Hackers are hitting paydirt in their search for browser bugs. According to Symantec's twice-yearly Internet Security Threat Report, hackers found 47 bugs in Mozilla's open-source browsers and 38 bugs in Internet Explorer (IE) during the first six months of this year. That's up significantly from the 17 Mozilla and 25 IE bugs found in the previous six months. Even Apple's Safari browser saw its bugs double, jumping from six in the last half of 2005 to 12 in the first half of 2006. Opera was the only browser tracked by Symantec that saw the number of vulnerabilities decline, but not by much. Opera bugs dropped from nine to seven during the period. And while Internet Explorer remained the most popular choice of attackers, no one is invulnerable. According to the report, 31 percent of attacks during the period targeted more than one browser, and 20 percent took aim at Mozilla's Firefox.