Malware was hiding modules in WAV audio files and spread to vulnerable Windows 7 machines on the network via EternalBlue, the exploit for SMBv1 used in the WannaCry and NotPetya cyber attacks from 2017. The attack is not sophisticated, it shows that some mid-size organizations are ill-prepared to defend against a cybersecurity incident and set up the environment to support post-infection analysis efforts. The victim company used Windows 7, an operating system that on Tuesday received its last batch of updates and is no longer supported by Microsoft.
Source: https://www.bleepingcomputer.com/news/security/windows-bsod-betrays-cryptominer-hidden-in-wav-file/