8 Essential Microsoft Exchange Online Security Tips and Best Practices

8 Essential Microsoft Exchange Online Security Tips and Best Practices

December 18, 2022

Email is one of the most important tools for communication, collaboration, and productivity for businesses. That's why it's essential to ensure your email system is secure and compliant with industry regulations. 

Microsoft Exchange Online is a cloud-based email system that provides robust security features to protect your business data and communications. 

In this article, we'll explore why organizations should use Exchange Online over on-premises Microsoft Exchange, talk about the most important security features in Exchange Online, and discusses best practices for enhanced security.

We'll also talk about security monitoring and provide a full-fledged framework for responding to security incidents in Exchange Online. 

Why Use Exchange Online Over On-Premises Exchange Servers?

In an article published in October 2022, WIRED laid down the case for why businesses should migrate their email servers to the cloud. It cited an earlier attack perpetrated by Hafnium in 2021 which exploited zero-day vulnerabilities in Microsoft Exchange to compromise more than 30,000 servers across the US alone. 

The reason? Installing a patch in on-premises Microsoft Exchange is a slow and taxing process. It’s a time-consuming endeavor with a massive learning curve, not to mention the fact that it can sometimes take Microsoft months to release patches for vulnerabilities that could compromise your Exchange server.

In fact, some might argue that Microsoft Exchange is a “legacy product” that’s slowly being sunsetted in favor of the cloud-based Exchange Online. Exchange Online comes with much better security implementation and essential features to keep hackers at bay. Here’s a quick overview of the advantages of using Exchange Online over on-premises Microsoft Exchange: 

  • Advanced Security: Exchange Online provides advanced security features such as multi-factor authentication, data encryption, malware and spam protection, intrusion detection/prevention systems, and more. These features help protect your organization from malicious actors and reduce the risk of data breaches.
  • Automated Updates: Microsoft regularly updates the Exchange Online platform to ensure that the latest security measures are in place. This takes away the burden from the technical staff of having to manually update the system on a regular basis.
  • Reduced Costs: By using Exchange Online, organizations can cut costs associated with hardware, software, and infrastructure maintenance for on-premise exchange servers. Additionally, businesses can save money by not having to hire IT staff to manage their on-premise exchange server. 
  • increased Reliability: Exchange Online is hosted in Microsoft’s cloud environment which ensures that your data is always available and secure regardless of what may happen with an on-premise server or network issue. 

The Most Important Security Features in Exchange Online

Exchange Online provides an array of security features to keep your data safe, including multi-factor authentication, advanced encryption, malware protection, and spam filtering. 

It also offers a number of features to ensure a better security posture, such as email archiving, data loss prevention (DLP), and eDiscovery. All of this comes on top of built-in security tools like anti-phishing policies and mailbox auditing to help protect against attacks.

Want to know more about the top security features of Exchange Online? Here they are:

Multi-Factor Authentication: This functionality is designed to prevent phishing attacks and unauthorized access to Exchange Online through Azure Active Directory (AD). It requires users to provide multiple authentication factors for permission to access sensitive data.

Data Loss Prevention (DLP): DLP is a security setting that helps protect sensitive information from threats like ransomware by monitoring and controlling data in emails, documents, and other content shared within Exchange Online.

Malware Protection: Exchange Online includes a built-in anti-malware application that scans incoming emails for malicious content, blocking any threats as soon as they are detected. It offers multilayer protection by scanning for viruses across all known databases.

Advanced Threat Protection (ATP): ATP helps protect against sophisticated cybersecurity attacks by using machine learning algorithms to detect suspicious activities and block phishing emails before they reach user inboxes. 

Secure Email Gateways: Exchange Online also includes secure email gateways which help protect against external threats such as phishing, spam, and other malicious content sent from outside of the organization’s network.

The Top Exchange Online Security Best Practices

However, Exchange Online security isn’t all plug-and-play. You have to manually configure these features and use them in combination with industry-wide security best practices to get the desired effect. Here are the most important Exchange Online security best practices to know:

Enable Multi-Factor Authentication (MFA)

MFA requires users to provide two or more factors of authentication, such as a password and a one-time code sent to their mobile device, to access their accounts. This prevents unauthorized access even if someone obtains a user’s password.

