without risk. When thousands of different clients use the same hardware at large scale, which is the key to the efficiency that cloud computing provides, any breakdowns or hacks could prove devastating to many. “Today you have these huge, mammoth cloud providers with thousands and thousands of companies cohosted in them,” says Radu Sion, a computer scientist at the State University of New York at Stony Brook. “If you don’t have everybody using the cloud, you can’t have a cheap service. But when you have everybody using the clouds, you have all these security issues that you have to solve suddenly.”
Cloud computing actually poses several separate but related security risks. Not only could stored data be stolen by hackers or lost to breakdowns, but a cloud provider might mishandle data–or be forced to give it up in response to a subpoena. And it’s clear enough that such security breaches are not just the stuff of academic experiments. In 2008, a single corrupted bit in messages between servers used by Amazon’s Simple Storage Service (S3), which provides online data storage by the gigabyte, forced the system to shut down for several hours. In early 2009, a hacker who correctly guessed the answer to a Twitter employee’s personal e-mail security question was able to grab all the documents in the Google Apps account the employee used. (The hacker gleefully sent some to the news media.) Then a bug compromised the sharing restrictions placed on some users’ documents in Google Docs. Distinctions were erased; anyone with whom you shared document access could also see documents you shared with anyone else.
Andin October, a million T-Mobile Sidekick smart phones lost data after a server failure at Danger, a subsidiary of Microsoft that provided the storage. (Much of the data was later recovered.) Especially with applications delivered through public clouds, “the surface area of attack is very, very high,” says Peter Mell, leader of the cloud security team at the National Institute of Standards and Technology (NIST) in Gaithersburg, MD. “Every customer has access to every knob and widget in that application. If they have a single weakness, [an attacker may] have access to all the data.”
3. As the victim hired new VMs to handle the extra demand, the attacker also hired VMs. By checking IP addresses, the researchers found that the victims and attackers wound up on the same Amazon servers 40 percent of the time.
To all this, the general response of the cloud industry is: clouds are more secure than whatever you’re using now. Eran Feigenbaum, director of security for Google Apps, says cloud providers can keep ahead of security threatsmuch more effectively than millions of individuals and thousands of companies running their own computers and server rooms. For all the hype over the Google Docs glitch, he points out, it affected less than .05 percent of documents that Google hosted. “One of the benefits of the cloud was the ability to react in a rapid, uniform manner to these people that were affected,” he says. “It was all corrected without users having to install any software, without any server maintenance.” Think about the ways security can be compromised in traditional settings, he adds: two-thirds of respondents to one survey admitted to having mislaid USB keys, many of them holding private company data; at least two million laptops were stolen in the United States in 2008; companies can take three to six months to install urgent security patches, often because of concern that the patches will trigger new glitches. “You can’t get 100 percent security and still manage usability,” he says. “If you want a perfectly secure system, take a computer, disconnect it from any external sources, don’t put it on a network, keep it away from windows. Lock it up in a safe.”
But not everyone is so sanguine. At a computer security conference last spring, John Chambers, the chairman of Cisco Systems, called cloud computing a “security nightmare” that “can’t be handled in traditional ways.” At the same event, Ron Rivest, the MIT computer scientist who coinvented the RSA public-key cryptography algorithm widely used in e-commerce, said that