A critical vulnerability (CVE-2018-4878) exists in Adobe Flash Player 28.0.0.137 and earlier versions. Successful exploitation could potentially allow an attacker to take control of the affected system.

Adobe is aware of a report that an exploit for CVE-2018-4878 exists in the wild, and is being used in limited, targeted attacks against Windows users. These attacks leverage Office documents with embedded malicious Flash content distributed via email.

Adobe addressed this vulnerability in version 28.0.0.161, released on February 6, 2018.  See this bulletin for more details.  

Affected Product Versions

To verify the version of Adobe Flash Player installed on your system, access the About Flash Player page, or right- click on content running in Flash Player and select "About Adobe (or Macromedia) Flash Player" from the menu. If you use multiple browsers, perform the check for each browser you have installed on your system.

Mitigations

Beginning with Flash Player 27, administrators have the ability to change Flash Player's behavior when running on Internet Explorer on Windows 7 and below by prompting the user before playing SWF content.  For more details, see this administration guide.   

Administrators may also consider implementing Protected View for Office.  Protected View opens a file marked as potentially unsafe in Read-only mode.  

Vulnerability details

Acknowledgments

Adobe would like to thank KrCERT/CC for reporting this issue and for working with Adobe to help protect our customers. 

Revisions

February 8, 2018: Added a reference to APSB18-03, which announced the update (28.0.0.161) that resolved CVE-2018-4878.  Also added a note indicating that the ActiveX component in Adobe Connect was not impacted by CVE-2018-4878.