Microsoft Office 365 email encryption could expose message content

14-Oct-22

The adoption of a weak block cypher mode of operation makes it feasible to partially or completely infer the contents of encrypted messages sent through Microsoft Office 365, according to security researchers at WithSecure, formerly F-Secure Business.

Office 365 Message Encryption is a tool used by businesses to protect the content’s secrecy from source to destination when sending or receiving emails, both internal and external. The feature uses the Electronic Code Book (ECB) mode to encrypt the data, however under some circumstances it is possible to deduce the plaintext message. Read More…