Office 365 Security Best Practices

Even before the COVID-19 pandemic, organizations were increasingly adopting Office 365 and similar Software as a Service (SaaS) solutions as part of digital transformation initiatives. The switch to remote work driven by COVID-19 only accelerated this transition.


As Office 365 becomes a more valuable and widely-used tool, it has also become one of the most exploited channels for cyberattacks. Securing this platform against cyber threats ranging from credential theft to malware delivery is essential for enterprise cybersecurity.

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The Top 7 Office 365 Security Best Practices

Office 365 is a valuable tool but also poses significant security risks. Implementing the following security best practices is vital to minimizing the cyber risk of Office 365.

#1. User Education

Office 365 is a common target for phishing attacks. These attacks leverage its email and document sharing capabilities to spread malicious links and malware within an organization. Employee cybersecurity awareness training is an essential component of an organization’s email security strategy.


Regularly training employees to recognize and respond appropriately to the latest phishing threats is essential.

#2. Enable MFA

Office 365 accounts are a leading target for credential stuffing and similar password guessing attacks. If an attacker gains access to an employee’s login credentials, these credentials can be used to access their email and other Office 365 apps to steal data or spread malware.


Multi-factor authentication (MFA) is available in Office 365 and makes it necessary to have access to a second authentication factor (in addition to a password) to log into an account. This limits the impact that a compromised password has on enterprise cyber risk.

#3. Block Corporate Password Reuse

Weak and reused passwords are a major gap in many organizations’ cybersecurity. Employees commonly use the same password for multiple personal and corporate accounts, increasing the risk that this password will be compromised in a data breach or guessed by an attacker.


When a new password is created or reset, it should be compared to those of other accounts and previous passwords to prevent password reuse. By doing so, an organization both limits the probability that an account will be compromised using credential stuffing and ensures that a single compromised password cannot be used to gain access to multiple Office 365 accounts.

#4. Deploy an Anti-Malware Solution

Ransomware and other malware are growing increasingly sophisticated and evasive. This makes it more difficult for legacy security solutions to detect and block it before damage is caused to an organization.


Office 365 provides a vector for malware to gain initial access to an organization and spread through its network environment. A targeted anti-malware solution is essential for blocking the spread of malware within an organization via Office 365.

#5. Deploy Anti-Phishing Defenses

Office 365 is a leading target of phishing attacks, including business email compromise (BEC) attacks. If an attacker gains access to one Office 365 account, they can leverage this access in spear phishing attacks to expand their foothold or achieve other objectives.


Deploying an email security solution with anti-phishing capabilities can help to minimize this risk in a number of ways. Malicious links and attachments can be detected by inspecting emails in a sandboxed environment. Artificial intelligence can be used for natural language processing (NLP) to identify suspicious language that points to an attack and to detect other warning signs of a phishing email.

#6. Implement Collaboration App Security

While email is the most famous mechanism for phishing and spreading malware, other collaboration applications can be used for this purpose as well. Office 365 offers a number of applications for online collaboration, including Microsoft Teams and OneDrive.


These applications have all of the same phishing risks as email. Malware and malicious links can be dropped in chat windows within Teams or embedded in shared documents and folders on OneDrive. Office 365 security requires a security solution that protects not just email but also collaboration apps.

#7. Deploy a Mobile Security Solution

In response to the COVID-19 pandemic, employees are increasingly working remotely. This has accelerated an existing trend toward adoption of mobile devices and bring your own device (BYOD) policies in the workplace.


Mobile devices have unique security requirements and require security solutions designed specifically for them. Deploying mobile security solutions is essential to ensuring that a compromised mobile device cannot use Office 365 mobile apps to provide an attacker with access to an organization’s sensitive data and systems.

Securing an Office 365 Deployment

Office 365 provides a number of benefits to an organization. Its support for user-friendly online collaborations is more important than ever in the wake of COVID-19, when businesses are considering more permanent support for remote work.


However, as organizations grow more reliant on Office 365, it becomes a more valuable target for cybercriminals as well. Implementing these best practices is essential to ensuring that this valuable tool does not create security gaps that an attacker can exploit.


Check Point’s Harmony Email & Office provides security designed specifically for Office 365 and collaboration apps. To see how Harmony can improve Office 365 for yourself, you’re welcome to request a demo today.

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