Malware writers are increasingly using rootkit technology to hide their creations from security software, according to researchers at McAfee's AVERT Labs.

The number of incidents in which malware and adware-like applications used the stealth technology increased by more than 600 per cent over the past three years, the researchers found.

In the first quarter of 2006, the number of incidents increased almost 700 per cent year-over-year.

"Clearly we are seeing that stealth technologies, and rootkits specifically, are increasing at an alarming rate," said Stuart McClure, senior vice president for global threats at McAfee.

"This trend in malware evolution is creating hardier and ever more virulent strains of malware that will continue to threaten businesses and consumers alike."

McAfee blamed the rise of rootkits on the wide availability of information on how to create such technology, including commercial kits that take the effort out of malware creation.

Rootkit technology has traditionally been used to build a backdoor into a system, allowing easy access to a hacker.

But the technology is now being used to cloak files and processes from the user and from security software to prevent its detection and removal.

The most famous example of rootkit technology is the XCP anti-piracy application introduced last year by Sony BMG. 

The technology was intended to prevent illegal copying of music CDs, but posed a significant security risk to computers on which it was installed.