Viruses Find New Ways to Worm into Computers
Just when you thought you knew a computer virus or worm when you saw one, several new infections that may fool you are gaining momentum on the Internet.
Most e-mail viruses require the victim to double-click open an infected attachment before they can wreak their havoc. But Badtrans-B and Atiz, two worms that were spreading quickly over the weekend and Monday, can launch themselves automatically when the recipient views or even just clicks on the subject line of an infected e-mail message using Microsoft's Outlook and Outlook Express programs. October's Nimda virus used a similar technique, which helped it spread further and faster than it otherwise might have. Computer users were safe from viruses as long as they didn't download programs from the Internet or open e-mail attachments. But these days, viruses are as capable of getting into computers as Santa Claus is at getting down chimneys.
Antivirus software maker McAfee, a division of Santa Clara, Calif.'s Network Associates, upgraded Badtrans-B to a high-risk virus for consumers. Vincent Gullotto, director of McAfee's virus lab, said the worm is infecting more home users than corporate networks.
To prevent these and other viruses from automatically launching themselves, Gullotto advised down loading a software patch from Microsoft at www. microsoft, com.
Badtrans-B and Aliz have shown up with many different subject lines, ranging from the low key "info" to "Fw: Funky pictures -- check it."
Meanwhile, a worm called SirCam is still popping up regularly in e-mail boxes, months after it was first discovered. SirCam takes a Microsoft Word document from an infected computer and e-mails it out with a message reading "I send you this file in order to have your advice."
Gullotto attributed SirCam's staying power to social engineering. SirCam takes the title of the Word file as its subject line, which means the virus might arrive labeled anything from "blJsiness plan" to "diary." It is those sometimes-intriguing subject lines that entice people to open SirCam-laden attachments and spread the virus, Gullotto said.
To protect against all of these viruses, experts advise that computer users install antivirus software and regularly update it from the company's Web site.
What does the author means by saying "gaining momentum on the Internet"？

A. becoming more and more serious.
B. being the most important moment.
C. having the bigger and bigger impetus.
D. gaining more velocity and weight.