I know there's been a lot of conversation (all around the internet) about mobile viruses, but I haven't been able to find an answer to the following question:

Can a virus infect a symbian based mobile phone secretly (in cases where there is no antiviral software in use)? For example, if I browse the web with these newer mobile browsers, can a virus lurk on the website and infect the phone independently, so that I know nothing about the infection and there's no indication of anything being installed without my approval? Or if the user receives an infected MMS, can the infection be transferred to the phone even if the user refuses to install any software? So I mean cases where the user just, for example, browses the web, but doesn't install anything by himself.

Or what is more interesting, would it be even possible to build a virus like this for any Symbian platform? Is it technically possible for a virus to install itself without the permission of the user?

Of course, as a S60 3rd ed. user I'm mostly interested in it specifically, but all kinds of answers are welcome.

The answer to all those is no. A virus cannot infect a smartphone without the user actively allowing it to by clicking ok for a file to be transferred. If you never click ok for unauthorised files, you will never be infected.

S60 3rd Edition is so secure that AAS has stated several times there's no need for anti-virus software.

Smartphone virus stories in the press are almost all either misunderstandings or journalists trying to think up an exciting story, but there's no documented cases of viruses in the wild infecting smartphones in the way that they infect PCs. The only time they've been spread has been through deliberate hacking in labs.

Some smartphones have been infected in the wild because the user has been tricked into downloading a file that they thought was a pirated game or app, and it turns out to be just a virus, or an app that also contains a virus. They can't really complain about it to anyone because the download itself was illegal, it would be like a drug user complaining to the police about the quality of their drugs.

So smart use of smartphone is all that's needed. That's good to know.

Thanks for the answer!

Just one additional note, currently most (if not all) operating system codes are stored on the ROM. So it is read only. This makes difficult for the hackers to "hack" the OS (for example to allow installing malicious code in S60 3rd Edition).

Of course, there is a possibility to hack the OS and reflash the phone, but it is not that easy because they have to break several security layers.

I am also interested seeing how the hackers will break Platform Security. No platform is unbreakable.