Top Microsoft 365 Security Concerns & How To Overcome Them

With over 250 million monthly users, Microsoft 365 is one of the most widely used cloud suites. But this immense popularity makes Microsoft 365 an appealing target for cybercrime, along with the valuable data that is stored within Microsoft 365 environments.

In 2022, one in five organizations experienced at least one account compromise in Microsoft 365. As Microsoft 365 environments continue to be targeted, it’s important to be aware of common Microsoft 365 security concerns as well as measures you can take to protect your organization. This article will discuss the key Microsoft 365 security challenges, the three layers of their security strategy, and how you can keep your company safe from damaging, costly attacks in Microsoft 365. 

Top Microsoft 365 Email Security Concerns

To protect your organization against the ongoing threat of cyberattacks on Microsoft 365 environments, you have to be well-informed about common security risks. Below are five frequently occurring Microsoft 365 security concerns that you should be aware of.

Privilege Escalation Resulting in Further Malicious Activities 

Privilege escalation is a type of attack where a malicious actor gains privileges on a system or application they shouldn’t have access to. To prevent privilege escalation:

  • Implement role-based access control to restrict access to sensitive systems and applications.
  • Regularly update and patch systems to mitigate known vulnerabilities that attackers can exploit.
  • Use multi-factor authentication (MFA) to protect privileged accounts from unauthorized access.
  • Monitor and log all privileged access attempts to detect suspicious activities.

Bypassing Multi-factor Authentication Leading to Unauthorized Access 

Multi-factor authentication (MFA) is an effective security measure to prevent unauthorized access. However, attackers can still bypass MFA through various methods. To prevent bypassing MFA:

  • Use advanced MFA techniques such as biometrics, behavioral analytics, and geolocation-based authentication.
  • Limit the number of authentication attempts to prevent brute force attacks.
  • Use an out-of-band channel for MFA such as SMS or email to prevent SIM swapping attacks.
  • Educate employees about the risks of phishing attacks and to never share MFA credentials with anyone.

Phishing Attacks Putting Sensitive Data at Risk

spear phishing statPhishing attacks are one of the most common methods used by attackers to steal sensitive information. A recent report states that roughly 20% of all phishing emails found were marked as clean by the Microsoft 365 Exchange Online Protection (EOP) and reached users' inboxes. To prevent phishing attacks:

  • Educate employees about how to identify phishing emails and avoid clicking on suspicious links or attachments.
  • Implement email security measures such as spam filters, anti-virus, and anti-malware software.
  • Use web filtering to block access to known malicious websites.
  • Conduct regular phishing simulations to train employees on how to respond to phishing attacks.

Malicious Macros Threatening Critical Systems 

Malicious macros are a type of malware that uses macros embedded in documents to execute malicious code. To prevent malicious macros:

  • Disable macros in documents by default and only enable them on a case-by-case basis.
  • Implement file blocking to prevent the execution of files that contain malicious macros.
  • Use anti-malware software to detect and remove malicious macros.
  • Educate employees on the risks of opening suspicious documents and how to report them to IT.

Data Exfiltration Leading to the Compromise of Sensitive Information

Data exfiltration is the unauthorized transfer of data from a system or network to an external location. To prevent data exfiltration:

  • Implement data loss prevention (DLP) solutions to monitor and block unauthorized data transfers.
  • Implement encryption to protect sensitive data from being accessed by unauthorized users.
  • Use firewalls and intrusion detection/prevention systems (IDS/IPS) to detect and block suspicious network traffic.
  • Educate employees about the importance of data security and the risks of data exfiltration.

Why Threat Actors Target Microsoft 365

cybersecurity microsoft 365Cybercriminals are targeting Microsoft 365 environments to steal sensitive information using increasingly complex and sophisticated tools. They are even using Microsoft capabilities, such as Static Web Apps, to create false landing pages that contain the Single Sign-On (SSO) option to harvest Outlook, Microsoft 365, and other credentials. Attack vectors can be found in Microsoft Office Online, Outlook, OneDrive, Sharepoint, Microsoft Teams, and third-party cloud providers. Clients are responsible for their own network security under shared protection models. The threat level has increased as ransomware and phishing attacks have become cheaper and easier to facilitate, with ransomware kits being sold on the dark web. Attackers target Microsoft 365 for several reasons, including:

  • High profitability: Depending on the target, attacking Microsoft 365 can be highly lucrative for cybercriminals, as sensitive data and information stored within the platform can be valuable on the black market.
  • Widespread use: More and more businesses are migrating their essential data and functions to Microsoft 365, making it a prime target for attackers. Its integration and ease of use have reduced friction and streamlined services and communication, making it an attractive option for organizations.
  • Third-party cloud applications: The use of third-party cloud applications within Microsoft 365 provides additional attack angles that may be difficult to spot and secure, increasing the risk of a successful attack.
  • Lack of multi-factor authentication: Certain users may not have embraced multi-factor authentication, which can make it easier for attackers to gain unauthorized access. Users without multi-factor authentication are attacked 10 times more often than those who use it, making it a significant risk factor.
  • Machine learning: Machine learning algorithms are now being used by attackers to download data en masse and sift through it as their compromised access continues. This allows attackers to steal large amounts of data more efficiently and potentially remain undetected for longer periods.

Microsoft 365 Vulnerabilities

Microsoft 365 is a popular productivity suite used by many organizations around the world. While Microsoft provides several security mechanisms to protect Microsoft 365 assets from malicious software, it's still important to be aware of vulnerabilities that could potentially lead to security breaches. 

