Cybercriminals have bombarded inboxes around the world with what purports to be a contract but in reality delivers fake antivirus alerts on unsuspecting users' screens.

The email messages, which claim to come from "LSM Company" and have the subject line "Contact of Settlements," have continued to arrive in inboxes since Friday, throughout the weekend, and into Monday.

Recipients are told that if they agree to the terms of the contract, then they should expect "payment on Friday for the first consignment."

Attached to the email is a password-protected ZIP file, contract_1.zip, which contains inside it a malicious program called contract_1.exe.

Running the program will install the Troj/Agent-LNW fake antivirus onto the victim's computer.

Clearly the hackers thought that password-protecting the ZIP file would help their attack waltz past the defenses users have in place to protect their email. Although some antivirus and anti-spam filters might have trouble dealing with this kind of disguise, others can handle it in their stride.

As always, users would be wise to remember that curiosity killed the cat -- and be extremely wary of opening unsolicited attachments sent to them out of the blue.

This latest attack wave echoes some we saw late in 2008, many of which used the names of well-known companies as an extra temptation for users to open them.

Graham Cluley is senior technology consultant at Sophos, and has been working in the computer security field since the early 1990s. When he's not updating his other blog on the Sophos website, you can find him on Twitter at @gcluley. Special to Dark Reading.