Equation Group →
Going dark in 2014, the Equation Group's malware command and control servers have reportedly been migrated onto United States soil... This, after a nefariously successful run targeting thousands of victims in at least 40 countries. Focusing on vertical industry segments such as medical, telecom and aerospace sectors, including diplomatic missions, research institutions, military, governments, the Equation Groups' malware is apaprently fostering speculation as to connections between and betwixt US agencies.
"In an exhaustive report published Monday at the Kaspersky Security Analyst Summit here, researchers stopped short of saying Equation Group was the handiwork of the NSA—but they provided detailed evidence that strongly implicates the US spy agency." - via ArsTechnica's Dan Goodin