From WSJ.com - Dueling Hackers Hit Firms' Computers

WSJ.com - Dueling Hackers Hit Firms' Computers: "At least six worms have appeared in the past few days, taking advantage of one of the Windows' vulnerabilities announced by Microsoft last week. The speed with which the vulnerability has been exploited highlights the challenges facing computer network administrators, as they race to patch systems before hackers can take advantage of newly disclosed holes.
A first round of attacks that began Sunday had appeared to abate by Monday. Yesterday, an apparently separate group launched a more aggressive attack, scanning the entire Internet to search for unpatched systems. The new worm was spreading at a rate of one new machine a second, or 30 times faster than the earlier round, according to David Maynor, a security researcher at Internet Security Systems Inc. in Atlanta.
Once a machine became infected, it received additional instructions from a central server via an Internet-messaging system before attempting to infect additional machines on its corporate network, he said. Hackers have been organizing such infected machines into 'bot' networks that can be used to launch extortion schemes, spam or 'phishing' attacks, which seek to trick users into providing personal information."