Threat actors are sharing Windows MSHTML zero-day (CVE-2021-40444) tutorials and exploits on hacking forums, allowing other hackers to start exploiting the new vulnerability in their own attacks. On 7th September, Microsoft disclosed a new zero-day vulnerability in Windows MSHTML that allows threat actors to create malicious documents, including Office and RTF docs, to execute commands on a victim's computer remotely. After the vulnerability was disclosed, Microsoft Defender and other security programs were configured to detect and block parts of this attack.While these mitigations will help, as the exploit has been modified not to use ActiveX controls, users are still at risk until an official security update is released. Until Microsoft releases a security update, everyone should treat all Word and RTF attachments suspiciously and their source manually verified before opening them.