Warnings also came from Danish cyber security provider Dubex, which first witnessed clients being hit on 18 January. The company reported their incident response findings to Microsoft on 27 January. In a blog post, Dubex detailed how hackers took advantage of the 'unifying messaging' module in Exchange, which allows organisations to store voicemail and fax files, as well as emails, calendars, and contacts in users’ mailboxes, in order to install web shell backdoors. “A unified messaging server also allows users access to voicemail features via smartphones, Microsoft Outlook and Outlook Web App. Most users and IT departments manage their voicemail separately from their email, and voicemail and email exist as separate inboxes hosted on separate servers. Unified Messaging offers an integrated store for all messages and access to content through the computer and the telephone,” Dubex revealed.