A new Internet worm that spread through Asia, Australia and Europe on Monday is expected to take hold in the United States on Tuesday as people go back to work after the Martin Luther King Jr. holiday.
The "Bagle" or "Beagle" worm arrives as an attachment to an e-mail with the subject line "Hi" and "test : )" in the body text. The worm is activated when a user clicks on the attached file.
Once the attachment is opened, the worm tries to send copies of itself to all of the e-mail addresses that it finds on the victim's computer, faking the return address with one randomly generated from those sifted from the infected PC. It also installs a program that lets attackers connect to infected machines, install malicious software or steal files.
The worm probably is the precursor to more evolved versions that could wreak havoc with small business and home Internet users, computer security experts said.
Carey Nachenberg, chief architect of Symantec Research Labs in Cupertino, Calif., said he expects the worm to continue its rapid spread as more Americans begin sorting through the e-mail that piled up in their in-boxes following the three-day weekend.
"This is coming on hard and fast, and that's usually a bad sign going into a shortened work week," Nachenberg said.
Bagle has spread to computers in more than 100 countries, according to MessageLabs, an e-mail security company in New York City.
FBI officials did not return telephone calls seeking comment on whether law enforcement authorities are investigating the worm's origins.
Bagle also tries to download an unknown program from one of more than 30 Web sites located mostly in Germany and Russia. None of those Web sites was reachable as of Monday afternoon.
A German Internet service provider that hosted one of the Web sites recorded nearly 1 million different Internet addresses trying to connect to the site within a 24 hour period, indicating that as many as a million computers have been infected so far, said Tony Magallanez, a systems engineer for F-Secure Inc., in San Jose, Calif.