Allotting to Facebook, users were somehow tricked into copying and pasting malicious code into their browser bars. Hackers then gained access to their profiles and could post whatever they wished, and any of the user’s Facebook admirers could see the images.

Chester Wisniewski, a security researcher at Sophos, enounced like schemes in the past experience lured users in with promises of free or discounted products.

It was unclear Tuesday who was responsible. Groups of hackers get threatened to posed away a virus to “take down Facebook” over their concerns with the style it handles user privacy.

Daimon Geopfert, a security expert for RSM McGladrey, said that this was one of the largest Facebook attacks he has seen. The scale and fastness were “unprecedented,” he said.

Experts enunciated it was tardily to envisage another onrush on the Facebook platform that would exist more troubling: sending false messages to family and supporters to lure them to malicious sites, where they might be tricked into revealing private information. They warned that hackers could employment the template of this onset to launch copycat efforts.

The presence of the photos upset many Facebook users, who conveyed to Twitter to enunciate they were weighing whether to deactivate their accounts.

Part of Facebook’s success has stemmed from its ability to get developers to make games and other applications that shape seamlessly on the site’s platform. Only handsome such leeway to outside programmers agency the site is likewise vulnerable to hackers, Wisniewski said.

Facebook could exist doing more to stop these kinds of attacks, he said, such equally checking the credentials of programmers who register with the site and bighearted users the choice to double-check any actions before they accept effect. The society has created an endeavor to make things seamless, he said, but convenience often comes at the expense of security.