HAFNIUM has exploited CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065  to compromise on-premises versions of Microsoft Exchange Server, enabling access to email accounts and installation of additional malware.(Citation: Microsoft HAFNIUM March 2020)(Citation: Volexity Exchange Marauder March 2021)(Citation: FireEye Exchange Zero Days March 2021)(Citation: Tarrask scheduled task)   |