Trend Micro has issued a report detailing in the wild exploitation of a publicly disclosed vulnerability in Microsoft Word. According to VirusTotal timestamps, the first wave of exploitation began on October 31, 2018. The vulnerability was disclosed on October 25.
Vulnerable component: Microsoft Word
CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:H/RL:U/RC:C
CWE-ID: CWE-20 - Improper Input Validation
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The weakness exists due to a logical bug is revealed when embedding a video via the 'online video' feature. A remote attacker can embed a video inside a Word document, edit the XML file named document.xml, replace the video link with a crafted payload created by the attacker which opens Internet Explorer Download Manager with the embedded code execution file and execute arbitrary code with elevated privileges.
Successful exploitation of the vulnerability may result in system compromise.
Note: as of October 31, 2018 the vulnerability is being actively exploited in the wild.