls

Configuration Checklist: - [ ] Enable Security Defaults (if no Conditional Access) - [ ] Configure MFA enforcement for all users - [ ] Block legacy authentication protocols - [ ] Implement Conditional Access policies: - [ ] Require MFA for admin roles - [ ] Block sign-ins from risky locations - [ ] Require compliant devices (if Intune) - [ ] Session timeout policies - [ ] Enable Azure AD Password Protection - [ ] Configure Privileged Identity Management (PIM) - [ ] Disable user consent for applications - [ ] Enable sign-in risk policies

Implementation Order: 1. Emergency access accounts (break-glass) 2. Admin MFA enforcement 3. Conditional Access - pilot group 4. Conditional Access - production rollout 5. Legacy auth blocking (phased)

Duration: 4-8 hours (depending on scope)

Step 3: Email Security Hardening¶

Objective: Configure Exchange Online and Defender for Office 365 protections

Configuration Checklist: - [ ] Configure anti-phishing policies - [ ] Enable impersonation protection - [ ] Configure mailbox intelligence - [ ] Set spoof intelligence actions - [ ] Enable Safe Attachments - [ ] Dynamic Delivery or Block mode - [ ] Enable for SharePoint/OneDrive/Teams - [ ] Enable Safe Links - [ ] Real-time URL scanning - [ ] Track user clicks - [ ] Block malicious URLs - [ ] Configure anti-spam policies - [ ] Enable DMARC, DKIM, SPF validation - [ ] Configure mail flow rules for external tagging - [ ] Disable auto-forwarding to external domains

Verification: - Send test phishing simulation - Verify quarantine functionality - Test external email tagging

Duration: 3-4 hours

Step 4: Data Protection Implementation¶

Objective: Deploy data classification and loss prevention controls

Configuration Checklist: - [ ] Deploy sensitivity labels - [ ] Define label taxonomy - [ ] Configure protection settings (encryption, marking) - [ ] Publish labels to users - [ ] Configure DLP policies - [ ] PII protection (SSN, credit cards) - [ ] Financial data protection - [ ] Healthcare data (if applicable) - [ ] Custom sensitive info types - [ ] Configure external sharing restrictions - [ ] SharePoint sharing limits - [ ] OneDrive sharing controls - [ ] Teams guest access policies - [ ] Enable audit logging - [ ] Configure retention policies

Duration: 4-6 hours

Step 5: Collaboration Security¶

Objective: Secure Teams and SharePoint environments

Configuration Checklist: - [ ] Configure Teams security settings - [ ] Guest access policies - [ ] Meeting security defaults - [ ] External chat restrictions - [ ] App permission policies - [ ] SharePoint security settings - [ ] Site creation restrictions - [ ] Default sharing link type - [ ] Access control for unmanaged devices - [ ] OneDrive security settings - [ ] Sync client restrictions - [ ] Sharing defaults

Duration: 2-3 hours

Step 6: Post-Implementation Verification¶

Objective: Validate configurations and document completion

Activities: 1. Run Secure Score comparison (before/after) 2. Test all implemented controls 3. Verify user access is functioning 4. Document all configuration changes 5. Update client documentation 6. Conduct user impact assessment 7. Schedule follow-up review (30 days)

Verification Checklist: - [ ] MFA working for all user types - [ ] Conditional Access policies triggering correctly - [ ] Email protections functioning - [ ] DLP policies alerting/blocking as expected - [ ] External sharing controls working - [ ] No unexpected user lockouts