A new worm that uses a known security hole in Symantec's corporate antivirus tools to spread has hit the Net, experts warned Friday. <A HREF="http://news.zdnet.com/2100-1009_22-6144282.html?tag=nl.e550">The worm, dubbed Big Yellow</A> by eEye Digital Security, turns vulnerable computers into remote-controlled zombies. It is the second such malicious code in as many months that exploits a 6-month-old security flaw in Symantec Client Security and Symantec AntiVirus Corporate Edition. A fix for the flaw has been available since May.