She also would not disclose the volume of data stolen, but said the company decided it would be prudent to alert all of its users via its Web site.

The company advised users to change their passwords and reminded them to ignore e-mails they may get that purport to be from the company and that ask for password information or instruct the user to download anything.

Monster.com was also hit by hackers in mid-2007. At that time the hackers obtained log-in credentials for companies seeking employees and used them to access Monster.com's database of job seekers. An automated Trojan then transmitted the personal information to a rogue server. Monster.com users were then targeted with scams via the stolen e-mail addresses.

In addition, the Monster.com site was the subject of an attack that same year that inserted malicious code onto certain pages of the site, automatically downloading a virus onto computers that visited the pages.