PALO ALTO, Calif. — Declaring that the Internet has become the “Wild Wild West” with consumers and industries as top targets, President Obama on Friday called for a new era of cooperation between the government and the private sector to defeat a range of fast-evolving online threats.

Mr. Obama signed an executive order urging companies to join information-sharing hubs to exchange data on online threats — and, in some cases, to receive classified information from the government. But the order stopped short of exempting the companies from liability if the data they collected and shared led to legal action.

Only legislation, which Mr. Obama has tried and failed to get through Congress for three years, can exempt the companies from such liability. Many companies outside the financial industry have been reluctant to share data without such a law in place.

Mr. Obama deliberately chose Stanford University as the site of the first summit meeting on online security and consumer protection, saying that it was where much of the Internet was born and is also where the innovations to secure it must be developed.