Troj_Dloader.UEF is a Trojan that may be downloaded from remote sites by other malware. It may be dropped by other malware. It may be downloaded unknowingly by a user when visiting malicious Web sites.

It creates folders. It drops copies of itself. It drops files/components.

This Trojan creates an entry in the registry to enable its automatic execution at every system startup.

It accesses Web sites to download file(s). It saves the downloaded files using certain file names. Trend Micro detects some of these files as TROJ_PAKES.LW and TROJ_AGENT.WGM. It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Technical details can be found at this Trend Micro page.