Closing Microsoft 365 SaaS security gaps

Microsoft 365 is one of the most widely adopted productivity suites. Over 3.7 million businesses worldwide rely on Microsoft 365 for communication, collaboration and productivity. However, its popularity has also made it a prime target for cybercriminals.

Threat actors are exploiting trusted Microsoft domains and misconfigured tenants to launch sophisticated business email compromise (BEC) campaigns. These attacks are orchestrated to steal user credentials to execute account takeover (ATO) attacks.

Even businesses with MFA enabled and endpoint security in place often find themselves blindsided by M365 ATO attacks. While Microsoft’s native controls and modern endpoint security solutions are formidable, they don’t see everything.

The reality is that the biggest blind spots aren’t on the device — they’re in the SaaS layer where attackers live once they’ve bypassed MFA. Once inside your Microsoft 365 environment, they can exfiltrate data, set up persistence and impersonate legitimate accounts without triggering device-based alarms.

That’s where cloud detection and response (CDR) comes in. In this article, we’ll take a look at some critical security gaps in Microsoft 365 and how CDR fills these visibility gaps and strengthens Microsoft 365 security.

Defining the Microsoft 365 SaaS security gap

Between what Microsoft 365’s built-in tools protect and the full scope of SaaS-based threats lies a critical blind spot that attackers aim to exploit.

Some examples include:

• OAuth abuse through malicious third-party apps grants attackers persistent backdoor access.
• Unmonitored guest accounts with excessive privileges quietly expand the attack surface over time.
• Orphaned external file links continue granting access to sensitive data months or even years after their purpose has expired.
• Token hijacking and Adversary-in-the-Middle (AiTM) techniques, which can bypass MFA entirely.

These threats don’t live on the endpoint; they live inside the SaaS layer itself, undetected for weeks or even months. Once adversaries have access to your M365 accounts, it’s very hard to detect them with the native tools. According to the Cost of a Data Breach Report 2024, businesses took an average of 292 days to detect credential-based breaches.

Without complete visibility and control, businesses risk leaving their Microsoft 365 environment wide open to an array of threats and security challenges.

Why traditional tools miss these threats

There has been a lot of investment in cybersecurity, but much of it is concentrated at the endpoint through EDR and AV or at the network level through firewalls. EDR and AV solutions are designed to protect the device, and their visibility ends there. Once an attacker gains access to your Microsoft 365 accounts via the cloud, EDRs and AVs won’t detect those threats.

Also, while Microsoft Secure Score is a valuable security benchmark, without continuous monitoring and action, it becomes reactive rather than preventative. And scaling it across multiple tenants can be complex and time-consuming.

Limited automation in Microsoft’s native alerts adds another challenge. They often require manual investigation and remediation, which delays response times.

Cloud detection and response explained

Cloud detection and response is a security approach that continuously monitors activities for suspicious behaviors, risky logins and abnormal data movements in cloud applications and services, such as Microsoft 365, Google Workspace and Salesforce.

The core capabilities of CDR include:

• Detecting MFA gaps, OAuth abuse and account misuse in real time.
• Stopping threats in their tracks through alerts or automated remediation.
• Monitoring SaaS configurations and catching changes that weaken security.

In SaaS platforms like Microsoft 365, much of the activity happens in the cloud, beyond the reach of traditional security solutions, such as EDR, AV or firewalls. CDR operates where the threats actually occur — in the cloud, inside user accounts.

Think of CDR as EDR for your cloud and SaaS applications. If you rely only on email security, you’ll stop many threats, but the most advanced and damaging ones will slip through. CDR closes that gap, just as EDR does for endpoints.

Close the gap in Microsoft 365 with SaaS Alerts

SaaS Alerts gives you complete visibility into your SaaS environments that native tools don’t provide. It continuously monitors account activity, guest accounts and file sharing to identify and detect threats early. Our industry-leading SaaS security solution provides real-time alerts on anomalous sign-ins, geolocation risks and privilege escalations so that you can stop threats in their tracks.

SaaS Alerts’ Fortify module effortlessly improves your organization’s Microsoft Secure Score. The automated security policy system for Microsoft 365 allows you to apply security recommendations across all your tenants in minutes. It offers predefined policy templates aligned with Microsoft’s best practices to improve secure scores quickly and efficiently. On average, our partners using Fortify have improved their secure scores by 35.98%.

Our cloud detection and response platform automatically remediates SaaS threats. It leverages machine learning to lock affected accounts, expire tokens and block risk logins within minutes. SaaS Alerts’ automatic detection and shutdown capabilities remove unused guest accounts and revoke unsafe SaaS-to-SaaS integrations to protect your business-critical apps from internal and external threats.

Proof in the numbers: How SaaS Alerts strengthens Microsoft 365 security

In 2024, SaaS Alerts detected over 61 million critical alerts across SaaS environments. While external threats triggered some of the alerts, others were caused by internal mistakes or oversight, such as orphaned file-sharing links, forgotten guest user accounts and a lack of MFA enforcement.

Our CDR platform automatically blocked 11,478 threats, preventing costly breaches and giving our partners complete peace of mind. In the process, we helped them avoid up to $1 million in potential losses per business each year.

In one real-world case, a partner detected and stopped 15 account compromises within the first month of using our solution.

Get your FREE copy of the 2025 SASI Report for insights on the latest SaaS security trends.

The bigger picture: From gap to advantage

Closing SaaS security gaps isn’t just about avoiding breaches — it’s also about building trust, meeting compliance obligations and reducing IT burnout with automation.

With SaaS threats constantly evolving, relying solely on endpoint protection or Microsoft’s native tools isn’t enough. You need a reliable CDR solution that offers visibility into the SaaS blind spots where attackers hide. The first step in closing the security gaps is knowing where they exist. That’s why we invite you to uncover the hidden risks in your Microsoft 365 environment with our Cyber Risk Assessment.

Get your FREE assessment today!