In a chilling demonstration of stealth and strategy, APT19, also known as Deep Panda, executed a sophisticated cyberattack on Anthem, one of the largest health insurance providers in the United States. The breach resulted in the exposure of 78.8 million patient records, revealing a calculated phishing campaign targeting IT administrators, the deployment of custom 'Derusbi' malware, and an unusual lack of encryption on the stolen database. As an investigator, you will delve into the intricacies of this operation, following the digital breadcrumbs left by the attackers.