The vulnerability was being actively exploited since mid-March, 2012. The targeted attacks were focusing on Japanese organizations.
Advisory: SB2012071001 - Remote code execution in Microsoft Office
Vulnerable component: Microsoft Office
CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C
CWE-ID: CWE-426 - Untrusted Search Path
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to the way Microsoft Office loads .dll libraries when opening Office documents (such as a .docx file). A remote attacker can place a specially crafted .dll file along with Microsoft Office document on a remote SMB or WebDAV share, trick the victim into opening that document and execute arbitrary code on the target system with privileges of the current user.
Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.
Note: the vulnerability was being actively exploited.