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. However, with great power comes great responsibility (as Uncle Ben said in Spiderman). M365 also posesseveral security challenges that can expose your organisation to data breaches, cyberattacks, and compliance issues. In this blog post, we will discuss the top M365 security issues and how you canaddress them with the help of our cybersecurity company.

Top 10 M365 security issues

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.

Privilege abuse

Users may have more permissions than they need, which can increase the risk of data breaches or privilege escalation by malicious actors.

Global administrator account breaches

Hackers may target administrative accounts to gain access to elevated privileges and compromise the entire M365 environment.

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.

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.

Testing and validation

Thoroughly test and validate the migrated data and applications to identify any issues or inconsistencies. Conduct user acceptance testing (UAT) to ensure that everything is functioning as expected. This step will enable you to address any potential problems before the final migration, minimizing disruptions and ensuring a positive user experience.

Mailbox folder permission abuse

Attackers may exploit mailbox folder permissions to access sensitive emails or attachments without triggering alerts or audit logs.

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.

Golden SAML

Attackers may forge SAML tokens to impersonate legitimate users and bypass authentication mechanisms in M365 or other cloud services.

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.

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

Identity and Access Management

Enforce strong password policies, enable multi-factor authentication, limit privileged accounts, monitor sign-in activities, and revoke suspicious OAuth grants.

Device Management

Intune allows IT administrators to enroll devices into the management system, ensuring that only authorized devices can access corporate resources. Devices that do not meet the organization security and compliance policies can be blocked from accessing sensitive data and services. With Intune, IT administrators can apply MAM policies to protect corporate data without managing the entire device. This allows them to secure business data within M365 apps on the device, even if it’s a personal device.

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 defender for cloud, 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

AttackeUse Microsoft 365 Security Centre and Microsoft 365 Compliance Centre to gain visibility and control over your security and compliance settings, alerts, and actions.rs may exploit mailbox folder permissions to access sensitive emails or attachments without triggering alerts or audit logs.

Conduct security assessments

Regularly perform security assessments and penetration testing to identify vulnerabilities and weaknesses in your M365 environment.