More than 89% of security incidents went unreported in 2007, according to survey of about 300 attendees at this year's RSA Conference.

Security incidents, as defined by the study, represent "an unexpected activity that brought sudden risk to the organization and took one or more security personnel to address."

Some of the security incidents, such as the e-mail-borne malware and phishing that affected 69% of respondents' companies, may not have led to serious consequences in every instance. But 29% of those answering the survey said their organizations experienced customer or employee data leakage. Twenty-eight percent reported insider threats or theft and 16% reported intellectual property theft.

"With 29% of respondents stating that they experienced the leakage of employee or customer data in 2007, it is alarming to see that only 11% of those types of incidents went reported," said Tim Mather, chief security strategist for RSA Conference, in a statement. "Security professionals need to remain cognizant of the regulations that their organizations must comply with and ensure they are taking steps to properly report the security incidents that are required by law -- whatever they may be."

Such findings echo a recent a study of over 500 data breach forensic investigations conducted by Verizon Business Security Solutions. According to Bryan Sartin, VP of investigative response at Verizon, the publicly reported breaches are "just the tip of iceberg." He said that less than 5% of the more than 500 cases covered in the Verizon study involved some form of disclosure.

In short, companies appear to be far more insecure than they acknowledge. The RSA survey indicates that 46% of companies experienced no security incidents in 2007, 19% experienced 1 to 2, 14% experienced 3 to 5, 7% experienced 6 to 10, 3% experienced 11 to 20, and 13% experienced more than 20 security incidents.

The top security challenge, according to respondents, is lost or stolen devices (49%), followed by non-malicious employee error and employee education (tied at 47%), budgetary constraints (44%), external hacking threats (38%), executive buy-in (26%), and malicious insider threats (22%).