NEW YORK (CNNMoney.com) -- The majority of adults who use of social networking sites like News Corp.'s (Charts) MySpace and FaceBook engage in dangerous behavior that exposes them to cybercrime, according to a survey released Wednesday.

About 74 percent of adults who use social networking sites have given out personal information like an e-mail address, birthday or social security number, according to a survey conducted by security software firm CA (Charts) and the National Cyber Security Alliance (NCSA).

"Giving out a social security number, paired with a birthday and name could provide enough ammunition for criminals to hack into financial records and compromise users' personal information," Ron Texeria, executive director of NCSA, said in a statement.

Besides compromising their personal information, adults are also leaving their computers vulnerable to attacks. About 83 percent of the survey's respondents said they've downloaded files from other profiles.

And it isn't only personal computer networks at risk, as an estimated 46 percent of the respondents said they visit social networking sites when they're at work -- jeopardizing business networks.

All the major online sites like Yahoo (Charts), Google (Charts), Microsoft's (Charts) MSN and Time Warner's (Charts) AOL are aggressively pursuing social networks.

About 2,100 adults participated in the survey.

Is FaceBook worth a billion bucks?

Murdoch unveils MySpace ambitions

Protect your identity