A secretive branch of China's military is probably one of the world's "most PROLIFIC cyber espionage groups", a US cyber security firm has said.

Mandiant said Unit 61398 was believed to have "systematically stolen hundreds of terabytes of data" from at least 141 organisations around the world.

It traced the attacks to the doorstep of a non-descript building in SHANGHAI used by the unit.

China denied hacking and questioned the validity of Mandiant's report.
'Extensive cyber espionage'

"Hacking attacks are transnational and anonymous," said foreign ministry spokesman Hong Lei.

"Determining their origins are extremely difficult. We don't know how the EVIDENCE in this so-called report can be tenable.

Full story: http://www.bbc.co.uk/news/world-asia-china-21502088It pretty much cannot be "denied" or explained away since all the source tracking was done by the Governments cyber security arm...
I gotta believe they're kinda good at what they do." "Determining their origins are extremely difficult." True of COURSE but not impossible. Depends on the degree of stealth and the corresponding degree of COMPETENCE of equipment and knowledge/abilities of the sleuth i would say.truenorth