Attack code for a new security hole in Excel has surfaced on the Internet, just as Microsoft is scrambling to respond to a separate bug in the spreadsheet program. The latest vulnerability could cause Excel to crash after a malicious file is opened, according to an alert Symantec sent to customers on Monday. The security company also said there was a risk that an intruder could commandeer a PC. "Attackers may also be able to execute arbitrary code…but this has not been confirmed," it said. The security hole exists because Excel fails to properly check user-supplied input before copying it...