WWW- [The Daily Mail]- Want to see naked pictures of your favourite Hollywood actresses? It could cost you an expensive trip to your local computer repair shop if you do.

Fake emails claiming to offer nude photographs of Angelina Jolie, Nicole Kidman, Natalie Portman, Milla Jovovich and pixelated videogame babe Lara Croft are behind 80 per cent of computer viruses last month, according to experts.

For, though claiming to contain shocking pictures of female celebrities, the emails, once opened, install a malicious rootkit.

“These emails are masquerading as pornographic content, tempting the unwary into opening a file on their Windows computer which will install a rootkit and download further malicious code from the internet,” said Graham Cluley, senior technology consultant for Sophos.

“This kind of social engineering trick is nothing new – in fact it has been used so often by cybercriminals that it sometimes feels like it’s been around since the days of the silent movies.

“However, that hasn’t stopped it from being an effective way to fool many people into running code designed to allow hackers to break into computers.

IT security and control firm Sophos is urging computer users to think before opening unsolicited email attachments following the widespread spam campaign.

The emails, which typically have an attached file called amazing.zip or shocking.zip, contain a message similar to:

Good morning, old chap!

Shocking video of nude Angelina Jolie. See it in your attachment.

Best Regards.

Mr Cluley said: “The best way to defend yourself is to practise safe computing. That means not only running an up-to-date anti-virus, security patches and firewall – but also exercising caution over what programs you decide to run on your computer.

“You should always think twice before opening a file that unexpectedly arrives in your email inbox.”

“Rootkits are software frequently used by third parties – usually a hacker – to hide other software and processes using advanced stealth techniques.

“Malicious code, such as spyware and keyloggers, can be invisibly cloaked from detection by conventional security products or the operating system making them hard to detect.

“Hackers use rootkit technology to maintain access to a compromised computer without the user’s knowledge, so it’s important to be properly defended from these sort of threats.”