By Ionut Arghire on March 12, 2021 In addition to state-sponsored threat actors, the recently disclosed vulnerabilities affecting Microsoft Exchange Server are now being targeted by ransomware operators. A total of four critical zero-day vulnerabilities that are collectively referred to as ProxyLogon were patched in Exchange Server at the beginning of this month, and activity surrounding the bugs has only intensified since. This week, ESET revealed that it has identified at least 10 threat actors that are attempting to exploit these vulnerabilities in their attacks, including Calypso, LuckyMouse (also tracked as APT27), Mikroceen, ShadowPad, Tick (also known as Bronze Butler), Tonto Team (CactusPete), Websiic, Winnti Group (BARIUM, APT41), and DLTMiner.