Troj_Agent.QMN is a Trojan that may arrive bundled with malware packages as a malware component. It may be downloaded unknowingly by a user when visiting malicious Web sites.

When executed, it accesses a certain Web site to download and execute files. Trend Micro detects the said files as TROJ_AGENT.GUK and TSPY_LDPINCH.AKY. As a result, routines of the downloaded Trojan and spyware are also exhibited on the affected system.

Technical details can be found at this Trend Micro page.