How to Secure Your Microsoft 365 Environment

microsoft 365 security

Securing your M365 Environment: A Guide for Business

Microsoft 365 (M365), formerly known as Office 365, is an extremely popular cloud-based productivity suite that offers various applications and services for businesses of all sizes. Microsoft 365 includes Office 365 web-apps: Word, Excel, Outlook, PowerPoint, OneNote, as well as Exchange, Teams, SharePoint, OneDrive, Forms and Visio. However, as Uncle Ben said in Spiderman “with great power comes great responsibility”. M365 also poses several security challenges that can expose your organisation to data breaches, cyberattacks, and compliance issues. So how do you go about securing your M365 environment? In this blog post, we will discuss the top M365 security issues and how you can address them.

Top 10 Microsoft 365 Security Issues

Firstly, let us understand the different security issues that can arise with M365:

  1. Unauthorised or external file sharing: Users can share files or folders with people outside of the organisation, which can expose sensitive data to unauthorised access or leakage.
  2. Privilege abuse: Users may have more permissions than they need, which can increase the risk of data breaches or privilege escalation by malicious actors.
  3. Global administrator account breaches: Hackers may target administrative accounts to gain access to elevated privileges and compromise the entire M365 environment.
  4. Lack of data protection policies and training: Organisations may not have adequate rules or guidance for employees on how to handle sensitive data, such as passwords, software updates, multi-factor authentication, personal information sharing, etc.
  5. Avoiding detection: Attackers may use stealthy techniques to evade security controls and remain undetected in the M365 environment, such as using compromised credentials, abusing OAuth tokens, or exploiting misconfigurations.
  6. Mailbox folder permission abuse: Attackers may exploit mailbox folder permissions to access sensitive emails or attachments without triggering alerts or audit logs.
  7. Hijacking enterprise applications and app registrations: Attackers may create or modify enterprise applications or app registrations to gain persistent access to M365 resources or data.
  8. Golden SAML: Attackers may forge SAML tokens to impersonate legitimate users and bypass authentication mechanisms in M365 or other cloud services.
  9. Active Directory Federation Services replication: Attackers may replicate Active Directory Federation Services (ADFS) configuration data to compromise federated identities and access M365 or other cloud services.
  10. Big data exfiltration: Attackers may use various methods to extract large amounts of data from M365, such as using PowerShell scripts, OneDrive sync clients, or third-party applications.


Mitigating Microsoft 365 threats:

To mitigate these threats, organisations should implement a comprehensive security strategy that covers the following aspects:

  • Identity and access management: Enforce strong password policies, enable multi-factor authentication, limit privileged accounts, monitor sign-in activities, and revoke suspicious OAuth grants.
  • Data protection: Encrypt sensitive data at rest and in transit, apply data loss prevention policies, restrict external sharing, and audit data access and usage.
  • Threat protection: Enable Microsoft Defender for Office 365 and Microsoft Defender for Identity to detect and respond to malicious activities, such as phishing, malware, or lateral movement.
  • Security posture management: Use Microsoft Secure Score and Microsoft Compliance Score to assess and improve your security and compliance posture and remediate any identified gaps or issues.
  • Security operations: Use Microsoft 365 Security Centre and Microsoft 365 Compliance Centre to gain visibility and control over your security and compliance settings, alerts, and actions.

How can CommSec Help?

As you can see, securing your M365 environment is not an easy task. It requires a comprehensive and proactive approach that covers all aspects of your cloud security posture. That is why we offer an M365 Security Assessment that can help you identify and remediate your M365 security gaps and vulnerabilities.

CommSec’s M365 Security Assessment includes:

  • A thorough review of your M365 configuration and settings.
  • A detailed report of your M365 security issues and recommendations.
  • A prioritised action plan to improve your M365 security posture.
  • A follow-up consultation to assist you with the implementation.

Next Steps:

Securing your Microsoft 365 environment is of utmost importance in today’s cyber-threat landscape. While M365 offers a wide range of powerful tools for businesses, it also presents several security challenges that require careful attention and proactive measures. Addressing issues such as unauthorised file sharing, privilege abuse, and administrative account breaches is vital to protect sensitive data and maintain compliance. By implementing a comprehensive security strategy encompassing identity and access management, data protection, threat protection, security posture management, and effective security operations, organisations can significantly reduce the risk of data breaches and cyberattacks in their M365 environment.

At CommSec, we understand the complexity of M365 security and offer a dedicated M365 Security Assessment to help you identify and address potential vulnerabilities. Our expert team will conduct a thorough review of your M365 configuration, provide a detailed report with actionable recommendations, and assist you in implementing the necessary improvements. With a proactive approach to M365 security, you can fortify your cloud environment and safeguard your organisation against potential threats. Protect your business with CommSec’s M365 Security Assessment today and take a decisive step towards a more secure and resilient digital future.

Read the M365 Security Assessment solution brief here

M365 Security Assessment