This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.
This signature detects attempts to exploit a User After Free vulnerability in Adobe Flash Player.
Adobe Flash Player is a multimedia application for multiple platforms.
Adobe Flash Player is prone to a remote memory-corruption vulnerability because of a use-after-free error. Specifically, this issue exists in the ActionScript 3 'opaqueBackground' class.
Attackers can exploit this issue to execute arbitrary code in the context of the user running the affected applications. Failed exploit attempts will likely cause a denial-of-service condition.