The changing face of email threats

No organization can afford to operate without an email security strategy. The risk landscape is constantly changing with new threats surfacing every day. This article looks at email security for mid-sized businesses, the solutions available and what features these organizations cannot do without.

In late 1971, a researcher from Bolt, Beranek and Newman (BBN) named Ray Tomlinson sent a text-based message between two computers sitting side by side in the company’s Cambridge, Mass. headquarters. The machines were connected only by the ARPANET, the precursor to the Internet, which BBN built for the US Department of Defense.

This seemingly inconsequential moment changed communications forever - Tomlinson had just sent the first-ever Internet-based email. Tomlinson developed email on his own, with no expressed need by customers or management. He and his team were simply charged with finding new ways to use the ARPANET, so he created email “because it seemed like a neat idea.”

Over 40 years later, Tomlinson’s “neat idea” has supplanted the telephone as the primary form of communication between and within many businesses.

But the very qualities that have built email’s success among legitimate users – low cost, ubiquity and ease of use – have also made it a powerful tool for criminals.

Ask the average worker about email, and they are as likely to mention its dark side – spam, malware and phishing attacks – as they are the positive side.

Similar concerns surface at a corporate level, but they are more complex. Ask the average security or compliance officer about email, and they are just as likely to complain about outbound email threats – information leakage, compliance violations and legal liability from inappropriate content – as they are about inbound ones.

The security industry has provided large businesses with effective email security solutions for many years, helping to address their heightened sensitivity to email risk.

Email gateway security solutions have proven particularly effective, because they filter inbound and outbound email traffic at the email gateway, thus ensuring that only emails conforming to corporate policy are allowed in and out of the business. Because these solutions remove unwanted email before it reaches the email gateway, they also reduce bandwidth consumption in corporate networks.

Mid-sized businesses historically have been less aggressive toward email security, due to lower perceived risk and a general lack of full-featured solutions suitable to their budgets and environments.

Today, however, these companies face a constant barrage of spam, viruses and other malware that can cause significant business harm, ranging from impaired productivity to lost business and brand damage.

News headlines frequently tout the proliferation of email-based spam and malware. In 2014, two thirds of all email traffic was spam. For mid-sized businesses, spam and viruses have traditionally been a nuisance and productivity hindrance, so deploying antispam and antivirus solutions that could block most of this traffic was considered good enough.

The changing face of email threats more recently, however, the threat landscape has changed. Criminal organizations have evolved from targeting a select number of large businesses to targeting large numbers of businesses of all sizes. Midsized businesses are particularly attractive to them, since they tend to have fewer defenses than their larger cousins. They are targeting these companies with a broader array of motivations and tools than ever before, including:

• Traditional spam attacks.
• Malware attacks, where emails include malware as file attachments or links to malicious websites.
• Phishing attacks, to trick recipients into visiting spoofed websites that request personal identity information or download malware onto the computer.
• Denial of service attacks, which can block email capabilities by bombarding email servers with a flood of messages.
• Spear phishing attacks, which are targeted attacks on specific people. These attacks are designed either to steal personal identity information or to gain control of their computers so they can be used to penetrate corporate networks.
• Directory harvest attacks, where spammers try and identify valid email addresses in an organization. They do this by bombarding it with emails sent to addresses using a variety of common names.

The potential damage from these attacks extends beyond impaired productivity. In the early days of email spam, most unwanted mails were marketing messages for products and services, legitimate and illegal alike.

As attackers became more sophisticated, their spam content took a more malicious turn. Unwanted email can now also cause more serious problems including data breaches, financial loss, compromised customer information, compliance violations and brand damage.

In many cases, malware delivered via email is designed to provide criminal organizations with control over the infected computer. They may use it for any number of purposes, including:

• Stealing personal identity information.
• Adding the compromised machine to a botnet, where it can be used for anything from sending spam or hosting illegal content.
• Siphoning sensitive information directly from the computer.
• Using the computer as a foothold to gain access to other parts of the network and launch a wide-ranging attack on the network.

This last attack can be particularly damaging for large and small companies alike. Once inside a network, attackers can stealthily gather all kinds of corporate data, including a customer or employee databases, customer credit card information, negotiating documents or intellectual property such as product prototype details. Infiltration of a company’ systems could also allow that organization’s network to launch attacks on the networks of partners or customers to which the company has access.

Outbound email represents another set of risks for mid-sized companies, including compliance violations, legal liability and general business damage from information leakage and inappropriate email. Today, many companies of this size today do not monitor outbound email, nor do they have acceptable use policies in place, so they are virtually unprotected against these risks.

To combat modern email threats, companies need to deploy comprehensive and cost-effective email security solutions that can cleanse both inbound and outbound traffic, to reduce overall risk to the business.

Key features of an email gateway

• security solution
• Most email gateway security solutions will include antispam and antivirus engines. However, truly reducing email risk requires a number of additional features that address the full spectrum of threats posed by inbound and outbound email.

Key features to consider when evaluating gateway solutions include:

• Configurability - Ease of use is important, but it should not come at the expense of configurability. The email security gateway solution should have enough configuration options so that they can be customized to specific business requirements.
• Multiple antivirus engines - Defense-in-depth strategies were once only available to large businesses. Today, you should seek similar capabilities for your clients. Because no antivirus engine is perfect, you should adopt email gateway security solutions that use multiple such engines to improve overall antivirus effectiveness.
• Filtering for email exploits - Email exploit engines attempt to detect unknown malware. They do this by analyzing suspect code and determining whether or not it has the characteristics of malware. This is a critical capability for email security solutions because it defends against malware exploiting vulnerabilities that have not been publicly revealed, or patched. Called a zero-day attack, this type of threat is increasingly common.
• Anti-phishing engine - Anti-phishing engines reveal the true domain names of spoofed websites promoted in phishing emails. This decreases the likelihood of the user falling prey to a phishing attack.
• Intelligent spam filtering - Anti-spam vendors are notorious for publicizing inflated effectiveness rates. So you should focus not just on detection rates, but also on the corresponding false positive rate.

Effectiveness and detection rates have a direct correlation: The higher the detection rate, the higher the false positive rate, and vice versa. Since a single false positive can be far more damaging than allowing multiple spam messages to enter the network, it is important to be able to configure the spam filter so it strikes the right balance to protect the business, while enabling fluid communication. The anti-spam engine should also be able to learn from user behavior, so it does not impede the flow of business communication.

For example, Vicodin and other painkillers are common in spam solicitations, but in health care organizations they are also the topic of legitimate email correspondence. A good anti-spam engine should be able to learn the difference between spam and legitimate emails in this type of situation so it does not bog down the business with excessive false positives.

A competent anti-spam engine should also be able to receive updates automatically from the vendor to keep pace with changing spam techniques. This maintains its effectiveness when new forms of spam appear, as we have seen over the years with non-delivery report, attachment, or image-based spam.

• Self-service spam quarantine - Maintaining spam quarantines is a tedious, low-value activity for IT administrators. An effective SMB email gateway security solution will provide self-service quarantine administration, so end-users can review their own quarantines and unblock or delete messages themselves. This frees you up to focus on more value-added activities, which is especially important for companies with limited support/budgets.
• Data loss prevention (DLP) - As mentioned earlier, outbound email presents a broad array of risk to SMBs. Employees accidentally or intentionally leaking confidential or inappropriate information can lead to lost business, public embarrassment, compliance violations and even legal exposure. You should look for DLP functionality in any email gateway security solution so you can mitigate these risks through a combination of attachment and content filtering.