Email systems are quickly moving to the cloud with more and more businesses choosing hosted platforms such as Microsoft Office 365 and Google Workspace. These platforms are popular for messaging, productivity, and collaboration. However, if cloud email security is vulnerable, businesses face significant risks. These risks include account takeovers, theft of sensitive data, and interruptions in operations due to cyber threats.
In our comprehensive guide on cloud email security, we detail essential security measures that are relevant for all the major cloud email platforms. IT teams in organizations should use these measures to safeguard email accounts, protect the data within these emails, and ensure that business operations continue smoothly. These steps are especially important considering the constant evolution of threats targeting email systems. By following the guidelines in this guide, businesses can better defend themselves against these ever-changing email-borne attacks, ensuring a more secure and reliable email environment.
Perform Simulated Phishing and Compromise Testing
Ethical phishing simulations provide invaluable visibility into an organization’s susceptibility to compromise. Skilled testers mimic tactics used by real-world adversaries such as:
- Spoofing display names and email addresses to impersonate trusted contacts
- Crafting urgent or alarming messages to trigger emotional responses
- Including malicious links and attachments that capture credentials or deploy payloads
Detailed post-assessment reports reveal potential control gaps and improvements based on phish prone percentages, response times and user habits. Testing also gauges effectiveness of security awareness training.
Testing should also attempt compromised account scenarios that access, extract or delete data, change configurations and spread threats internally after gaining access. These simulations evaluate incident response readiness.
Enforce Multi-Factor Authentication
- Initiating Multi-Factor Authentication (MFA): Implementing MFA for all email accounts is a proactive step towards enhancing security. This strategy significantly diminishes the risk of data breaches, even if an attacker compromises login credentials.
- Additional Verification Layer: MFA requires users to provide an extra verification step, typically from a separate device, during the sign-in process. This additional layer creates a robust barrier against unauthorized access attempts.
- Diverse Verification Methods:
- Approval Prompts: Users receive notifications on trusted devices, asking them to approve or deny access attempts.
- Authenticator Apps: These apps generate time-sensitive codes as a second factor for authentication.
- Security Keys: Physical devices, such as USB keys, serve as a hardware-based method to confirm user identities.
- Biometrics: Fingerprint or facial recognition adds a personal and non-replicable factor to the authentication process.
- Integration with Cloud Email Platforms: Most cloud-based email services offer built-in MFA options. These integrated solutions simplify the implementation and management of MFA across the organization.
- Standardization Across the Organization: Enforcing MFA uniformly, particularly for accounts with elevated privileges, is a vital security measure. It ensures that all users, regardless of their role, contribute to the overall security posture of the organization.
- Enhanced Protection for Privileged Accounts: Given their access to sensitive information, securing privileged accounts with MFA is crucial. It significantly reduces the likelihood of successful attacks targeting these high-value targets.
Maintain Least Privilege Access
- Overly permissive account privileges unnecessary for a user’s duties provide avoidable pathways for threats to propagate in the event of compromise. Best practices include:
- Auditing and pruning unnecessary mailbox permissions, delegation rights and folder/mailbox access.
- Restricting send-as and send-on-behalf privileges only to specific approved use cases.
- Reviewing administrator and service account privileges for opportunities to implement just-in-time elevated access.
- Disabling legacy email protocols like IMAP and POP3 that bypass MFA and retain copies.
- Scrutinizing and minimizing privileges aligns to zero trust principles for reducing blast radius of email account takeovers.
Continuously Monitor for Anomalies
Detecting threats requires proactively monitoring email activity for anomalies indicative of compromise like:
- Sudden spikes in sent emails or external recipients for specific accounts which may signal autonomously spreading malware.
- Logins or mailbox access at unusual hours outside user patterns and time zones.
- Email inbox rules and forwards set to leak data to external accounts.
- Connection attempts from suspicious locations based on a user’s typical activity.
Tools like Microsoft Cloud App Security and Google Chronicle provide robust monitoring, anomaly detection and threat intelligence tailored for cloud email platforms.
Isolate and Secure Service Accounts
Accounts for automated workloads like cloud syncs, backups and integrations pose outsized risks since they often have elevated privileges combined with weak security controls around credentials and access. Recommended measures include:
- Assigning service accounts custom administrative roles with minimum required privileges.
