The security company noted: "One of the methods is to hijack clients performing Windows Update. Three Flamer apps are involved in delivering the rogue update: SNACK, MUNCH, and GADGET."
SNACK tended to sniff out NetBIOS requests on LANs and would then imitate a Web Proxy Auto-Discovery Protocol (WPAD) server and feed a rogue configuration file (wpad.dat) to the local network, thereby effectively hijacking it and forcing traffic to redirect to the malware-infected machine, Symantec said.
MUNCH - a web server within the Flame code - would then chow down on the redirected traffic, including matching URLs for Microsoft's Windows Update software.
The final part of the puzzle was GADGET, a module which Symantec said provided a binary signed by the dodgy Terminal Services certificate via the MUNCH web server that fooled the system into believing that it was the genuine article from Microsoft.