As you may know, ASF files are used with WMA-, WMV- or MP3 formatted content that enables Microsoft to check whether a song or video has been obtained legally. Windows media player checks the files license and also links to industry web sites to clarify licensing issues. However, fraudsters are now crafting ASF files so that users are sent to sites which invite them to download malware, usually in the form of a plugin or similar tool so the users can play the video.

VirusTotal is now able to help detect exploit attempts made using video and music files in ASF format. Users can upload suspect ASF files of up to 64MB in size to VirusTotal.