Monster.com, the popular online job-hunting site, is reporting another major breach of its user database -- the third time it has disclosed such a breach in the past two years.

In a warning issued to users on Friday, Monster.com stated that its "database was illegally accessed and certain contact and account data were taken, including Monster user IDs and passwords, email addresses, names, phone numbers, and some basic demographic data." The stolen data did not include resumes, the company said.

The warning does not offer any details on how the breach occurred or how it was discovered. However, it does say the company will be requiring users to change their passwords in the near future, and recommends that they change them proactively right away.

The warning also cautions users not to be taken in by phishing attacks that purport to be from Monster.com, stating that the company will never use email to ask for users' personal information or to offer software downloads.

Monster.com suffered another major security breach in August 2007, when a Trojan was found to have collected some 1.6 million pieces of information from the jobs site, potentially affecting hundreds of thousands of job seekers. The incident touched off a wave of security measures among employers as well as job hunters, with both groups seeking to eliminate personal data from online resumes and other documents that might be harvested by cybercriminals via the Web.

Monster.com made a number of changes to its system security following the Trojan attack, but barely two months later fell victim again when hackers hijacked some of its listings and used them to infect users with malware.

"We continue to devote significant resources to ensure Monster has appropriate security controls in place to protect our infrastructure, and while no company can completely prevent unauthorized access to data, Monster believes that by reaching out to job seekers, the company can help users better defend themselves against similar attacks," said Patrick Manzo, senior vice president and global chief privacy officer at Monster Worldwide, in Friday's warning message.

Friday's breach announcement resulted in downstream warnings from other job sites that use Monster.com, including this one from USAJobs.

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