Dire warnings from Washington about a "cyber Pearl Harbor" envision a single surprise strike from a formidable enemy that could destroy power plants nationwide, disable the financial system or cripple the US government.
But those on the front lines say it isn't all about protecting US government and corporate networks from a single sudden attack. They report fending off many intrusions at once from perhaps dozens of countries, plus well-funded electronic guerrillas and skilled criminals.
Security officers and their consultants say they are overwhelmed. The attacks are not only from China, which Washington has long accused of spying on US companies, many emanate from Russia, Eastern Europe, the Middle East, and Western countries. Perpetrators range from elite military units to organized criminal rings to activist teenagers.
"They outspend us and they outman us in almost every way," said Dell Inc's chief security officer, John McClurg.
"I don't recall, in my adult life, a more challenging time." The big fear is that one day a major company or government agency will face a severe and very costly disruption to their business when hackers steal or damage critical data, sabotage infrastructure or destroy consumers' confidence in the safety of their information.
Elite security firm Mandiant Corp on Monday published a 74-page report that accused a unit of the Chinese army of stealing data from more than 100 companies. While China immediately denied the allegations, Mandiant and other security experts say the hacker group is just one of more than 20 with origins in China.
Chinese hackers tend to take aim at the largest corporations and most innovative technology companies, using trick emails that appear to come from trusted colleagues but bear attachments tainted with viruses, spyware and other malicious software, according to Western cyber investigators.