Chinks have been found in the armor of new Vista software that Microsoft has touted as the safest operating system it ever designed, a computer security firm said. Determina Security Research, in Silicon Valley, said it notified Microsoft of half a dozen software vulnerabilities, including potential for hackers to take administrative control of computers.

"The vulnerable code is present in all versions of Windows up to and including Windows Vista," Determina warned in a security bulletin on its website.

A Russian programmer that also discovered the potential to exploit a Vista weakness to gain access to computer systems published the information on the Internet on December 15.

Microsoft is working to patch Vista, according to Determina. A business version of Vista was released in November and is to be available for the home computer market on January 30.

Hackers could invade Vista-based computers by sending booby trapped emails or tricking people into visiting websites that secretly plant malicious codes on their machines, according to Determina.

This is not the first report that arises security concerns about Windows Vista. IT security firm Sophos had also announced early December that three of the top ten worms are capable of bypassing the Vista's security defences.