Job search giant Monster.com quietly disclosed this week that its user database was illegally accessed, resulting in the theft of an unspecified number of Monster user IDs and passwords, names, phone numbers and e-mail addresses. The company said it opted not to notify users by e-mail out of concern that those messages would be “used as a template for phishing e-mails targeting our job seekers and customers.” “We believe placing a security notice on our site is the safest and most effective way to reach the broadest audience,” the company said in a statement posted on its homepage. “As an additional precaution, we will be making mandatory password changes on our site.” In 2007, a Trojan horse program that anti-virus giant Symantec Corp. named Infostealer.Monstres began using hijacked Monster.com employer accounts to hoover up data on Monster.com users, ultimately gathering information on roughly 1.6 million users. Not long after that,