might not know about the hack if not for fireeye, a $3.5 billion cybersecurity company run by kevin mandia, a former air force intelligence officer. >> i can tell you this. if we didn't do investigations for a living, we wouldn't have found this. it takes a very special skill set to reverse engineer a whole platform that's written by bad guys to never be found. >> reporter: fireeye's core mission is to hunt, find and expel cyberintruders from the computer networks of their clients, mostly governments and major companies. but fireeye used solarwinds software, which turned the cyber hunter into the prey. this past november one alert fireeye employee noticed something amiss. >> just like everybody working from home, we have two fact authentication. a code pops up on our code, we have to type in that code, and then we can log in. a fireeye employee was logging in, but the difference was our security staff looked at the log-in and we noticed that individual had two phones registered to their name. so our security employee called that person up, and we asked, hey, did you actually register a sec