After Adobe Systems asked them to keep quiet about their findings, two security researchers have pulled out of a technical talk where they were going to demonstrate how they could seize control of a victim's browser using an online attack called clickjacking.Robert Hansen and Jeremiah Grossman had been set to deliver their talk next week at the OWASP (Open Web Application Security Project) conference in New York. But the proof of concept code they'd developed to show how their clickjacking attack worked divulged a bug in one of Adobe's products. After a week of discussions with Adobe, the researchers decided last Friday to pull the talk.Although Hansen and Grossman believe that the clickjacking flaw ultimately lies in the way that Internet browsers are designed, Adobe convinced them to hold off on their discussion until they could release a patch. "Adobe thinks they can do something to make the hack harder," said Grossman, CTO with White Hat Security, in an interview.In a clickjacking attack, the attacker tricks the victim into clicking on malicious Web links without realizing it. This type of attack has been known for years, but had not been considered to be particularly dangerous. Security experts had thought it could be used to commit advertising click fraud or to inflate Digg ratings for a Web page, for example.However, in writing their proof-of-concept code, Hansen and Grossman realized that clickjacking was actually more serious than they'd first thought."When we finally built it and got the proof of concept it was quite nasty," said Grossman. "If I control what you click on, how much bad can I do? It turns out you can do a number of really, really bad things."Neither Grossman nor Hansen, CEO of consultancy SecTheory, wanted to get into specifics of their attack. However, Tom Brennan, the OWASP conference organizer said that he has seen the attack code demonstrated and that it allows the attacker to take complete control of the victim's desktop.The researchers say that they were not pressured by Adobe to drop their talk. "This is not an evil 'the man is trying to keep us hackers down' situation," Hansen wrote Monday on his blog.Late Monday, Adobe posted a note, thanking the researchers for keeping the bug private and indicating that the company is working on patching the problem.Even if disclosing the bug may help attackers, OWASP's Brennan said that the researchers should still go ahead and give their talk in order to give IT professionals an opportunity to understand the real nature of the threat. "There is a zero-day problem in browsers that is affecting millions of people today," he said. "When a person discusses it, it puts everyone on the same playing field."Hansen and Grossman say that they also expect Microsoft to patch a related bug in Internet Explorer, and that many other browsers are also affected by the clickjacking problem. "We believe it is more or less a browser security problem," Grossman said.