Recently, Microsoft has made significant investments in improving its threat and vulnerability management experiences in Microsoft 365. As part of this effort, they have combined existing product experiences and functionalities to enhance security capabilities that protect, detect, investigate, and respond to email, collaboration, identity, and endpoint threats.

Despite these efforts, vulnerabilities can still exist in Microsoft 365. For instance, in 2021, researchers found a vulnerability in Microsoft Teams that could have allowed hackers to gain access to sensitive data, including conversations and files, from Teams accounts. The vulnerability had been present for more than a year before it was discovered and patched by Microsoft. 

Another example of a vulnerability in Microsoft 365 that was exploited for more than a year is the "ZeroLogon" vulnerability, discovered in August 2020. This vulnerability allowed attackers to gain control of a domain controller and ultimately take over an entire network. Microsoft released a patch for the vulnerability in August 2020, but many organizations were slow to apply the patch, leading to a number of successful attacks.

To protect against these and other vulnerabilities, organizations should stay up to date on the latest security patches and ensure that they are promptly applied to all Microsoft 365 assets.

The Three Layers of Microsoft’s Email Security Strategy

Microsoft's security strategy is based on a three-layer approach that includes prevention, detection, and response to cyber threats.


Microsoft implements various measures to prevent attacks, such as encryption, access controls, and regular security updates to its products. They also leverage Machine Learning and Artificial Intelligence to identify and block threats in real-time.


Microsoft uses various tools to detect threats, including real-time monitoring, behavioral analytics, and threat intelligence. They also conduct regular security assessments to identify vulnerabilities and improve their security posture.


In the event of a security breach, Microsoft has a team of experts dedicated to incident response. They follow a well-defined incident response plan that includes containing the breach, assessing the damage, and implementing remediation measures.

Both External & Internal Threats Are a Serious Concern for Microsoft 365 Users

Cloud computing information technology concept, data processing and storage platform connected to internet network, specialist engineering systemWhile external threats pose a significant risk, internal threats are also among the top security concerns in Microsoft 365. Unauthorized file sharing and privilege abuse are some of the major problems that can occur. Although the platform has features to safeguard data from unauthorized access, granting permissions too easily can result in serious issues.

Sharing files with others requires trust that they will handle the data appropriately. Even if the sender takes all necessary precautions, an irresponsible recipient leaving their account open on a public device can put the sender's account at risk.

To mitigate these risks, it's crucial to limit access to files and ensure that recipients understand the importance of Internet safety. Organizations should establish strict access controls and provide regular security training to their employees to avoid the risks of internal security breaches.

Top Microsoft 365 & Cloud Email Protection Tips 

​​The Microsoft Secure Score

Microsoft Secure Score is a measurement of an organization's security posture, with a higher number indicating more recommended actions taken, and provides a list of recommended actions that you can take to improve the security of your organization. Recently, it has been updated to support security defaults in Azure Active Directory, which makes it easier to help protect your organization with pre-configured security settings for common attacks. If you turn on security defaults, you'll be awarded full points for the recommended actions.

Enable Multi-Factor Authentication

Multi-Factor Authentication (MFA) adds an extra layer of security to your organization by requiring users to provide additional authentication factors beyond their password to access their accounts. Enabling MFA for all users and login methods with Azure AD Security Defaults is recommended. This option enables you to easily and quickly enforce MFA for all users in your environment with a stringent policy to challenge administrative accounts and administrative logon mechanisms.

Discover and Classify Critical Assets

Knowing what your critical assets are is essential in protecting them. Microsoft recommends discovering and classifying your critical assets. Once you've identified them, you can prioritize protecting them from potential threats.

Enforce Least Privilege Access

Enforcing “least privilege” access means giving users only the access they need to perform their jobs and nothing more. This helps reduce the risk of a data breach or other security incident. Microsoft recommends enforcing “least privilege” access.

Enable Unified Audit Logging

Unified Audit Logging provides a centralized view of all user and administrator activity in your environment. It helps you detect and investigate potential security incidents. Microsoft recommends enabling Unified Audit Logging.

U.S. Government Agencies Impersonated in Microsoft 365 Phishing Attacks

A persistent phishing campaign aimed at U.S. government contractors has expanded its tactics to employ higher-quality lures and more sophisticated documents. The campaign uses phishing emails that entice recipients with requests for bids on lucrative government projects, redirecting them to phishing pages designed to appear as legitimate federal agency portals.m365 headline

Initially targeting the U.S. Department of Labor, the threat actors have now expanded their focus to include the Department of Transportation and the Department of Commerce. The campaign has undergone careful revisions, including consistent formatting and larger logos in phishing emails, simplified and smaller PDF files with prominent logos and department-specific metadata, improved phishing web page behavior with HTTPS encryption, and the addition of a Captcha Challenge step on the phishing page. 

The threat actors have also adopted long domain names to appear legitimate, particularly on mobile browsers. With the campaign continuously evolving and closely mimicking genuine bid requests and state bidding portals, it becomes challenging to detect signs of fraud. To defend against these attacks, recipients should scrutinize details such as the sending address, landing URL, and consider accessing bidding portals through search engines rather than provided links.

Keep Learning About Microsoft 365 Vulnerabilities

Despite the security concerns, many have decided the advantages of Microsoft 365 outweigh the risks. It is essential that organizations take a comprehensive approach to mitigate critical vulnerabilities in their Microsoft 365 environment. Consistent evaluation and maintenance are necessary to achieve a strong security posture. By implementing the strategies and tools shared in this article, organizations can better protect their Microsoft 365 environment from potential security threats. 

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