This year has seen a big shift in the exploit kit landscape, with many of the bigger players unexpectedly dropping out of action. The Nuclear exploit kit operations started dwindling in May, Angler disappeared around the same time Russia’s Federal Security Service made nearly 50 arrests last June, and then in September Neutrino reportedly went private and shifted focus to select clientele only. Now, the most prominent exploit kits in circulation are RIG and Sundown. Both gained prominence shortly after Neutrino dropped out of active circulation.
Sundown is something of an outlier from typical exploit kits. It tends to reuse old exploits and doesn’t make an effort to disguise their activity. The URLs for Sundown requests for Flash files end in .swf, while Silverlight requests end in .xap. These are the normal extensions for these file types. Typically, other exploit kits make an effort to hide their exploits. In addition, Sundown doesn’t have the anti-crawling feature used by other exploit kits.