Digital worms wreak havoc at companies across US

A handful of digital worms that exploit vulnerabilities in some Microsoft Windows computers spread on Tuesday, hindering Internet access at some major companies.

The worms, called Zotob and Rbot, and variants of them, started emerging Saturday, computer security specialists said, and continued to propagate as corporate networks came to life at the beginning of the week.

David Cole, director of the security response unit for the Symantec Corp, which makes anti-virus software, said a growing number of worm writers apparently tried to exploit Microsoft's vulnerability after it was discovered.

The phenomenon of worm and virus creators turning en masse to a new vulnerability is increasingly common.

"It's pretty indicative of what we've seen recently," Cole said.

In this case, Cole said, the worm writers were not necessarily trying to outdo one another but were simply trying to apply their own creative twists and expertise to a known vulnerability.

Some corporations, including the New York Times Co, temporarily took some computers off the Internet and installed security patches to protect computers.

Among those hit was CNN, which reported that hundreds of computers were brought down late Tuesday afternoon in Atlanta and New York.