- Enforcing highly complex randomly generated service account passwords with frequent rotation.
- Requiring MFA for all service account access, whether human or from applications.
- Restricting external access and network-level isolation using VLANs where possible.
By reducing privileges and access to only essential needs, organizations limit the potential impact of service account compromise.
Maintain Secure Email Hygiene Practices
Cloud email introduces new avenues for threats, making user education around secure email usage imperative. Core focus areas should cover:
- Avoiding opening links and attachments in messages from unrecognized senders. Validate legitimacy offline.
- Watching for social engineering subject lines designed to trigger urgency, curiosity or concern.
- Reporting suspicious messages with phishing indicators like typos, threats and urgent requests.
- Ensuring sensitive data is only shared externally using platform-provided message encryption.
Ongoing education and testing helps turn employees into a strong human firewall against email threats.
Manage Vendor and Third Party Access
Partners, contractors and vendors with email access to internal distribution groups or shared mailboxes introduce risk. Core steps include:
- Restricting delegated external accounts to “send only” permissions with no visibility into other group conversations.
- Enforcing secure temporary credentials that frequently rotate for any third-party shared mailboxes rather than permanent access.
- Confirming external accounts maintain multi-factor authentication and strong password policies.
Proactive third-party email access governance reduces exposure to outside organizations and prevents incidents from spreading internally if accounts are compromised.
Deploy Additional Message Security Layers
While cloud email platforms provide base security, layered controls boost protection:
- Implement secure email gateways (SEGs) inspecting all incoming messages for malware, phishing URLs/attachments and impersonation tactics.
- Configure DNS-based authentication like DMARC and DKIM to block spoofed emails pretending to be from your domains.
- Enable email encryption capabilities to secure sensitive communications end-to-end with standards like S/MIME, TLS and password-protected messages.
- Route emails through third-party threat intelligence services that identify emerging phishing sender patterns.
Multilayered defenses fortify protections and threat awareness.
Enforce Data Retention and Recovery
While cloud platforms provide high availability, organizations must take responsibility for email compliance retention and recovery readiness through:
- Enabling immutable data retention policies that meet legal and regulatory obligations for availability of historical messages and records.
- Implementing third-party email archiving to retain emails beyond what cloud providers may persist.
- Establishing data recovery procedures encompassing testing and maintaining backups of critical cloud email.
Proper retention and recovery avoids business disruption and non-compliance fines in the event of outages, data destruction attacks or accidental deletions.
Adopt a Zero Trust Approach
Applying zero trust principles enhances cloud email security by:
- Enforcing least privilege permissions so compromised accounts have reduced blast radius.
- Encrypting sensitive emails end-to-end so content remains protected if accounts are breached.
- Authenticating and authorizing all user sessions rather than trusting credentials and logins implicitly.
- Monitoring account usage for anomalies and risk factors like suspicious location to prompt additional verification.
While challenging to implement fully, zero trust philosophies plug trust gaps attackers take advantage of to propagate within cloud email after gaining initial access.
Maintain Email Security Posture Assessments
Given continuously evolving threats, maintaining visibility into cloud email risks through recurring posture assessments is imperative:
- Penetration testing simulates phishing, compromise and data exfiltration scenarios based on real-world tactics to quantify exposure.
- Configuration analyses identify common security missteps like open relays or legacy protocol usage.
- Reviewing user and administrator policies determines whether they adhere to least privilege and separation of duties best practices.
- Incident response evaluations assess detection, containment and remediation processes specific to email compromises.
Ongoing objective testing demonstrates email platform security efficacy and staff preparedness.
Conclusion
As more and more organizations move their email systems to the cloud, they face new kinds of risks and challenges. These challenges are unique because cloud environments work differently from traditional systems. They need special focus to make sure they are secure. Our guidelines offer a complete plan that is specially made for cloud email settings. This plan helps in managing risks, keeping data safe, and making sure that emails are always available, even as threats keep getting more sophisticated and harder to deal with.
If you want advice on improving cloud email security in a way that fits your business, please get in touch with our experts. When you plan ahead, use multiple layers of protection, and regularly test your systems, cloud email can be a safe way for your team to work together and communicate. By being proactive and cautious, you can use cloud email effectively without compromising on security.
