An ActionScript error has occurred: SecurityError: Error #2060:

Lately I have seen a lot of strange popups when browsing news sites in IE 11. The popups appear in an OS window (as opposed to a window created inside the web page). The popup window has the title "An ActionScript error has occurred". The text inside the popup starts with: "SecurityError: Error #2060: Security sandbox violation: ". What is strange is that these popups appear despite the fact that I made sure that Flash is not installed on my system. Also I verified that IE does not have any Flash add-on installed or enabled.

Is anyone else seeing these type of popups? Any chance this is a sign of a vulnerability or attack?

Here is an example of a complete error text:


SecurityError: Error #2060: Security sandbox violation: ExternalInterface caller http://video.ybpangea.com/SyndPlugins/tzukPlayer.swf cannot access <unknown>.
 at flash.external::ExternalInterface$/_evalJS()
 at flash.external::ExternalInterface$/call()
 at com.hiro.streaming::AdNetworksEventsHandler/reportAdNetworkEvent()
 at com.hiro.streaming::HiroLayer/reportAdNetworkEvent()
 at MethodInfo-269()
 at com.hiro.util.bidding::BiddingArena/loadAd()
 at com.hiro.util.bidding::BiddingArena/onExternalAdNetworkReponse()
 at com.hiro.util.AS3::XMLLoader/xmlLoaded()
 at flash.events::EventDispatcher/dispatchEventFunction()