The Microsoft 365 (M365) Ransomware detection identifies behaviors indicative of ransomware activity within an M365 environment. Ransomware is a type of malware that encrypts files or data and demands payment for their release. While traditional ransomware attacks target endpoint devices and servers, modern attackers increasingly exploit cloud services like M365 to disrupt operations, encrypt cloud-hosted files, and extort organizations. This detection helps security teams identify and mitigate potential ransomware threats before they cause significant damage.
Attackers target M365 environments with ransomware to disrupt business operations, exfiltrate sensitive data, and demand ransom payments. Cloud-based ransomware attacks often originate from compromised user accounts, exploited OAuth applications, or adversaries leveraging automation tools to encrypt files stored in SharePoint and OneDrive. Since M365 is widely used for collaboration, a successful ransomware attack can impact multiple users, leading to significant data loss and operational downtime.
Legitimate users may trigger similar behavior during bulk file migrations, large-scale document updates, or scripted data management tasks. IT administrators, for example, might move or modify large numbers of files when restructuring a SharePoint site or performing backups. Understanding the context of these changes—such as whether they were planned, who initiated them, and if they align with normal business activities—is essential for distinguishing between benign and malicious actions.
An employee receives an email that appears to be from Microsoft, prompting them to approve an OAuth request. Unknowingly, they grant permissions to a malicious application, which immediately begins encrypting files across their OneDrive. The M365 Ransomware detection triggers an alert due to rapid file modifications, prompting an investigation that identifies the compromised account and stops further damage.
An IT administrator is migrating large amounts of SharePoint data to a new site, causing a surge in file modifications. The detection is triggered, but upon review, the security team confirms it as a planned migration, avoiding unnecessary incident response actions.
If this detection indicates a genuine threat, the organization faces significant risks:
Ransomware can encrypt critical business files, making them inaccessible and severely impacting daily operations.
Paying a ransom does not guarantee data recovery, and public disclosure of a ransomware incident can harm an organization's reputation.
Data breaches and loss of access to sensitive information may lead to violations of compliance requirements, resulting in legal and financial penalties.
Identify the user or account associated with the suspicious file modifications and check for any unauthorized access or anomalies in their login behavior.
Determine if the changes involve encryption, renaming, or mass deletions that resemble ransomware activity, and compare against normal business operations.
Investigate if other security tools (such as Microsoft Defender or SIEM alerts) report concurrent suspicious activities, such as brute-force login attempts or abnormal OAuth permissions.
If ransomware activity is confirmed, isolate the compromised account, revoke access tokens, and restore affected files from backups. Notify incident response teams to take further action.
Vectra AI uses behavioral analytics to identify unusual file modifications that match ransomware activity, distinguishing them from normal user actions.
Validate the user’s intent, check for known business activities that may cause similar behavior, and fine-tune detection policies if necessary.
Attackers may gain access through credential theft, phishing, or malicious OAuth applications to encrypt or delete cloud-stored files.
Immediately isolate affected accounts, revoke access tokens, restore files from backups, and conduct a forensic investigation to identify the root cause.
Unlike endpoint solutions, this detection focuses on cloud-based ransomware behaviors, such as abnormal file changes in M365 rather than malware running on a device.
While it effectively detects ransomware behaviors, novel ransomware variants with unique attack methods may require additional investigation.
Yes, Vectra AI provides real-time monitoring and alerting, enabling rapid response to potential ransomware threats.
While Vectra AI focuses on detection, it helps security teams respond quickly to minimize damage and prevent further spread.
Yes, it applies to all organizations using M365 services, including OneDrive and SharePoint.
While advanced attackers may attempt to evade detection, Vectra AI's Attack Signal Intelligence continuously monitors and correlates with other security events to identify and mitigate threats effectively.