After a prolonged absence, waves of Trojans distributed as Zipped email attachments have been showing up in our spam traps for a few weeks. The spam messages employ the same hackneyed shipping confirmation pretext as many previous iterations of this scam. This technique’s emergence as a common malware distribution method correlates with the emergence of Trojan-Downloader-Tacticlol.
The messages claim to come from various express shippers, including DHL, UPS, and FedEx, as well as one that may have originated in a malware guy’s imagination: Post Express. And even though the distribution method mimics those used by Tacticlol, the payloads haven’t been limited to that Trojan. This time around, the files belong to a wider variety of malware, including not only several new variants of Tacticlol but also Trojan-Downloader-Karagany, Trojan-Relayer-Highport, and SpyEye.
The Trojans’ icons look like Office documents or Acrobat PDFs, which serve to further convince victims that the file isn’t dangerous. The email attachments — Zip files with names such as tracking.zip, Post_Express_Label.zip or DHL_tracking.zip — aren’t dangerous unless you open the attachment, extract the Trojan, and execute it. But once you do, you’re in for a world of trouble.
