Innocent companies' websites are being hacked to serve images of child sex abuse, the Internet Watch Foundation has warned.
The charity said that, in the past six weeks, it has received 227 reports of netizens being directed from completely legal online porno sites to web pages on a second server containing illegal material.
Typically, someone visiting a normal adult porn website is redirected to, say, a file directory listing in a furniture shop's online home, which has been compromised and filled with images of terrible abuse.
Such trickery - stashing highly illegal content on an innocent organisation's servers - makes a mockery of the UK government's attempts to filter out what it determines to be the murkier corners of the internet, and also puts visitors and site owners in legal danger: the defence "but I didn't know!" is not guaranteed to succeed if the unlucky netizen is subsequently charged with possession and making of indecent images.
“We hadn’t seen significant numbers of hacked websites for around two years, and then suddenly in June we started seeing this happening more and more," the foundation's technical researcher Sarah Smith said in a statement.
“It shows how someone, not looking for child sexual abuse images, can stumble across it. The original adult content the internet user is viewing is far removed from anything related to young people or children."
The charity - which acts as a hotline for reports of online child abuse - described the illegal content as some of worst of its kind, and said people had been very distressed by what they'd seen.
Surfers leafing through legal XXX sites click on an image or video there and be redirected to a folder containing the images on the hacked site, which might be a furniture store or other unrelated business site. Neither the administrators of the adult site nor those of the hacked site would be aware that the link and folder existed, IWF said.
"Our reporters have been extremely diligent in explaining exactly what happened, enabling our analysts to re-trace their steps and take action against the child sexual abuse images," Smith said.
“Since identifying this trend we’ve been tracking it and feeding into police forces and our sister hotlines abroad."
The foundation said that in all cases it had been able to get the sick material removed. ®