Microsoft spokesman Jim Desler said Thursday that some Hotmail servers were brought offline to deal with the problem and that service was not disrupted. About 110 million people have accounts with the free Web-based email service, according to Microsoft.
The infection comes after a big push by the Redmond, Washington-based software giant to get customers to download a patch to protect their computers from the worm, which takes advantage of a security hole in the company's Web server software running on Windows NT and Windows 2000 systems.
Desler said he did not know how Microsoft itself had managed to fall victim to the virus. He said some Hotmail servers may have been replaced recently for some reason with servers that hadn't been patched yet.
Desler also said the company was still not sure which variant of the worm corrupted its servers. The original Code Red worm spawned a nastier sequel, Code Red II, which leaves an infected server with a "back door" that could be used by hackers to gain control of the server or gain access to the data it contains. Microsoft said no personal information had been breached as a result of the Hotmail infections.
"We continue to take this very seriously," Desler said. "This is a highly malicious worm, and we are taking extra steps to protect our servers from further attacks."
Also Thursday, shipping giant Federal Express said it suffered isolated server problems Wednesday that it attributed to the Code Red worm.
Spokeswoman Pam Roberson said the company has implemented a contingency plan and is working on cleansing its systems of the worm. She said the problems caused delivery delays in isolated areas of the United States on Wednesday but said things were running normally Thursday.
Code Red has contaminated hundreds of thousands of server systems around the world since its introduction last month. The original worm prompted the White House to move the address of its Web site when officials learned the site had been specifically targeted by Code Red. The worm also led to government warnings from the FBI before tapering off as a result of people applying the Microsoft patch.