Viruses Without Borders

What if your smartphone could infect your laptop? Proof-of-concept code is out for malware that infects multiple operating system platforms simultaneously. This multiplatform -- or hybrid -- virus is typically aimed at both mobile devices and desktop machines.

Most malware today is written to attack a specific platform or application. But with mobile phones, PDAs, Bluetooth, and laptops, the standard tools of many users today, researchers say it's no surprise attackers would come up with ways to initiate an exploit that spans all of these platforms at once.

"The threat is real. There's proof-of-concept that multiplatform [viruses] do exist and some have been found in the wild," says Shane Coursen, senior technical consultant for Kaspersky Lab.

Mikko Hypponen, chief research officer for F-Secure, says so far his research team has only seen this malware in proof-of-concept code. "There's a real possibility of something more than proof-of-concept coming around the corner."

And so far, the good news is writers of this malware are more "old-school" hackers trying to win bragging rights for being the first to design such exploits rather than more profit-minded cybercriminals, Hypponen says.

The most popular of these is Mobler, a worm that F-Secure first discovered in late August. Mobler infects both Symbian Series 6 smartphones and Windows. Its dispersal requires physical effort on the user's part, however: The user would have to take a memory card from his smartphone and load it onto his PC to transfer photos or other apps, for instance. Mobler then would try to trick the user into clicking on a file that looks like a system folder icon, for example, to infect the PC, Hypponen says.

And this malware can continue propagating. "If you later stick another memory card from another phone onto that PC, it infects that phone, too," he adds.

This obviously wouldn't spread anything like an Internet worm since it relies on the user (unknowingly) physically moving it from device to device.

But if Bluetooth is in the picture, a multiplatform/hybrid virus could spread more readily. Hyponnen says, in the future, a laptop user with Bluetooth in a coffee shop could get hacked by an infected smartphone. "The infected phone could see you're a Bluetooth laptop and figure out you're running Windows [via the Bluetooth fingerprint] and send you a binary file," he says. "This wireless world we're living in will enable multiplatform viruses to jump" from one platform to another more easily.

The user would have to accept the file, of course, to get infected. But a little social engineering, Hyponnen says, goes a long way. These hybrid viruses are more difficult to write, too, and would have separate copies of the virus for each platform: "So when Mobler is running on a PC, the PC virus carries a copy of the Symbian virus," for example.

While these viruses are not a big problem yet today, security experts say to be on the lookout and to shore up user policies.

"It's not going to be a real serious threat until organized crime finds a way to make money with it," says Randy Abrams, director of technical education for Eset. "It's now a low-yield thing -- users are not transferring near the amount of money on smartphones as they are on PCs, so it's not yet attractive to go after from a financial standpoint."

— Kelly Jackson Higgins, Senior Editor, Dark Reading