Microsoft's Windows CE is "extremely vulnerable" to mobile malware, industry experts warned today.

A new report from Kaspersky Lab said that Windows CE is wide open because it has no restrictions on executable applications and their processes.

Once launched, a program can gain full access to any Windows CE operating system function, such as receiving or transmitting files, alog with phone and multimedia functions.

"Creating applications for Windows CE is easy," said Aleks Gostev, senior virus analyst at Kaspersky Lab.

Only four virus families currently target Windows CE, but Gostev warned that the potential of the operating system as an environment for malicious code should not be underestimated.

"The viruses currently in existence represent all the most dangerous types of malicious program: classic file viruses, email worms, backdoors and worms which are capable of moving from a handset to a desktop PC once connected," he said.

"Platforms based on Windows CE are growing in popularity and in a few years they may come to take the market share of mobile device operating systems, squeezing out Symbian."

The report goes on to note that Symbian is a more closed system than Windows CE, as it is harder and more expensive to create applications for the platform.

However, the architecture of Symbian Series 60 contains a range of "serious errors" that expose it to attack, according to Gostev.

Symbian allows any system application to be rewritten without explicit user consent, and some file formats mean that the system can become unstable and reboot itself.

"The level of application security is very similar to that of Windows CE. In other words, it does not exist," said Gostev.

"Once an application has penetrated the system, it can take total control of all functions of the phone."