https://www.bleepingcomputer.com/news/security/lost-files-data-wiper-poses-as-a-windows-security-scanner/

A Windows Security Scanner that states it encrypted your files is being distributed by spam, but whether by bug or design, it instead corrupts binary data in a victim's files. 

ISC Handler Xavier Mertens received a spam email that pretends to be from Microsoft and has a subject of "Virus Detection On Your Computer!". The email then proceeds to state that a Trojan horse was detected on the computer and that the recipient should download the linked to "security scanner".