Microsoft 365 Ransomware Protection Guide

Why Microsoft 365 is a Ransomware Target

According to the 2023 ThreatLabz State of Ransomware Report, the average enterprise ransom payment was in excess of $100,000, making it a lucrative method for cybercriminals to make money. However, it’s not just financial incentives and widespread adoption of M365 that makes it a prime target. Below are some additional reasons why Microsoft 365 is prone to ransomware attacks:

• Complexity of the environment: Microsoft 365’s diverse range of services can make it difficult for IT departments to monitor and detect security threats.
• High-value data: Microsoft 365 stores large amounts of valuable data, making it an attractive target for cybercriminals looking to exploit and encrypt sensitive information.
• Lack of awareness: Users may not be aware of security features and best practices associated with Microsoft 365, making it easier for ransomware to infect systems.
• Integrated services: Microsoft 365’s integrated services can provide a wide range of attack vectors and entry points for adversaries to exploit.
• Zero-day vulnerabilities: Microsoft 365 is not immune to zero-day vulnerabilities, which can be exploited by attackers, potentially allowing them to bypass security controls and launch a successful ransomware attack.

How Microsoft 365 Ransomware Attacks works

Below are the key steps involved in a Office 365 ransomware attack:

1. Initial Attack – Ransomware targets Microsoft 365 services, including OneDrive, SharePoint, and Outlook, to infect files and data. Initial entry could be the result of phishing attacks, RDP attacks, insider attacks, and more.
2. Rapid Encryption – The ransomware encryption is highly robust and very difficult to decrypt without the unique key held by the attacker. This encryption process can be swift, taking only minutes to encrypt hundreds or thousands of files.
3. Ransom Demand – The ransomware demands payment, typically in cryptocurrency, in exchange for the decryption key. The ransom demand varies widely, from hundreds to thousands of dollars for individuals to millions of dollars for organizations.
4. Data Exfiltration (Optional) – Some ransomware variants have the capability to exfiltrate sensitive data before encrypting it, putting the targeted organization’s sensitive information at risk.
5. Evasion Techniques – Modern ransomware variants use advanced techniques to evade detection by traditional antivirus solutions, making it difficult to detect and prevent the attack.
6. Payment and Recovery (Not Recommended) – Paying the ransom does not guarantee the retrieval of files and may even incentivize further attacks. It is generally discouraged to pay the ransom, as it does not provide a guarantee of success and may lead to further exploitation.

Common Attack Vectors

To fortify your Microsoft 365 environment, it’s essential to understand the common attack vectors and entry points that ransomware uses to compromise your system. Some of these attack vectors include:

Phishing and social engineering – Phishing emails and social engineering attacks are two common tactics used to trick victims into revealing sensitive information. Phishing emails pose as legitimate sources, often containing malicious links or attachments that can lead to malware infections. Social engineering attacks, on the other hand, exploit human psychology and behavior, convincing users to divulge sensitive information or install malware by pretending to be a legitimate source, such as an IT support team.

Remote Desktop Protocol (RDP) attacks – RDP attacks occur when an attacker gains access to a Microsoft 365 system by exploiting vulnerabilities in RDP, a protocol used to connect to remote computers. This allows the attacker to access the protected system and potentially install ransomware.

Insider threats – Insider threats occur when an authorized Microsoft 365 user, such as an employee, intentionally or unintentionally compromises the security of the system, potentially by installing malware or giving away login credentials to attackers.

Credential stuffing – Credential stuffing is an automated attack where an attacker uses a software program to rapidly attempt to log in to multiple email accounts using a combination of usernames and passwords obtained from previous data breaches or other sources. This can help the attacker gain access to Microsoft 365 accounts.

Exploit kits – Exploit kits are software packages that contain pre-built exploits for known vulnerabilities in software applications, operating systems, or other technologies. These exploits can be used to gain unauthorized access to Microsoft 365 systems and data.

Drive-By downloads – Drive-By downloads occur when a user visits a compromised website or clicks on a malicious link, which then downloads and installs malware, including ransomware, without the user’s knowledge or consent.

Native Microsoft 365 Options for Ransomware Protection

Below are some of the most notable ways to detect, prevent and recover from a ransomware attack within your Microsoft 365 environment:

Ransomware Detection and Prevention:

• Assess security configuration with Microsoft Secure Score
• Configure Exchange email settings to industry-standard security configuration
• Require Multi-Factor Authentication (MFA)
• Label sensitive data with Microsoft Information Protection
• Regularly scan devices with Windows Defender or Microsoft Security Essentials
• Disable Exchange ActiveSync and OneDrive sync if ransomware attack suspected
• Use Microsoft Defender for Identity and Endpoint to detect compromised identities and devices

Ransomware Recovery:

• Use Office 365 retention/archival policies to recover data
• Use OneDrive versioning, Recycle Bin, and/or Preservation Hold library to recover files
• Restore OneDrive to a previous point in time within the last 30 days
• Use advanced protection features like sandboxing in Microsoft Advanced Threat Protection or Microsoft Defender for Office 365 (This is optional and only available in premium plans)

Limitations of Native Microsoft 365 Options for Ransomware Protection

While Microsoft 365 provides various security controls and capabilities to help safeguard data and applications, it is ultimately the organization’s responsibility to ensure the proper protection of their data and identities. Unfortunately, the native ransomware recovery tools available through Microsoft 365 have limitations, such as being able to only restore data for up to 90 days. Furthermore, data deleted by users or administrators can be irretrievable from Office 365 applications, adding an additional layer of complexity to data management. Finally, storage costs for retention can become substantial, exceeding the 11TB limit of Microsoft 365, and relying on retention policies as a backup solution for a period of three years can be a costly endeavor.

How Lepide Helps

To safeguard against ransomware attacks, it’s essential to identify and remediate vulnerabilities in your organization’s overall security posture.

The Lepide Data Security Platform leverages machine learning-powered behavioral analytics to learn the typical behavior of your Microsoft 365 users, enabling it to detect anomalies and alert you to potential threats.

This proactive approach involves monitoring for early signs of a ransomware attack, including threshold alerting and pre-built threat models. Custom scripts can be used to swiftly quarantine a potential ransomware attack, which might include disabling compromised accounts, adjusting firewall settings, or shutting down affected servers. Additionally, the platform provides over 400 pre-built reports to provide real-time visibility into changes made to your M365 infrastructure, allowing you to stay ahead of potential risks and take swift action to protect your organization.

If you’d like to see how the Lepide Data Security Platform can help to protect your Microsoft 365 from ransomware attacks, schedule a demo with one of our engineers.