The search engine Google has achieved such ubiquity that it's already become a verb. Who hasn't googled an old friend, high-school flame, or job applicant? But its success has a dark side: It has become a chief source of information for hackers and virus writers who have learned how to use the search engine to dig up information that Web sites did not intend to make public. Johnny Long, a security expert and ethical hacker with Computer Sciences Corporation, recently released The Google Hacker's Guide: Understanding and Defending Against the Google Hacker to instruct the security community in the ways that Google is being used as a hacking tool. A paper by security company Imperva titled Web Application Worms: Myth or Reality? gives this practice another name: war searching.