Net worms change form, threaten greater havoc

Another potential threat is a worm that spreads so slowly that no one notices it has even arrived, Wignall said. The worm might slowly build a large infection base, which could be activated in the future, he said on the sidelines of DefCon, a three-day gathering in Las Vegas that drew 5,000 security experts to the largest annual conference for Internet defence.

Worms are a more virulent form of computer virus because they seek out new computers to infect on their own rather than needing to piggyback on other programmes to propagate. Internet worms typically spread through E-mail programmes, like Melissa in 1999 and Love Letter in 2000, or through holes in software, like Code Red and Nimbda in 2001, which exploited flaws in Microsoft programmes. Another type of attack, so-called companion worms, could potentially carry other worms with them, Wignall predicted. ‘‘This would enable a worm to cross platforms,’’ from Windows to Unix, he said.

Another way worms could spread is through music sharing networks, through which individual computer users can exchange digital songs and other data. ‘‘You would have a worm which talks to other copies of the worm,’’ he said. Such worms could even update their own code across the network to make them resistant to anti-virus defenses, Wignall said. This would amount to a ‘‘decentralised infestation on the network,’’ akin to the science fiction scenario depicted in the recent Hollywood movie Terminator 3, which features Sky Net, a US military intelligence computer which burrows into and eventually takes over every computer connected to the Internet.(Reuters)