(Reuters) – The websites of Las Vegas Sands’ casinos around the world on Thursday remained down for a third straight day, as the company and U.S. federal investigators race to unravel a hacking attack that defaced home pages and also exposed sensitive employee information. But it has verified that “certain” core operations had not been affected, spokesman Ron Reese said. Reese said the company was cooperating with the Federal Bureau of Investigation and other federal authorities in the current investigation.