London, February 15: Microsoft experts in the UK are trying to develop friendly software “worms” capable of spreading between computers instead of being downloaded from central servers.

Milan Vojnovic, a researcher from Microsoft Research in Cambridge, says that software patches that spread like worms may be faster and easier to distribute because no central server will then have to bear the entire load.

"These strategies can minimise the amount of global traffic across the network," New Scientist magazine quoted him as saying.

He says that most existing software worms, which randomly probe computers while looking for new hosts to infect, are inefficient because they waste time exploring groups or "subnets" of computers that contain few uninfected hosts.

Vojnovic believes that the ideal approach to improve the efficiency of the worms will be to use prior knowledge of the way uninfected computers are spread across different subnets.

The information will help reduce the possible number of probes by a worm, and thus enable it to focus its attention on the most fruitful subnets by infecting a given proportion of a network.

Given the scant availability of perfect information in most cases, the researchers are also thinking of equipping software patches with the ability to learn from experience.

The researchers plan to achieve this by using a more targeted approach wherein a worm contacts other computers only in the same subnet, and keeps spreading in the same subnet upon finding plenty of uninfected hosts there.

The worm will change its track just in case it does not find uninfected hosts, say the researchers.

"After it fails to reach new uninfected hosts a fixed number of times in a row, say 10, it moves on to find new groups using random sampling," says Vojnovic.

He insists that these strategies may also help defend against malicious types of worm.

"If we understand how future worms might be capable of spreading, we can design better countermeasures," says Vojnovic.

A paper on the Microsoft research will be presented at the 27th Conference on Computer Communications (INFOCOM) in Arizona, US, in April 2008. (ANI)