The Data Worm was a form of artificial intelligence that was able to gather data from computing systems.
It broke into the Archive of Islos to find forbidden knowledge for its owner involving the Dark Times and the Kotturuh. In its search for knowledge they found out more about the Vampires, the Hond, a member of the Lesser Order of Oberon, Mordeela, Rassilon, the Restoration Empire Daleks, and the Mechanoids.
Eventually the Archivians found out about this and trapped them inside and began to attempt to hunt it down. It provided a link to all the information it found out to its owner before it was ended by the Archivians. (PROSE: Secrets of Time Lord Victorious)