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Wireless worms will follow influenza’s example

It's not just the flu that will thrives aboard a busy flight or within a hectic workplace – computer worms could spread in similar way

It’s not just the flu that thrives aboard a busy flight or within a hectic workplace. Computer worms could spread in remarkably similar fashion, according to a new mathematical model.

Several proof-of-concept worms have been created and two, Cabir and Commwarrior, successfully spread in the “wild†although not very efficiently.

Nonetheless, as portable devices become more fully functional, the risk of a full-blown outbreak is only likely to increase, which makes modelling an outbreak important to devising countermeasures.

, an expert on infectious diseases at Imperial College London and , a researcher at BT’s research lab in Suffolk, UK, created a mathematical model to better understand the way a wireless computer worm would spread between portable devices.

Flu-like spread

In December 2007, another researcher, Steven Myers, at Indiana University, US, developed a model to show how a wireless computer worm might spread between stationary Wi-Fi routers.

The new model adds another dimension by factoring in the movement of people carrying infected or vulnerable devices.

Rhodes and Nekovee’s model considers a crowd of people carrying Bluetooth-enabled smartphones, each with a fixed range for connecting to other phones in the crowd.

Members of the crowd move in a straight line, and at a fixed speed. If a phone is infected with a worm it then has a fixed probability of infecting other devices while they are within range.

The work shows that the spread of a wireless worm can be represented using a common tool for representing virus outbreaks, called a standard mass-action mixing model. “The transmission model is actually very similar to something like influenza,†Rhodes told 51¶¯Âþ.

‘Surgical mask’

This means, just like a real virus, a wireless worm would spread most efficiently in a busy setting and could also hop between geographically distant locations, for example aboard a plane.

“A Bluetooth worm’s ability to spread is rooted in person-to-person contact,†says , a chief researcher at Symantec Security Response in the US. So a mass-action mixing model provides a good approximation.

“Knowledge that person-to-person contact, or rather device to device contact, represents a major factor in how a Bluetooth worm spreads is definitely important,†Chien adds.

He also suggests that a simple mitigation strategy would be to disable non-essential Bluetooth communications during an outbreak: “This reduces the contact occurrences and would be analogous to wearing a surgical mask in areas of potential infection.â€

Bruce Schneier of security company describes the work as “great and interesting reserach.â€

“What’s interesting is that malware depends a lot on the characteristics of the underlying network,†he says. “The phone network is different [to existing networks] and the spreading characteristics will be different.â€

However, he doubts whether it will lead to any radically new strategies for defending against such threats. “People subscribe to automatic update, because worms spread faster,†he says. “Fast spreading is a characteristic of wireless worms, too.â€

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