In one case, the hackers used a software flaw known as a zero-day vulnerability in one of the banks’ websites. They then plowed through layers of elaborate security to steal the data, a feat security experts said appeared far beyond the capability of ordinary criminal hackers. The incidents occurred at a low point in relations between Russia and the West. Russian troops continue to mass on the Ukrainian border and the West tightens sanctions aimed at crippling Russian companies, including some of the country’s most important banks.

http://www.bloomberg.com/news/2014-08-27/fbi-said-to-be-probing-whether-russia-tied-to-jpmorgan-hacking.html