Quote:Servers used to show adverts on a popular YouTube to MP3 conversion website have been compromised in order to spread the GreenFlash exploit kit and Seon ransomware. 
 
Malvertising is a technique used by hackers and scammers to reach a wide audience, often on legitimate domains and services. Malicious code or links will be embedded within an advertisement which is then displayed to unwitting website visitors, and should they click the link, they may be directed to a fraudulent website or be issued a malicious payload. 

The problem with malvertising is that sometimes malicious ads will slip through the net and legitimate domains that rely on adverts for revenue will become the distributors of malware without realizing it. 

Quote:In a blog post, Malwarebytes researcher Jérôme Segura said on Wednesday that the exploit kit, deemed "elusive" and generally only spotted in Asia, is now expanding. 

The malware has been spread through servers used to deliver ads by multiple publishers, including on onlinevideoconverter[.]com, a service which transforms YouTube videos into audio files. This website alone caters for over 200 million users per month, according to SimilarWeb.