Countermeasures for Outbound Email Threats

By Emma Taylor

Summary

In today's digitally driven environment, email communication serves as the backbone for rapid information exchange and streamlined decision-making processes. However, this convenience is not without its risks, particularly when it comes to outbound emails. The potential for sensitive information leakage and the looming threat of account extortion through email create significant challenges. These incidents not only jeopardize data security but also expose organizations to severe reputational and financial risks. Effectively addressing these challenges demands a holistic strategy that combines robust technical solutions, well-defined policies, and vigilant oversight. This multifaceted approach is crucial for mitigating the diverse and evolving threats associated with outbound emails. In the forthcoming sections, we will delve into the intricacies of combating sensitive outbound email threats.

Countermeasures for Outbound Email Threats by Users

- Secure Email

A more secure alternative to traditional email transmission involves sending a secure email containing a link that grants access to a secure web portal for previewing email information. In this approach, recipients access the email content through the provided link, ensuring an additional layer of security by not directly transmitting sensitive information through the email itself. It's crucial for users to have the capability to manage these securely transmitted emails, providing control and oversight over the secure communication process.

- Approval Email

The approval email system enables users to configure an authentication program that empowers approvers to send notifications when there are pending authentication permission requests. When specific keywords and attachments are present in the email, the approver can initiate an approval process. These emails may be sent when the approver allows or rejects the transmission of an email with specific criteria, such as a particular title, attachment, or keyword that necessitates approval based on the file extension. Approval may be required for any combination of the email’s title, attachment, or file extension.

- Email Delivery Restriction

Implementing limitations on the number of emails sent simultaneously is a viable strategy. This approach maintains the stability of the email server and enhances account security by imposing restrictions on both the total number of emails sent per day and the number of receipts permitted per individual email.

● Countermeasures for Intentional Information Leakage

The outbound email blocking policy is established to enhance security by preventing the unauthorized leakage of information and data through emails. Conditions outbound in this policy include limitations on large attachments, restrictions on image sizes within the email body, creating an exception sender list for specific targets, and monitoring for personal information or specific attachments in file names and extensions.

Additionally, the policy enables the implementation of a delayed sending and retrieval mechanism for outbound emails. Users can set a slight delay before an email is sent, and during this delay, they have the option to cancel the email transmission. It’s important to note that once an email is retrieved during this delay, it cannot be recovered again, necessitating the rewriting of the email if cancellation is desired.

● Countermeasures for Unintentional Information Leakage

Email encryption serves as a protective measure by encrypting or disguising the contents of emails and attachments, ensuring that sensitive information remains confidential and is accessible only to authorized recipients. This approach not only prevents unauthorized parties from intercepting sensitive data but also aids in compliance with data protection regulations, reinforcing the confidentiality of communicated information.

In conjunction with email encryption, specific conditions for email conversion are established. These conditions ensure the secure transmission of large attachments from an isolated internal network to an external one, allowing them to be categorized as general attachments. Additionally, the functionally of delivering converted emails after obtaining approval is activated, adding an extra layer of security to the process.

Under the email recovery condition, a thorough security review of large attachments is conducted. this review follows a predefined email transfer policy to classify attachments as general attachments, enabling the safe transmission of large attachments from the isolated internal network to the external network. Furthermore, encrypted external network path information for large attachments is attached as a URL, enhancing the security measures implemented during the transfer process.

Countermeasures for External Outbound Email Attacks

● Countermeasures for Attacks Using Account Take-over

A pivotal strategy in bolstering security is the implementation of IP privilege settings, affording the security administrator the ability to tailor the system to permit communication exclusively from pre-approved IP addresses and emails originating from specific countries. This proactive measure acts as a robust filter, effectively screening out potentially harmful emails that could emanate from unreliable or high-risk sources. By restricting communication pathways to only approved entities, this approach significantly diminishes the risk of account takeover attacks. By curbing the avenues through which attackers could potentially gain unauthorized access to an email account, the organization can enhance its overall security posture and fortify defenses against potential cyber threats.

● Countermeasures for Unauthorized Mail Server Access

The email server and IP access control mechanisms empower the security administrator to exercise precise control over the secure email link transmission by imposing restrictions on mail access or mail client interactions. Through the registered IP address, the transmission of emails can be blocked, and control over mail client communication is achieved by regulating communication access based on the client server protocol. Specifically, emails are permitted to transmit exclusively within registered IP addresses and designated countries. Comprehensive logs detailing email server access restrictions, including information such as IP addresses and dates, are maintained, providing transparency and accountability in the management of email communications.

In the face of a constantly evolving cyber threat landscape and the ever-present possibility of human error, safeguarding outgoing email is not an option but a must. To effectively prevent and mitigate these risks, it is advisable to implement robust email security measures, establish data protection policies aligned with security best practices, and use technology solutions that adhere to international standards, including encryption and advanced threat detection. Continuous inspection and monitoring, facilitated by technology in compliance with international standards, play a critical role in identifying and resolving issues related to outgoing email. Regular oversight of outgoing email security not only helps in its regulation but also ensures compliance with Mail Inspector standards, preventing inadvertent sharing of critical information. In essence, the incorporation of security standard technologies, encompassing technical security solutions and a comprehensive Mail Inspector, backed by continuous monitoring, is indispensable. This holistic approach not only effectively addresses outbound email threats but also ensures a robust security posture, fortifying the organization against potential vulnerabilities and ensuring a secure digital environment.

References

Outbound Email Security (powerdmarc.com)

https://ironscales.com/glossary/outbound-email-protection

:https://www.leapxpert.com/data-leakage-the-risk-the-reality-and-messaging-channels/

<ITU-T X.1236 Security requirements and countermeasures for targeted email attacks>

https://www.itu.int/ITU-T/recommendations/rec.aspx?rec=15710&lang=en