Warning issued on Office 365 mail vulnerability, but Microsoft denies problem

Use of ECB encryption shown to leave mail vulnerable in security firm’s tests.

Cybersecurity company WithSecure has published details of a vulnerability in Microsoft Office 365 Message encryption (OME), but Microsoft is so far refusing to acknowledge there is a risk that needs addressing.

WithSecure says the problem comes from Microsoft’s decision to use a block cypher confidentiality mode called Electronic Codebook (ECB). A

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