>Researchers have discovered malware so stealthy it remained hidden for six years despite infecting at least 100 computers worldwide.
Maybe I am reading it the wrong way, but if we are talking of around 100 computers worldwide, the "despite" doesn't seem to me appropriate.
Given the context and the published map of victims it is clearly a very "targeted" kind of malware, so if it was limited to those "declared" victims and it is so well designed (with reference to its stealthness) I am not surprised at all that it passed below attention.