A malvertising group recently targeted Apple users in a campaign that delivered a payload hidden in advertisement images. The attack triggered at least 5 million times a day. The group only recently resorted to steganography to conceal redirect code leading to a fake Flash update. An analysis from Malwarebytes shows that the phony update is a macOS adware installer known as Shlayer. At the moment of writing, the malware is detected by 14 antivirus engines available on the VirusTotal platform. The costs associated with this timeframe are estimated to be in excess of $1.2 million.
Source: https://www.bleepingcomputer.com/news/security/verymal-malvertiser-delivers-image-based-malware/