The virus--known as MyDoom, Novarg and as aby different antivirus companies--arrives in an in-box with one of several different random subject lines, such as "Mail Delivery System," "Test" or "Mail Transaction Failed." The body of the e-mail contains an executable file and a statement such as: "The message contains Unicode characters and has been sent as a binary attachment."
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In one hour, Network Associates itself received 19,500 e-mails bearing the virus from 3,400 unique Internet addresses, Gullotto said. One large telecommunications company has already shut down its e-mail gateway to stop the virus.
Once the virus infects a Windows-running PC, it installs a program that allows the computer to be controlled remotely. The program primes the PC to send data to the SCO Group's Web server, starting Feb. 1, a virus researcher said on the condition of anonymity.
The SCO Group has incurred the wrath of the Linux community forthat important pieces of the open-source operating system are covered by SCO's Unix copyrights. IBM, Novell and other Linux backers the claims.
The company's Web site was slow to load on Monday afternoon, a SCO spokesperson acknowledged, but the site was still accessible from the World Wide Web.
SCO's Web site was taken offline by denial-of-service attacks , none of which had been initiated by a virus. In the past, the company has blamed Linux sympathizers for at least one of the attacks.
Antivirus companies were scrambling on Monday afternoon to learn more about the virus, which started spreading at about noon PST. The virus affects computers running Windows versions 95, 98, ME, NT, 2000 and XP.
"A lot of the information is encrypted, so we have to decrypt it," said Sharon Ruckman, a senior director of antivirus software maker Symantec's security response center. Symantec has had about 40 reports of the virus in the first hour, a high rate of submission, Ruckman said.
From the first experiments
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The virus installs a Windows program that opens up a "back door" in the system, allowing an attacker to upload additional programs onto the compromised device. The back door also enables an intruder to route his connection through the infected computer to hide the source of an attack.
The virus also copies itself to the Kazaa download directory on PCs, on which the file-sharing program is loaded. The virus camouflages itself, using one of seven file names, including Winamp5, RootkitXP, Officecrack and Nuke2004. Variations in the body text include: "The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment."
Early data indicated an epidemic several times the size of the, which caused widespread infections last summer, said Scott Petry, a vice president of engineering at e-mail service provider Postini.
Mail systems that remove executable files from e-mails can