Recent studies have revealed that as much as one-third of the internet may be composed of pornographic webpages.  But other studies have cast doubts on the safety of those pages, warning that malware and other nasty surprises like dialers await porn visitors.

Those claims are a load of bullocks, though, says UK free-antivirus firm Avast.  The firm says that in a recent study it found 99 infected non-pornographic pages for every infected porn page.

They found that many seemingly "safe" sites, including sites of high profile businesses, have been compromised to include malicious attack scripts designed to take advantage of unpatched Windows flaws.  One high profile find was the smartphones section of the Vodafone UK website, which ran a Javascript to exploit unpatched Windows Help and Support Center flaw (CVE-2010-1885) and download malware to the users' computer.

At the time of release, the site sub-domain blackberry.vodafone.co.uk still contained malicious code, but the site from which the attack payload was to be downloaded from was no longer online.

Avast researcher Miloslav Korenko comments, "Users browsing Vodafone domain should be safe - until new hack/updated hack will be performed.  Of course, the Blackberry section of Vodafone.co.uk website needs to be cleaned as well - to prevent future attack similar to this one."

Similarly compromised business pages were frequently found elsewhere.  On a UK hotel site (http://kensington-london-hotels.co.uk), the blogs section was altered to run malicious scripts that would deliver malware payloads.  Other infected legitimate sites included Brazilian software download site Baixaki and a variety of small business websites in Germany.  One in five website infections are similar to Vodafone's -- using a script to attack an unpatched Windows flaw and deliver malware -- according to Avast.

In contrast with the multitude of infected non-pornographic sites, pornographic sites examined in the study actually demonstrated a remarkably low infection rate.  This is in line with the recent UK study that identified that while roughly a third of the internet was porn, only a small percentage of porn sites were unsafe.

Avast CTO Ondrej Vlcek states, "We are not recommending people to start searching for erotic content but the statistics are clear - for every infected adult domain we identify there are 99 others with perfectly legitimate content that are also infected."

Pornographic sites have long been scrutinized for possible attacks as in the early days of the internet they were a source of attacks, and still continue to be a promising candidate merely because of the vast amount of traffic passing through them. But now that browsers have become more wary and employed safer browsing practices when visiting such sites, malicious parties have increasingly taken to attack legitimate sites, it appears.