External.exe is a mass-mailing worm W32.Mytob.EV@mm. External.exe tries to terminate antiviral programs installed on a user computer. External.exe opens a back door on TCP Port 8900. Related files: %System%\External.exe Adds the value: "External Dependencies" = "%System%\External.exe" to the Windows startup registry keys. More info: http://securityresponse.symantec.com/avc... Removal: Kill External.exe process and remove External.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.