Heartbleed hackers steal encryption keys to illustrate risks

CloudFlare Inc. sponsored a contest to see how easily hackers could exploit the Heartbleed bug. CloudFlare Inc. sponsored a contest to see how easily hackers could exploit the Heartbleed bug. Photo: Pawel Kopczynski, Reuters Photo: Pawel Kopczynski, Reuters Image 1 of / 1 Caption Close Heartbleed hackers steal encryption keys to illustrate risks 1 / 1 Back to Gallery

The crown jewel of secure websites is a single string of data - a very long jumble of letters and numbers and symbols that looks like gibberish. The Heartbleed bug allows hackers to crack it.

Security professionals demonstrated last weekend that the recently disclosed Heartbleed bug can be exploited to allow criminals and intelligence agencies to make off with one of the most sought-after prizes in hacking: the private keys that websites rely on to decrypt sensitive information, including passwords, banking details and health data.

At least six people were able to extract the private key of a website in a test of the bug's viability organized by CloudFlare Inc., said Nick Sullivan, a security architect with the Internet security company. The results suggest hackers have stolen encryption keys using the bug and are planning attacks, he said.

The company set up the competition after stating in an April 11 blog post that stealing keys appeared to be very hard or impossible using Heartbleed, one of the biggest holes in the history of the Internet. "It turns out we were wrong," CloudFlare now says. Sullivan said in an e-mail Sunday that the company is planning to replace the keys it manages for clients anyway to be safe and that the contest "made us more confident that the cost was worthwhile."

Heartbleed's danger

The evidence that a widely used form of encryption called OpenSSL can be undermined, giving attackers potential access to websites' future and past communications, validated fears about Heartbleed's danger and added urgency to efforts now entering their second week to fix computer systems containing it.

Since its discovery, there has been much discussion about how the flaw could have gone undetected for so long and whether criminal hackers or government intelligence units might have exploited it.

Bloomberg News reported on April 11 that the National Security Agency knew about the bug for two years and made it part of its hacking toolkit. The NSA has since denied that it knew of the Internet hole before an April 7 report by private security researchers.

Millions of smartphones and tablets running Google's Android software are vulnerable to the bug, as are networking products from Cisco Systems and Juniper Networks. Dozens of entities are conducting Internet-wide attack attempts seeking to exploit Heartbleed, including computers in China that have been associated with hacking, said J. Alex Halderman, an assistant professor of electrical engineering and computer science at the University of Michigan tracking the attacks.

Sites have no way of knowing whether their encryption codes have been stolen, and criminals will soon find ways to automate techniques for taking them, said Jeremiah Grossman, a Web application specialist and founder of WhiteHat Security Inc.

"Exploitability matters a great deal!" Grossman wrote in an e-mail. "After that proof is done, then the black hat tool to make it scale will come next. And just because the issue is patched doesn't mean the risk is over - far from it."

Serious Internet hole

Heartbleed, the result of a simple programming error, is the kind of security hole that is discovered every few years, widespread and serious enough that it sends technology companies around the world scrambling to protect their networks.

Writing the code to exploit it takes creativity and patience. Good exploit code is something of an art form, and skilled hackers have signature techniques. Finding a bug and figuring out that it is exploitable are just the first steps.

Intelligence agencies and criminal syndicates take what they know and create hacking packages that can be used off the shelf to compromise networks. Thus, a single bug can spawn multiple types of attack bundles. The goal is to maximize the ability to penetrate a target, while minimizing the chance of discovery.

The Heartbleed bug could therefore have many consequences, but the ability to steal private encryption keys is the most severe.

In encryption, private keys are like the keys to a house. Only you have them, and they are closely guarded. Public keys, on the other hand, are what everyone on the Internet sees when they want to communicate securely with a website. The two are paired.

Stealing the private key gives an intruder unfettered access to their targets, allowing them to capture data flowing between websites' servers and users' computers.

So far, efforts to fix vulnerable systems appear to be working. The majority of websites that had the bug have applied a software patch that protects them. About 12 percent have not, according to a site called www.istheinternetfixedyet.com tracking the progress.

An urgent concern now is that they all revoke the Secure Sockets Layer, or SSL, digital certificates that handle their data encryption and contain keys that might have already been stolen by hackers.

The researchers who discovered Heartbleed said the bug could exist inside hundreds of millions of websites, based on the market share of the open-source software that uses OpenSSL. The number is actually closer to 500,000, because only a fraction of sites had the vulnerable functionality turned on, according to Netcraft Ltd., an online security firm in Bath, United Kingdom, whose data the researchers used for their original estimate.

Multiple computers

CloudFlare's test site got 44 million hacking attempts from 2,921 unique Internet protocol addresses, the company said. The number of contestants was smaller because some people used multiple computers.

The contest was designed as a realistic simulation for an attack, and the contest server used the same software as one-seventh of all websites, Sullivan said.