By Ionut Arghire on March 11, 2021
At least 10 threat actors are currently involved in the targeting of Microsoft Exchange servers that are affected by recently disclosed zero-day vulnerabilities, according to cybersecurity firm ESET.
On March 2, Microsoft announced patches for four bugs (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065) that were part of a pre-authentication remote code execution (RCE) attack chain already being exploited in the wild.
Successful exploitation of the bugs could result in the attacker deploying webshells onto the vulnerable Exchange servers, potentially taking full control of them. To date, ESET has identified more than 5,000 compromised servers, but others previously reported that tens of thousands of organizations may have been hacked.