On Sunday 31st May researchers identified a new critical vulnerability in Microsoft Office that allows a malicious actor to remotely execute code on a target system by exploiting Microsoft Diagnostic Tool (MSDT) and word template downloads.
The exploit enables an attacker to download a “template” for Microsoft Office that is actually an encoded PowerShell command. When this is analysed by the MSDT it is decoded and the code is executed on the target system.
Due to the nature of the vulnerability, the malicious files do not even need to be opened to execute the code.
This vulnerability poses a serious risk to organisations running Microsoft Office. However, while there is no official patch for the issue, temporary mitigations can be implemented.