Mail/Web Filtering Recommendations

We recommend that many different file types are blocked by default in all email and web filtering systems. Generally, these are the sorts of files that you would not expect anyone to receive by email.

There is a significant risk of users, both skilled and unskilled IT professionals, opening attachments, or downloading certain file types, which may cause harm to our systems or indeed, worst case, generate a breach and ultimately data loss. 

Whilst a Computer Forensics Expert (generally a post-breach support provider) or any Cyber Security Professional would suggest you block all file types and allow only those required within the business, we understand that this is not practical, therefore, we recommend blocking, at least, the file types listed below, which will ensure that some of the riskiest file types are blocked from entering your systems via email.

Many email platforms will block some of these, but not all, and indeed, many systems, such as Outlook, block different files depending on the operating system they are installed on, for example, Outlook Mac blocks different files than Outlook Windows, which is odd, but is the case, and also, doesn't block all the file types below.

In addition, many companies use mail filtering solutions outside of the core messaging platform, thus, instead of MS365 or GSuite, an additional product is used - we have also found that many of the file types below are not blocked by those solutions either, so adding these is a great idea.

You should also consider adding these to any web filtering blocks to prevent download and execution from websites that may have been compromised.

KNOWN RISKY FILES

LINUX FILE TYPES

MICROSOFT WINDOWS FILE TYPES

MAC OS FILE TYPES

LINUX FILE TYPES

MIXED OS FILE TYPES

ANDROID FILE TYPES

IOS FILE TYPES

GEM FILE TYPES

CHROME FILE TYPES