It isn't only applications that Android secures. The team also looked at bits of software that are common entry points for attackers. For example, Cannings says, the software that runs media, such as audio and video on a Web browser, is very complex and a common target. In Android, that software runs apart from the browser in a separate media server, so that if it is compromised, an attacker can't access the passwords and cookies stored in the browser.

Charlie Miller, a security researcher at Independent Security Evaluators who has found and reported several bugs in the Android platform, says that Google's technique of placing each application on an Android phone into a separate sandbox can certainly be effective. For example, Miller did find a bug in the software that Android used to play mp3s, but found that the access he gained with his exploit didn't allow him to attack other applications on the phone.

However, Miller thinks Google relies too heavily on this one method of protection. "It is a good security piece, but in my opinion, there should be more layers," he says. An attacker could find a bug in the operating system that allowed him to break through the walls between applications, which would make bugs in media software just as dangerous as before, he says.

Miller adds that systems such as the iPhone will stop unauthorized applications from executing code. Google's system, on the other hand, allows any type of code to run, which puts more tools in the hands of the attacker.

Finally, Miller says, "Google has this other obstacle: that they make the operating system, but they don't control the phone." The first time he spotted a bug in Android, Miller notified Google and the company patched the Android source code the same day. This solution, however, didn't protect phones already in use. "They were basically at the mercy of T-Mobile [which currently offers the Android phones for sale in the US] to roll the patch out and push it out to all the phones that were in the world," Miller says. While some vendors may be responsive to security concerns on their phones, he believes that others might never roll out patches at all.

Cannings says that when a bug is found, Google notifies its carriers--currently 32 companies in 21 countries--and works to provide them with test builds of its proposed solutions. When the carriers are satisfied, they push the fix out to their customers.

No product is ever truly secure, Cannings says, but Google is working to prepare Android for the malware attacks that will inevitably come as smartphones become more popular.