It is usually spread via exploit kits (drive-by-downloads), phishing schemes, and social media, but Trend Micro researchers have recently spotted a variant that employs another propagation vector: removable drives.
In this particular instance, the malware variant is initially delivered via a malicious PDF file disguised as a sales invoice document.
Potential victims that attempt to open the file with Adobe Reader are faced with a notice that says that it can't be opened because "use of extended features is no longer available."
But in the background, the malware has already been silently dropped onto the system and run.
It first contacts its C&C center to download an updated copy of itself (if there is one available), but immediately after it checks whether removable drives are connected with the computer, and if there are, it drops a copy of itself in a hidden folder, then creates a shortcut to it.