update.exe definition, relationships, removal:

update.exe is an executable file that starts a malicious process, launches certain parasite components or runs a destructive payload. It is installed and used by such computer parasites as adware AdvSearch. It is also related to other parasites such as adware AproposMedia, adware xxxtoolbar, adware Acceleration Soft, adware AdRoar, browser hijacker CoolWebSearch.msupdate, browser hijacker CoolWebSearch.sys, adware IEDriver, dialer NsUpdate Dialer, worm W32.Backdoor.Rado, worm W32.HLLW.Repsan, adware Wengs Hijacker, keylogger Japanese Key Logger, adware BookmarkExpress, trojan ForBot Trojan, Direct Connection, Myftu, Orbit, ActualNames, OrbitExplorer, Ssppyy and Dafet.

These threats can use update.exe for different purposes, as the file's functionality depends on a particular parasite it belongs to. You are highly advised to scan the system, delete executable update.exe and terminate all the processes it started.

Please note that the update.exe file actually may be a fully legitimate part of the operating system or legitimate software. Often parasites use files with unsuspicious names, but malicious functionality. You should always carefully check the file before deleting it. It may not be related with malware, but can be required by your essential programs to work properly.