GTSC, a cybersecurity company based in Vietnam, reported seeing attacks exploiting two new Microsoft Exchange zero-day vulnerabilities. The firm believes the attacks, which were first seen in August and aimed at critical infrastructure, were launched by a Chinese threat group.

Technical details on the vulnerabilities have not been made public, but GTSC did say that the threat actor’s post-exploitation activities included the deployment of backdoors, lateral movement, and the delivery of malware.