Common Attachment Blocking (CAB) is coming to EOP

UPDATE: Common Attachment Blocking has been released in EOP as the Common Attachment Types Filter. See my new article, Common Attachment Types Filter, for more information on this feature.


The following article was written by Rob McCarthy who is a Business Program Manager for Readiness in Microsoft.

We are happy to announce that Common Attachment Blocking (CAB) is coming to EOP.

In the not so distant future, administrators will have the ability to easily block certain file types coming in through email by checking a box! This will eliminate any chance for error that creating a file block through an Exchange Transport Rule often introduces.

By default, new tenants will have CAB enabled with ten specific file types already checked. Existing tenants will see the feature, but will have to manually enable it.

Once CAB is enabled, by default, ten (10) of the most common file types will already be checked. These ten files types were chosen by our analysts as not only the most common, but often the most likely to be able to transmit malware. Common Attachment Blocking is a big step forward in catching new forms of malware without having to wait for a virus definition to be developed.

In addition to an improved strategy defending against zero-day vulnerabilities, CAB simply allows administrators to block any file they want, for any reason, in a fast, mistake free method.

Please stay tuned for release date details!

- Rob McCarthy