What is the definition of Sigmavirus?

Sigmavirus: Picture this - it's like a sneaky, high-tech virus that lurks in the shadows of our computer systems, disguised as a harmless sigmoid-shaped protein. It's named after the S-shaped curve it resembles when plotted on a graph, hence 'igmo' - a nod to sigmoids in math and virology. Now, here's an edgy example: "The Sigmavirus infiltrated my computer system like a mischievous ninja, turning my precious data into pixelated gibberish and demanding a ransom in the form of my personal photos."