Microsoft 365 is at the heart of the business for many SMEs: emails, documents, Teams conversations and user account management all go through the same platform. This concentration makes the M365 environment an attractive target for attackers. One-off security configuration checks are not enough, as threats evolve and your environment changes daily.
In this article, we'll walk you through how to build an M365 security monitoring model that works for your business. You'll learn how to identify key risks, automate alerts and create clear remediation paths for your rapidly growing teams. Vahti provides SMEs with the tools to monitor their M365 environment without deep technical expertise.
Microsoft 365 environments are under constant attack. According to the Finnish National Cyber Security Centre, more than 330 M365 account compromises were reported in Finland in 2025. The situation has accelerated, with 121 incidents reported in a single month in October 2025.
Attackers are not only targeting large enterprises. SMEs are an attractive target because they often have limited resources for monitoring. An attack can start with a single hijacked account and quickly spread throughout an organisation.
A hijacked account gives an attacker access to emails, files and Teams conversations. The attacker can send credible phishing messages to colleagues and customers using the correct email address. This makes the scams difficult to identify.
Billing scams are common: the attacker monitors email traffic, identifies payment-related conversations and sends a fake invoice from an address that looks real. The damage can be significant before the breach is even detected.
The M365 environment changes, even if you do nothing. Microsoft regularly releases new features and security settings. Users add applications, share files and change settings. Each change can open a new risk path.
Unchecked, these changes will go unnoticed. Monitoring reveals anomalies and allows you to react before the risk causes harm.
The risks in an M365 environment are similar across organisations of all sizes. By prioritising correctly, you can significantly reduce risk without heavy projects.
A user account is the most common route into the M365 environment. According to Microsoft's Digital Defense Report 2025, more than 97% of identity attacks are based on password attacks that try weak or reused passwords. Multi-factor authentication (MFA) prevents more than 99 percent of unauthorized login attempts.
The risk increases if MFA is not comprehensively implemented or is implemented too loosely. Administrator accounts in particular require stronger protection, as they give an attacker broad access rights.
Phishing is still the most common form of attack. In 2024, as many as 74% of organisations reported being the target of a phishing attack. AI-generated phishing messages are becoming more credible and harder to identify.
Business Email Compromise (BEC) scams exploit hijacked accounts. The attacker poses as a trusted individual and requests urgent payment or release of information. Without clear policies and verification procedures, these scams are all too often successful.
SharePoint and OneDrive make sharing easy. The risk arises when sharing is not controlled and monitored. Typical problems include:
Bans alone will not solve these problems. You need a model where you define the limits of permissible sharing and monitor compliance.
Users can connect third-party applications to their M365 environment that are granted extensive rights to data. Without control, you don't know which applications are in use and what rights they have. Vahti shows you all the applications that are connected and reveals the risks associated with them.
An effective monitoring model combines technical controls, automated alerts and clear policies. Start with the basics and expand step-by-step.
Identity is the foundation of M365 security. Start with these steps:
Email is the most common avenue of attack. Strengthen your protection with these steps:
Manage information sharing and storage with clear policies:
Manual monitoring does not scale to the needs of a growing organization. Automation ensures that critical events are detected in a timely manner.
Microsoft 365 provides built-in alerts that you can enable in the Defender portal. Configure alerts for these events:
Alerts are only useful if they are acted upon. Assign an owner and define a response procedure for each alert.
Vahti provides an easy way for SMEs to monitor their M365 environment. Vahti analyses the security settings and risk signals in your environment, prioritises findings in order of criticality and provides clear remediation instructions. You don't need to be an IT expert to understand what to do.
Vahti monitors logins, permissions, applications and settings around the clock. Anomalies are detected before they become problems. This frees up your time to focus on business instead of security concerns.
Risk detection is just the beginning. Real value is created when risks are also remediated. Clear remediation paths ensure that action follows from the findings.
An effective remediation process includes these steps:
For each risk, Vahti shows what needs to be done and how. The remediation instructions are written in plain language, so you don't need deep technical knowledge. You can complete the remediation yourself or pass the remediation request on to an expert.
This model ensures that risks are not left hanging. Every finding leads to a concrete action and a documented outcome.
When an anomaly is detected, responding quickly limits damage. Have a plan of action in place so that in the event of a crisis, you don't have to think about the next step.
Critical first steps after an account compromise:
Rehearse incident scenarios before they happen. Short tabletop exercises running through a realistic account breach scenario will expose weaknesses in the process. Correct shortcomings before a real crisis occurs.
Technical controls are essential, but they alone are not enough. Staff performance is often the deciding factor in whether or not an attack succeeds.
Focus on the practical situations that staff face in their day-to-day work:
Role-specific training increases effectiveness. Finance staff face different scams than the sales team. Tailor examples to the target audience.
One-off training does not change behaviour permanently. Short, regular reminders and simulated phishing tests build lasting vigilance. Track how staff skills develop over time.
Launching monitoring does not require a large investment or IT department. Start with the basics and expand as needed.
These steps will get you started:
Connect Vahti to your M365 environment in minutes. Simply give Vahti read-only access through the official Microsoft interfaces. Vahti does not make any changes to your environment, but provides a view of the actual state of your security and guides you through the remediation process.
You'll immediately get a clear picture of your risks and concrete steps to fix them. This is an efficient way to start monitoring M365 security without heavy projects.
Measurement makes progress visible and helps justify investments.
Track these metrics on a monthly basis:
These metrics will tell you if your monitoring model is working and where there is room for improvement.
Monitoring your M365 environment is not a one-off project, but a permanent approach. Threats are evolving and your environment is changing daily. An effective monitoring model combines identity protection, automated alerts, clear remediation paths and staff skills.
Start with the basics: MFA for all, basic alerts in place and regular checks. Expand in stages as needed. Vahti provides SMEs with an easy way to see the true state of security in their M365 environment and remediate risks in a timely manner.
Security is not a barrier to business. It is a prerequisite for trust and growth.
Microsoft is responsible for the infrastructure and availability of the platform, but the customer is responsible for their own data, user accounts and settings. Monitoring exposes risks and changes that Microsoft does not automatically respond to.
Vahti helps you see the true state of security in your M365 environment at a glance and prioritizes risks for remediation.
You can deploy basic monitoring in a matter of hours. Enabling MFA, configuring basic alerts and connecting Vahti to the environment are quick steps.
Connecting Vahti to your M365 environment takes just a few minutes, and you'll get an instant view of your security posture.
The cost depends on the implementation chosen. M365's built-in alerts are included in the basic licenses. Vahti offers SMEs user-based pricing that scales with the size of the organization.
Vahti charges based on active M365 users, and does not include guests or shared mailboxes.
An audit provides a snapshot of the situation at a single point in time. Monitoring tracks the environment around the clock and detects changes and anomalies in real time.
Vahti monitors your M365 environment 24/7 and identifies risks before they become problems.
Not necessarily. Vahti is designed so that even without deep technical knowledge, you understand the risks and can take action to address them. The remediation instructions are written in plain language, and you can forward a remediation request to an expert if necessary.