The Monster.com mess

The last thing you need when you're unemployed is a bank account that's suddenly emptied. But that's exactly what some unwary users of employment search site Monster.com faced after identity thieves made off with the personal information of more than a million people looking for jobs.

This still-developing story has enough nooks and crannies to confuse a gumshoe, but some facts are clear: Monster's resume database was looted, and the personal information taken was used to forge convincing messages that deposited password-stealing Trojans and ransomware on users' PCs.

Calculated and ambitious, the attack is striking for how it blended several elements -- stolen credentials of legitimate users, phishing e-mails, Trojan horses, money mules, and more -- into a slick assault. Here's what we know so far.

Was Monster.com hacked? No, as Symantec said immediately. Instead, the attackers accessed the resume database with legitimate usernames and passwords, probably stolen from professional recruiters and human resources personnel who use the "Monster for employers" section of the site to look for job candidates. But it wasn't until Thursday that Monster.com admitted as much. "By gaining unauthorized access to employer accounts, the software was obtaining job seeker contact information," a new alert said.

What was snatched from the database? Names, e-mail addresses, mailing addresses, phone numbers, and resume IDs, said Symantec. Yesterday, Monster.com added that only about 5,000 of the people whose data was filched live outside the United States. That squares with what Symantec's Amado Hidalgo said in an e-mail: The information-stealing Trojan was hard-coded to dig through only the "hiring.monster.com" and "recruiter.monster.com" domains, limiting their theft to the Monster USA site's database. "They only targeted the U.S. Monster site and not any other international Monster [Worldwide] Inc. sites, such as those in the U.K., Spain, etc.," said Hidalgo.

How was the information stolen? The Infostealer.Monstres Trojan runs batch searches by sending HTTP commands to the Monster Web site to navigate through folders, said Hidalgo. The malware then parses the output that appears in a pop-up window that holds the job seeker profiles that match the search criteria. Essentially, the Trojan worked as an automated search bot that located candidates, captured their contact information, and sent it to a remote server controlled by the criminals. Symantec said that the server, though located in Russia, was hosted by a company out of the Ukraine.

By using Infostealer.Monstres to do their harvesting, the attackers also covered their tracks -- the Trojan could be planted on any computer previously compromised, with the search seemingly originating with that computer's owner -- and could easily spread the work out among a number of IP addresses, probably to slip under any Monster radar potentially watching for unusually large numbers of search requests coming from any one location. (There is no evidence at the moment that Monster deploys such radar.)