Contact and account details were lost, including user IDs, passwords, email addresses, names, phone numbers, and basic demographic data. Fortunately, the breach did not include sensitive details like social security numbers or personal financial data.
Upon learning of the theft, Monster initiated an investigation and took active steps to correct the problem with the help of law enforcement. So far, the company claimed that it has not seen any misuse of the stolen information.
However, Monster users may soon be required to change their passwords upon logging onto the site, and it was also recommended that they proactively changed it in the meantime.
Monster decided not to send email notifications to avoid the risk that the messages would be used a template for phishing emails targeting job seekers. It warned users not to accept unsolicited emails asking for a Monster username and password.
Security experts have said that users should be aware that the information taken from Monster alone was not enough to attack bank accounts, but that it was nevertheless a very worrying breach of security.
Jay Heiser, Gartner research vice president, said: "It is the case that the criminal community is hoovering up large amounts of personal info and correlating it, functioning as some sort of underground information bureau."
He added: "The fact that most people do use the same password on multiple sites means it is possible for that password information from Monster to be available to attackers, along with information from other sources, to attack bank accounts."
He also said that users should never assume that a Software as a Service (SaaS) offering was safe, unless they were given evidence that it was. He said that consumers had no way of knowing how safe a site was, and shouldn't put anything on it that would harm them if it was stolen.
Heiser also said that this should serve as a warning to businesses. He said: "If what you do involves information that you can't afford to lose, or you don't want stolen, then you need to be given evidence by the service provider that they are taking security into account."
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