Security company Trend Micro today released an advisory concerning TROJ_AGENT.ADNA, a new Trojan horse which attempts to remove a file usually placed inside Program Files, a folder created by Windows which usually stores the content needed by the installed applications.
According to the advisory, the infection affects most versions of Microsoft's operating system including Windows 98, ME, NT, 2000, XP and Server 2003. In addition to the Program Files removal, the Trojan also attempts to modify some registry entries which could change the way your firewall works and make it useless in front of other web attacks.