AppNexus is the origin of a recent “malvertising” campaign that makes use of the Angler Exploit Kit to redirect visitors to malicious websites hosting the Asprox malware. Last week, users of several high-profile websites were redirected to malicious advertisements that infected visitors by installing botnet malware on their computer. The Angler exploit kits are available on the underground black forums and are used in various malicious campaigns to own websites and redirect users off to websites hosting banking malware and other types of malicious code to victimize them.
Source: https://thehackernews.com/2014/08/malicious-advertisement-found-on_29.html