T-Mobile G1 users may not need antivirus software, despite reports of security flaws in Google's Android operating system.

The news comes as antivirus developer SMobile released software to protect owners of the handset, which is based on the Android platform.

Even though Android is open source, it is unlikely to be more susceptible to malware than other, proprietary mobile operating systems, said Charlie Miller, principal analyst at Independent Security Evaluators and the researcher who found the first Android vulnerability.

While a developer could write a harmful application and distribute it via the Android Market, Google has put up some roadblocks that would make it hard for malware to cause much harm, Miller said.

"If you want to do anything dangerous like access personal contacts, you have to specifically say to the virtual machine 'these are things I'm going to have to do', and the virtual machine will ask the user if that's OK," he said.

Google Android applications run in a Java virtual machine on the phone. For example, if a user downloads a Scrabble game containing malicious code that tries to gather information from a user's email account, the phone will ask the user to approve the application's access to the email account. In that case, the user would decline the download, realising that a Scrabble game shouldn't need to read from an email account, he said.

Last week, however, hackers discovered a way to install applications natively on the phone instead of using the virtual machine. The capability could open doors to new security threats by letting applications access any phone function. Google said it has developed a fix for the bug and plans to push it out to users soon.

That is the second vulnerability to be discovered in as many weeks. The first, discovered by Miller, resulted from Google using outdated open-source code that didn't include an update already issued that closed the hole. But such vulnerabilities aren't unique to Android or open-source software.

"The fact is, you could do that against the iPhone or against the BlackBerry or whatever. All these phones have issues," he said.

SMobile argues that because Android is open source, it will attract more hackers who will be able to look for holes they can exploit to gather user data for malicious purposes.

NEXT PAGE: Only a few mobile viruses have appeared so far

T-Mobile G1 users may not need antivirus software says one security researcher.

While companies including McAfee, Symantec and F-Secure make smartphone antivirus software, although not yet for Android, only a few mobile viruses have appeared, and those haven't spread very far. That's partly because of the wide variety of operating systems that run mobile phones. A virus written for one operating system doesn't spread widely because it won't work on phones running different operating systems.

In addition, people generally don't use their phones to access or send the same kind of important data that they do on their PCs, making phones less-interesting targets for people looking to steal that information. Mobile commerce, for example, is a very small market, so few people enter their credit card numbers into their phones.

Miller said that if people are worried about security on their phones, software from providers like SMobile might let them rest easier, although he probably wouldn't bother to buy such software for himself.

While Google or mobile service providers are sure to patch holes or issue fixes to known problems, SMobile could potentially do so faster. Miller says he notified Google of the vulnerability he discovered on October 20. Google and T-Mobile began sending out a patch on October 31.

SMobile said its software will scan the G1 for more than 400 types of mobile malware, including viruses, worms and Trojans that can spread between mobile phones via the memory card. If new types of malware appear, SMobile's software will detect it and provide "timely" updates for users, it said.

Android users can buy VirusGuard for Android direct from SMobile for $10 (£6). Once the Android Market begins allowing developers to charge for applications, the software will be available there, SMobile said.