If a malicious user takes your permissions for say animations there is currently no way to revoke those permissions.

"Avatar > Stop Animations" only stops and revokes permissions if the malicious object is rezzed in the region, if the object is a attachment or HUD attachment "Stop Animations" will temporarily stop the animation but does not revoke permissions allowing the object to just replay animations again.

This has been tested on the official Second Life viewer, Alchemy, and Firestorm all with the same results.