Once installed, the Trojan reaches out to a number of other machines, looking to download five files: TROJ_AGENT.JVH, TROJ_AGENT.JVI, TROJ_AGENT.JVJ, TROJ_DORF.AA, and WORM_NUWAR.CQ. (Note that, as mentioned above, Nuwar has been spotted as an infection vector for the Trojan itself.) It also opens up a slew of UDP ports, looking to make covert peer-to-peer-style connections to various IP addresses.

Interesting side note: BitDefender describes Trojan.Peed.P as containing the same three files and targeting a specific UDP port, 7871, for peer-to-peer connection purposes. That Trojan also uses a romantic-type subject line, and the payload claims to be a greeting card. However, that program's behavior appears to be significantly more aggressive -- sifting through address books, infecting genuine executables and attempting to shut down antivirus programs as well as regedit and taskmgr.

What's the best defense?

If your e-mail filter is properly blocking inbound executables, you're fine -- as SANS's Mark Hofman puts it in his blog, "If you get a .exe in your inbox, something is seriously wrong with your inbound mail filter." In addition, antispam filters also appear to be stopping infected messages. If an infected file appears in your spam filter, it may be deleted with no further trouble.

If you're not filtering your e-mail or you find yourself cleaning up after someone who doesn't, user education is key: Never click on an executable file received in an e-mail, even if you think you know who sent it.