Computer attacks on Google that the search giant said originated in China were part of a concerted political and corporate espionage effort that exploited security flaws in e-mail attachments to sneak into the networks of major financial, defense and technology companies and research institutions in the United States, security experts said…

Security experts say the attacks showed a new level of sophistication, exploiting multiple flaws in different software programs and underscoring what senior administration officials have said over the past year is an increasingly serious cyber threat to the nation’s critical industries.

“Usually it’s a group using one type of malicious code per target,” said Eli Jellenc, head of international cyber-intelligence for VeriSign’s iDefense Labs, a Silicon Valley company helping some firms investigate the attacks. “In this case, they’re using multiple types against multiple targets — but all in the same attack campaign. That’s a marked leap in coordination.”