The website for the New York Times was hit by malicious adverts over the weekend.

A note was posted to the home page on Sunday that warned of a pop-up message warning users that their computer had been infected, and urging them to install fake anti-virus software.

The website also posted a Twitter update that instructed users to ‘not click on pop-up box warning about a virus' as it was ‘an unauthorised ad we are working to eliminate'.

Graham Cluley, senior technology consultant at Sophos, claimed that as many media organisations leave the delivery and creation of web adverts to third-party networks, they are effectively relying on other companies to deliver an unpolluted stream to their readers.

Cluley said: “Newspapers like The New York Times therefore still have a responsibility to warn their readers and clean-up their ads if a problem is discovered - but I think it's asking too much and impractical to think they should examine every advert in advance. After all, they're just plugging a small piece of JavaScript onto their website that collects the next advert from their provider's database.

“It is the advertising network that should be screening adverts to hunt for malicious content, higher up the stream. It is the responsibility of the webmasters at the media organisations not to do business with ad suppliers who can't manage this problem properly.”

 

Rik Ferguson, senior security advisor at Trend Micro, said: “The malicious software being punted in this case, is the same as we were seeing in much of the black-hat SEO around the 9/11 attacks.

 

“In this particular example, the malicious site and software is being hosted by a German provider, Hetzner AG, which has a colourful track record when it comes to spewing dodgy content, having hosted literally hundreds of malicious URLS.

 

“Here's a really simple tip to remember. If you ever see a pop-up window that arrives uninvited, telling you your PC is infected, ignore it, it is a scam. Close the window, empty your browser cache and to be on the safe side, run a real scanner. To be more fully protected in future, make sure you install an anti-malware program that will also block malicious URLs, rather than simply looking for malicious files.”