http://www.v3.co.uk/v3-uk/news/2097558/quarters-rootkit-infections-windows-xp-machines
anti-virus software vendor Avast.
http://www.zdnet.com/blog/security/study-rootkits-target-pirated-copies-of-windows-xp/9223?tag=nl.e539
The Czech firm's Virus Lab researchers analysed over 630,000 samples from a six-month study, and found 74 per cent of infections originating from Windows XP machines, compared to 17 per cent from Vista and only 12 per cent from Windows 7.
http://www.theinquirer.net/inquirer/news/2097673/rootkit-infections-windows-xp
Three out of four rootkit infections are on Windows XP
Report is not good news for the Microsoft OS
FREEMIUM antivirus vendor Avast warns that unpatched Windows XP machines continue to pose a serious threat to the internet ecosystem by harbouring three quarters of all rootkit infections.
The company has an unique insight into the threat landscape thanks to over 130 million active Avast! antivirus installations worldwide that send it malware telemetry. According to a recent analysis performed by the firm's researchers, 74 per cent of 630,000 rootkit samples found in the wild originated from Windows XP machines.
This rootkit infection rate is almost two times higher than the decade-old operating system's global usage share of 38 per cent. Avast's statistics show that 49 per cent of its customers have XP running on their computers.
The numbers clearly show that the high Windows XP infection count can't simply be explained by its market share. "One issue with Windows XP is the high number of pirated versions, especially as users are often unable to properly update them because the software can't be validated by the Microsoft update," said Przemyslaw Gmerek, Avast's leading rootkit expert.
Rootkits are serious threats because they function at the lowest levels of the operating system, which makes them hard to detect. For example, some rootkits hook the file system drivers to hide malicious files.