LinkedIn fixes critical bug

Business networking site LinkedIn has remedied a dangerous zero-day vulnerability in its Internet Explorer toolbar, one day after researchers went public with the exploit code.

The mandatory fix "was pushed out to all of our users" on Wednesday, Mario Sundar, community evangelist at LinkedIn, told SCMagazine.com today. "The fix is required for users; otherwise the toolbar shuts down."

There were no reports of active exploits, he said.

The client-side ActiveX flaw, which garnered Secunia's highest severity rating of "extremely critical," could have allowed an attacker to remotely execute arbitrary code. Users can be exploited when they visit a malicious website. The bug is caused by an error in the toolbar when handling the "Search () method."

One of the discovering researchers, Jared DeMott of Michigan-based VDA Labs, said he and his partner, Justin Seitz, decided to drop the vulnerability "0-day style" after officials at LinkedIn would not pay VDA for consulting fees or to purchase the flaw outright.

"We ultimately really want to protect the end-users," DeMott said in an email to SCMagazine.com on Wednesday. "And if a company won't spend money on security testing, they're not thinking about their end-users...Vendors should be responsible to consider the security of their users."

A spokeswoman for LinkedIn, which has more than 12 million members, said company policy is to not respond to such requests.

Click here to email reporter Dan Kaplan.