Australian corporations hit by massive Microsoft Server hack Australia's cyber security watchdog has urgently warned Aussie corporations using Microsoft Exchange products to urgently patch their software after it was compromised by hackers. Microsoft Exchange Server holds millions of corporate emails, calendars and rostering products and if hacked entire email inboxes could be wiped as well as stolen. The Australian Signals Directorate's Australian Cyber Security Centre (ACSC) today confirmed Australian organisations â thought to be over 7000 servers locally - had been affected by the hack. READ MORE: The hack has affected Microsoft Exchange Server around the globe.(AP) Ladislav Zezula, Malware Analyst at antivirus provider Avast, said the hack could be potentially very damaging for corporations.