Increasing numbers of PC users are falling victim to rootkit infections, otherwise known as stealth malware, according latest statistics from malware research firm Prevx.

The statistics highlight a growing concern in terms of both the number of infected PCs and those housing silent rootkit infections.

During the month of October alone one in six of the 291,000 users who downloaded Prevx’s scanning software discovered active spyware or malware on their PCs, according to the company.

Rootkits often bury themselves via other computer infections and then modify the operating system of the infected PC, concealing themselves from both the user and popular PC security products.

When used maliciously rootkits can allow criminals to remotely monitor, record, modify, steal and transfer any information entered or stored on a user’s computer, disabling PC firewalls and evading traditional security products at will.

"The rise of the rootkits has begun," said Jacques Erasmus, director of malware research at Prevx.

"Consumers and businesses now have a significant new threat to security and privacy to worry about. Rootkits are often undetectable and extremely difficult to remove. Both detection and removal are well beyond the capabilities of traditional Antivirus, Anti-spyware and so called Internet Security Suites."