At least tens of thousands of Microsoft customers may have been hacked by allegedly China-linked threat actors since January. Attacks started in January, but the attackers activity intensified in recent weeks. Attackers exploited a zero-day server-side request forgery (SSRF) vulnerability in Microsoft Exchange (CVE-2021-26855) Microsoft confirmed the attacks against the Exchange servers aimed at stealing emails and installing malware to gain persistence in the target networks. China has denied any involvement in the recent attacks.”]
Source: https://securityaffairs.co/wordpress/115359/apt/chinese-hackers-microsoft-exchange.html