What is it?
Winupdate.exe is a file associated with a virus called w32.Gaobot.BIA What does it do?
W32.gaobot.bia is a network-aware worm that spreads to remote network
shares, through backdoors opened by other common backdoor Trojan horse
programs, and by exploiting several Windows vulnerabilities. The worm
opens a backdoor and allows a remote attacker to have unauthorized
access to the infected computer. More information and removal instructions @symantec