Online communities such as Myspace are becoming a major target for spyware creators, security company Webroot has warned.
The group says spyware infection rates have returned to 2004 peak levels as cyber criminals focus on new distribution channels such as social networking sites.
Spammers have also recognised the extra potential for profit from adding spyware programmes to their emails.
"We're finding that the social-networking sites like MySpace are turning out to be hotbeds for spyware," chief executive Dave Moll told MSNBC.
"People are creating multiple profiles, and the links on their sites will take you to sites that will either download or drive-by download adware and spyware."
While spyware infections of business have decreased, many younger web surfers are less careful about threats from malicious programmes, Moll said.
"They're not looking out for danger in quite the way that more skeptical adults do. Kids on MySpace and sites like it act as though they are in a safe youth-only environment, and as a result their behavior is less cautious, and that is something that is being preyed upon by all kinds of internet villains.
"And we think spyware creators will be the most aggressive in exploiting that."
Webroot says there are now 527,000 malicious sites on the web, an increase of 100,000 from a year earlier.
Concern over the issue recently led Google to begin issuing warnings to searchers if they attempt to visit sites containing malware.
Safety first, people.