Email attachments are very important to most businesses. However, they can be used to spread malware infections, gain access to your IT infrastructure and leak confidential information. You always need to ensure that your company’s email attachments are as secure as possible.
Block dangerous attachment formats
A good starting point is to create a policy that blocks all email attachments that use potentially dangerous formats e.g. .exe files or password protected zip files. If your company sends these file formats legitimately, use tools like Dropbox or a portal to securely transfer files.
There is often lag time between the appearance of a new malware threat and when anti-malware engines can detect it. This exposes organizations if they are only using one anti-virus engine. Using four or more anti-virus engines significantly increases the chance that any new malware will be quickly detected and quarantined.
Don’t send confidential information via email attachments
Data like credit card information or social security numbers should never be sent via email. Email policies should be set up to block any email attachments that contain information of this kind so no sensitive data gets leaked into the public sphere. Alternative methods should be provided for transferring files securely so that users don’t have to resort to email.
Sanitize email attachments
The battle against malware and viruses changes daily. Targeted attacks, like the recent Sony hack, zero-day attacks and new malware with no anti-virus definitions can get past your anti-malware engine and end up in your users’ mailboxes. As these threats will be unknown, email attachments should be sanitized by converting files to a different format and removing any possible embedded threats. For example, converting a Word document into a PDF will remove any potentially harmful scripts before they do any damage.
Beware of spoofing
Hackers often use increasingly cunning methods of fooling people into opening harmful attachments. One method used is to rename extensions so that malicious files look harmless. Making an .exe file look like a .txt file means that a user is more likely to think that the attachment is safe. If there is every any doubt into the authenticity of an attachment, it is best to be delete it immediately.