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4 Email Attachment Threats to Secure Systems From

Malicious emails remain some of the most common and destructive computer security threats faced by businesses today. According to research by Verizon, email as a threat vector represents 96% of cyberattacks carried out across various industries. Cybercriminals use email-based attacks to steal login credentials, lure individuals into clicking malicious links, and deliver malware. Managed services providers (MSPs) have the dual role of protecting both their own employees and their customers from such attacks. To do so effectively, it is crucial that MSPs and their customers know the most common email attachment threats and employ robust email threat protection tools to help secure their customers’ systems.

Email attachment risks for MSPs

As an MSP, you’ve worked hard in the past to prevent or mitigate the consequences of malware—but it’s likely that many of your customers don’t understand what malware entails. Explaining malware in layman’s terms to your customers can go a long way in helping illustrate the threat it poses.

Malware is a generic term that refers to malicious software. This encompasses worms, spyware, computer viruses, or trojan horses. Malware is often delivered via email attachment as an executable file (with a .exe file extension) or even as what “appears” to be a harmless text file (with a .txt extension). Many malicious email attachments have hidden extensions designed to fool the recipient into downloading the file without thinking twice. Some malware can even be embedded in images, including PDF and JPEG files. These activate when they are opened and are likely to appear to be the same as any other harmless image or PDF document.

What damage can malware actually do? As mentioned, malware is especially dangerous to MSPs. By deleting files from your hard drive, corrupting data, or even disabling your mobile devices or computer, malware has the ability to compromise your data as well as your customers’. For example, certain malware will have specific functions, which might include writing code on your hard drive. This code could then be used to turn your machine into a zombie (which can be controlled by a hacker remotely), spy on your activities, or send confidential data to an external location.

Imagine that malware successfully shares your customers’ sensitive data with another party. If this happens, you and your customers could be made vulnerable to fraud, with banking information stolen and cash extracted from your account. There is also the risk of identity theft and credit card fraud. This is just one simple example of why failing to employ the appropriate email threat protection practices can leave you liable for some serious damages.

Email-based strategies used by cybercriminals

It’s important to remember that email authors with malicious intentions are often clever. They continuously evolve their strategies to develop new ways of deceiving and attacking individuals and businesses alike. Although their strategies will vary, there are three basic approaches employed by most cybercriminals:


These dangerous links are often featured directly in the body of the email. This type of threat accounts for a high number of data breaches, with Dark Reading summarizing the findings of a FireEye report that malicious URLs were even more common than email attachments in attacks, often using HTTPS links.


This approach involves cybercriminals using social engineering to convince their victims to transmit sensitive information or perform a financial transaction. This approach does not require links or attachments.


Cybercriminals will often send emails with malicious attachments. These attachments can install ransomware, keyloggers, and other malware on the victim’s device when opened.

These three strategies account for almost all forms of malicious emails employed by cybercriminals.

Top 4 email attachment threats

With malicious email attachments representing a lion’s share of successful malware deliveries, it’s important to examine the most common types of email attachment threats to understand how bad actors operate. Here are the top four email attachment threats that MSPs are likely to encounter.


Ransomware encrypts a victim’s data and demands or blackmails them into paying a fee to restore said data. Ransomware is delivered via email attachment and executed when the victim opens the attachment.


This tactic uses psychological and social manipulation to lure victims into divulging sensitive information that cybercriminals can then sell for malicious purposes. The message is designed to trick the recipient and the sender is designed to look authentic, making the victim believe that the email was sent by a trusted individual, or business. This baits them into opening infected attachments without thinking critically about what these attachments might include.


In severe data breaches, user credentials are almost always stolen. To pull this off, cybercriminals often use keyloggers to steal IDs and passwords. The keylogger can be stored in an email attachment and executed when opened, or when the victim clicks a malicious link. From there, the keylogger can record keys pressed on the user’s keyboard to capture passwords and other relevant account details.


This type of attack targets zero-day vulnerabilities, which are security weaknesses unknown to the software developer. These are usually security vulnerabilities that are exploited before the vendor can fix them. Zero-day attacks are often delivered by email and are sometimes stored in attachments, giving hackers unauthorized access to sensitive information.

Choosing your MSP’s email security tools

It is key that you take email threat protection, email continuity, spam filtering, and practices for archiving into consideration when developing your email services for customersSolarWinds® Mail Assure can help you address each of these email components while still helping ensure you’re enabling continued productivity and minimal downtime for your customers. To combat modern threats with ease, many MSPs depend on Mail Assure to protect both their customers and businesses from email-based attacks.

This tool delivers advanced spam protection with proprietary inbound filtering technology that incorporates data from more than 23 million mailboxes to safeguard against new threats. With a filtering accuracy rate of 99.999%, you can rest assured that your customers are able to conduct normal business via email without fear of malicious attachments.

Mail Assure also includes an easy-to-install Microsoft 365 add-in, which gives you seamless integration as well as offering users greater transparency and control over their email. Additionally, a new Sync for Microsoft 365 simplifies onboarding of your Microsoft 365 customers. If you are looking for protection against viruses, malware, spam, ransomware, phishing attacks, and other email-based threats, Mail Assure comes highly recommended. A 30-day free trial is available if you’re interested in learning more.

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