Use Conditional Access Policies

Exchange Online provides the ability to set up conditional access policies that require users to meet certain criteria before they can access their accounts. For example, these policies can require users to be located in specific locations, use specific devices, or use a specific level of authentication before they can log in.

Implement Mailbox Auditing

Mailbox auditing allows administrators to track user activity in Exchange Online mailboxes and detect suspicious behavior. It also helps administrators detect compromised accounts by allowing them to review the recent activity of any user account.

Monitor for Suspicious Activity

Exchange Online provides built-in reports and alert policies that allow administrators to monitor for suspicious activity such as excessive login attempts or unusual data transfers from mailboxes. These reports can help protect against malicious actors trying to gain access or exfiltrate data from an organization’s environment.

Configure Secure Connectivity

You should configure secure connectivity between on-premises and cloud environments by using IPsec or TLS tunneling protocols when connecting Exchange Online with other services such as Outlook Web App (OWA). That will help protect against man-in-the-middle cyberattacks and other threats targeting communication between on-premises and cloud environments.

Implement Role-Based Access Control (RBAC)

It’s important to limit users’ access rights within Exchange Online based on their roles within the organization. You don't want unauthorized users accessing sensitive information or making changes they should not be able to make. 

Configure a Secure Email Gateway

The secure email gateway is a cloud-based service that helps protect inbound and outbound emails from malware, phishing, and other threats.

How to Monitor Security in Exchange Online

Once you have established a modern security posture to protect your organization’s email, it’s also important to regularly monitor and track your cybersecurity setup to ensure things are working as they should. Here are four things you should monitor through Exchange Online:

  • Use the audit log provided by Office 365 to track user activities in Exchange Online. It includes information such as mailbox logins, sent emails, deleted items, and more.
  • Scan incoming emails for malicious content and block any suspicious messages using Exchange Online Protection (EOP).
  • Configure mailbox auditing to track mailbox activity such as login attempts, item creations and deletions, permission changes, and more.
  • Use the admin center for SharePoint Online to monitor the external sharing of documents and other content within your organization’s sites.

Responding to Exchange Online Security Incidents

But what if your system has already been compromised? Here’s a step-by-step framework for responding to Exchange Online security incidents once they have already happened, with the goal of minimizing damage and remediating systems as quickly as possible:

  1. Identify the Incident: Establish what type of security incident has occurred, such as a malicious email, phishing attack, or data breach.
  2. Secure the Environment: Immediately take steps to secure the environment by disabling accounts, changing passwords, and blocking access to compromised systems.
  3. Collect Evidence: Gather evidence to help determine the extent of the incident and identify potential malicious actors. This can include system logs, emails, audit trails, and any other relevant data sources.
  4. Investigate and Contain: Conduct an investigation into the incident and take further action to contain it by disabling accounts or blocking access as needed.
  5. Communicate with Stakeholders: Notify stakeholders such as IT staff, legal representatives, and management about the incident and provide timely updates throughout the process of resolution. 
  6. Remediate Damage: Take steps to remediate any damage caused by the security incident, such as restoring data or systems affected by it. 
  7. Implement Prevention Measures: Update policies and procedures to address security issues that led to or were affected by the incident, such as implementing two-factor authentication or strengthening password requirements for users.

Using Simeon to Automatically Configure Your Exchange Online Security Posture

Simeon Cloud is a configuration management solution that offers complete control over the security setup of your Microsoft 365 tenants. It lets you configure, manage, and modify a host of different security policies across M365, including Exchange Online.

As of right now, Simeon allows you to configure more than 35 different security and compliance settings in Exchange Online, including Admin Audit Log Config and Malware Filter Policies.

Why use Simeon to manage your Exchange Online security configurations? It offers features like one-click backups, secure baselines, real-time monitoring, periodic reports, and multi-tenant management all through a powerful no-code interface with a minimal learning curve.

Want to learn more about how Simeon can improve your Exchange Online security posture? Sign up for a free one-on-one demo!