Layered schemes are used in most information security strategies, and it is essential to establish a similar approach to protecting the organization from unwanted email. In fact, spam and phishing are some of the biggest problems IT security managers face today. According to LinkedIn’s “2017 Cybersecurity Trends Report,” phishing attacks are a top concern for 37 percent of security professionals surveyed, ahead of insider threats (33 percent) and malware (32 percent).

A Layered Approach to Email Security

To protect corporate data from spam and phishing attacks, companies need basic, layered protection for their email services, whether hosted locally or in the cloud. Let’s take a closer look at this approach to illustrate how each layer compliments the organization’s overall data protection strategy.

Layer 0 or 6: SIEM, Spam Control and Monitoring

This protection layer can be either the initial or the final step, depending on how you look at it. To start, we should generate data about quantities of emails cataloged as spam. From this data, we can extract a statistic that allows us to make a business case for the investment or the process to improve our current antispam protection system.

However, the process of spam control through security information and event management (SIEM) could also be the sixth and final layer of protection, because it allows us to generate the statistics necessary to determine the number of attacks that were stopped by the other layers of protection and thus validate the effectiveness of our layered strategy.

Layer 1: Mail Scanning Via External Services

To begin with this layer, we have to consider that many default antispam protection systems lack the latest threat detection technologies. Some platforms lack a continuously updated source of threat intelligence data or, worse, any intelligence generation services at all. Companies must turn to external solutions that, through detection systems, sensors and other information-gathering mechanisms, summarize the data of potential new attackers, existing threat actors and suspects. With this data, the providers of these services are responsible for validating the incoming traffic of the mail server before it reaches our network or users.

Layer 2: Perimeter Protection

It is critical to validate that our perimeter protection systems have spam detection services. While most organizations use firewalls to provide perimeter protection to internal networks, many internal computers also have spam detection capabilities. It is also important to confirm that, once activated, the services are correctly configured and equipped with a robust reporting system that allows us to quickly identify emails classified as spam. Finally, we must configure a quarantine system to isolate false positives.

Layer 3: Internal Network, Mail Servers and Antispam Solutions

Confirming that our email systems have antispam services may seem very basic and simple, but they are often configured and implemented incorrectly. While many next-generation email platforms have local spam protection services, teams must check that these services are properly configured and pointing to the updated internal antispam servers.

If you do not have an internal antispam mail server, open source options such as RadicalSpam, SpamAssassin, MailScanner, OrangeAssassin and iRedMail can provide solid protection and threat data to block attackers. They must also have information providers that deliver frequently updated and valid threat intelligence.

Layer 4: Final Devices

Each host should have a protection mechanism connected to the mail client. Similar to a centralized system on a server, this mechanism must be able to detect threats, spam emails and spear phishing attacks. These systems are usually implemented in corporate or personal antivirus systems and connect to mail clients such as Outlook, Notes, Thunderbird and others.

Layer 5: Training End Users to Avoid Phishing Attacks

Users represent one of the most important layers of protection. All organizations should implement training programs and internal tests to gauge employees’ overall security awareness.

At the training level, educate users about the types of attacks they might encounter — especially spear phishing attacks — that could compromise critical enterprise assets. It is also necessary to conduct frequent tests to measure users’ susceptibility to phishing or spam campaigns. Most open source and commercial platforms have mechanisms for detecting these types of threats, but ensuring employees don’t fall for these schemes is vital.

Don’t Take the Bait

While these security mechanisms are known to many security professionals and executives, it is critical to establish basic policies, procedures, user guidelines and protection systems to safeguard company data from phishy fraudsters. With a layered approach to spam and phishing prevention, security teams can ensure that their employees and partners stay off the hook.

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