Filmmaker Alex Gibney is known for his awardwinning documenteries on topics that range from Enron to Wikileaks, but now he's taken on a tough challenge: Making a movie about a secret program that few people will publicly acknowledge. "Zero Days" focuses on the Stuxnet computer virus that's believed to be the world’s first digital weapon. News outlets had reported that both the US and Israel were behind the virus designed to slow down Iran's nuclear program – but even now, years after the attack on Natanz uranium enrichment plant, and long since researchers discovered Stuxnet on computers in other countries, the making of Stuxnet is still shrouded in secrecy.