Organizations are finding it difficult to prioritize defense strategies against cyberattacks because most of them do not have an Internet-wide view of the attacks, according to a report from SANS Institute, the security training organization.

As a result, two security risks--Web applications and phishing--carry the greatest potential for damage, even though users instead tend to concentrate on less-critical risks.

The report, published by security training organization SANS Institute, amalgamates global data from security attacks on computers from March to August.

It identifies two main defense priorities for enterprise users. The first is targeted e-mail attacks, or spear phishing, that exploit client-side vulnerabilities in programs such as Adobe Systems' PDF Reader and Flash, Apple's QuickTime, and Microsoft's Office. These applications are described as the "primary initial infection vector used to compromise computers that have Internet access" and are the result of attackers taking advantage of "programming errors that are not being picked up by common vulnerability scanners."

The second priority is vulnerable sites. More than 60 percent of attacks are against Web applications and "convert trusted Web sites into malicious Web sites serving content that contains client-side exploits" by exploiting the most common vulnerabilities such as SQL injection and cross-site scripting flaws, in both open-source and custom-built applications. Such vulnerabilities make up more than 80 percent of attack opportunities.

A further finding is that applications are now more vulnerable and see more exploitation attacks than operating systems. There were no new major operating system worms seen in the wild during the reporting period.

Additionally, the report found there has been a "significant increase" over the past three years in the number of people discovering zero-day vulnerabilities: flaws that become known to attackers before they are discovered by security researchers, opening the chance of an attack against which no preparation has been made.

"This report is different from anything we have done before," a SANS spokesman said, "because it reflects massive amounts of data on the actual attacks (millions of them) and on the speed with which the underlying vulnerabilities are being patched (actual data from thousands of companies)."

The report sources includes attack data from 6,000 organizations, compiled by security hardware vendor TippingPoint, vulnerability data from 9 million computers compiled by security software vendor Qualys, and additional analysis and tutorial by the Internet Storm Center and SANS faculty members.