NEW YORK -- Internet users worried about spyware and adware are shunning specific websites, avoiding file-sharing networks, even switching browsers.
Many have also stopped opening e-mail attachments without first making sure they are safe, the Pew Internet and American Life Project said in a study issued yesterday.
''People are scaling back on some Internet activities," said Susannah Fox, the study's main author. ''People are feeling less adventurous, less free to do whatever they want to do online."
Like no other Internet threat before it, spyware is getting people's attention, she said. ''It maybe will bring more awareness of all kinds of security issues."
Linda Parra, a technology usability consultant at an insurance firm in Madison, Wis., is typical of the once-burned, now-vigilant crowd. Hit twice by spyware, after which all her Internet searches went to a rogue search engine rather than Google, she bought the safer Mac computer, installed two layers of firewalls, and began switching off her broadband-connected machine when she's out.
''I've become a lot more security conscious," she said, adding that she had to learn much more about how computers and the Internet work. Parra also banned her daughters from game sites.
''All it takes is one click . . . and you can end up going somewhere you don't want to go and getting a little bonus pack [spyware] with your freebie," she said. ''I believe that's what happened."
According to Pew, 48 percent of adult Internet users in the United States have stopped visiting specific websites that they fear might be harboring unwanted programs. Twenty-five percent stopped using file-sharing software, which often comes bundled with programs to display ads that subsidize its development. Rogue programs can also disguise themselves as songs or movie files awaiting download on file-sharing networks.
Eighteen percent of US adult Internet users have started using Mozilla Firefox or another alternative Web browser. Many unwanted programs sneak in through security flaws in the dominant browser on Windows computers, Microsoft Corp.'s Internet Explorer.
In addition, 81 percent have become more cautious about e-mail attachments, a common way for spreading viruses, though rare for spyware or adware.
All told, 91 percent have made at least one behavioral change.