A new variant of the Bredolab Trojan horse is attached to a fake "Facebook Password Reset Confirmation" e-mail, security firm MX Labs is reporting.

Some users are receiving the e-mail from "The Facebook Team," according to the security firm. The sender's e-mail address displays "service@facebook.com." In reality, the address and sender were spoofed.

MX Labs found that the e-mail was accompanied by an attachment named, "Facebook_Password_4cf91.zip and includes the file Facebook_Password_4cf91.exe" that, the e-mail claims, contains the user's new Facebook password. The security firm said that the element between the underscore and .zip are randomly chosen letters and numbers for each recipient.

When a user downloads the file, it could wreak havoc on their computer. MX Labs said in a blog post that the Trojan horse Bredolab "executes files from the Internet, such as rogue anti-spyware. To bypass firewalls, it injects its own code into legitimate processes svchost.exe and explorer.exe. Bredolab contains anti-sandbox code (the trojan might quit itself when an external program investigates its actions)." In other words, it's nasty.

Once it makes its way to the user's PC, Bredolab creates "%AppData%\wiaservg.log" and "%Programs%\Startup\isqsys32.exe" in the user's system files. MX Labs said that it also creates two new processes, called "isqsys32.exe" and "svchost.exe."