A popular Adserver had been compromised and scripts were modified in such a way that instead of just ads, malware was also delivered to the visitor. This news comes after reports of other (ad)servers being compromised, all using Exploit.HTML.Iframebof to infect the system with malware. Kaspersky Lab strongly recommends anyone using MS Windows, but not running XP/SP2, to use an alternative browser to avoid the malware. A more detailed article on this subject will be posted soon on viruslist.com.”]
Source: https://securelist.com/adserver-compromised-legitimate-sites-serving-malware/29895/