Shadow Security Droids were small, hovering black-colored droids. Inside, they contained a unique and highly-specialized type of droid brain that had had the consciousness of a living being transplanted into it through use of a dark side technique. The droids were very dangerous and were armed with heavy repeating blasters. They had red-colored targeting diodes.
The Shadow Security Droids were one of the Empire's first experiments and were a precursor design to the much larger Shadow Droids.
A number of Shadow Security Droids were deployed aboard a Golan space defense platform in the Beshqek system. Four of them attacked a group of Alderaanian Resistance agents that boarded the platform during the Battle of Byss.