Narrator: This is Science Today. Many of us now have cell phones that feature a system called multimedia message service, or MMS. It's the next generation of text messaging and it allows users to receive images, audio, video and rich text. But there's a weakness in the MMS system that could be the target of a stealth attack. Computer scientist Hao Chen of the University of California, Davis demonstrated that this vulnerability can be exploited to drain people's cell phone batteries.

Chen: What we do is, just before your phone is about to enter the standby mode, we deliver a packet that is a piece of data to your cell phone. This would prevent your cell phone from ever entering the standby mode.

Narrator: Chen says bad guys can easily obtain a large hit list of vulnerable cell phone numbers and use a computer to launch the attack, silently sending these packets of information to drain batteries.

Chen: That would prove to be very bad in certain situations, such as emergency response and rescue.

Narrator: By demonstrating this weakness, companies and researchers can now come up with ways to foil such attacks. For Science Today, I'm Larissa Branin .