Medusa is a creative name for any security program.  In classical mythology, she is the Gorgon known for turning anyone who chanced the sight of her into stone.  It is hoped that any unwanted programs or viruses that infect a system like magic tricks may happen upon the Medusa security program would so to turn to stone and lose their original function.  Although once beautiful and having human form, Medusa was cursed by the goddess Athena to forever have serpents for hair and turn all those who looked upon her to stone.  This was in retribution for the blatant disrespect shown by Medusa and Poseidon in gratifying themselves in Athena’s temple.