By Michael Isikoff
NBC News National Investigative Correspondent
COLUMBIA, S.C. -- A single malicious email sent to workers at the South Carolina Department of Revenue last August enabled an international hacker to crack into state computers and gain access to 3.8 million tax returns, including Social Security numbers and bank account information, in what experts say is the biggest cyber-attack ever against a state government, according to details in a report released Tuesday.
“We were a cocktail for an attack,” Gov. Nikki Haley said, referring to the necessary ingredients for cyberassault, as she released a report by a computer security firm Mandiant, which was commissioned to investigate the data breach. At the same time, Haley accepted the resignation of her Department of Revenue director, Jim Etter, and acknowledged that state officials “could have done more” to protect the personal data of state residents.