Heartbleed
The logo adopted for the Heartbleed bug. Photo by Screenshot
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A newly discovered bug in widely-used Web encryption technology has made data on many of the world's major websites vulnerable to theft by hackers, in what experts say is one of the most serious security flaws uncovered in recent years.

The discovery prompted the U.S. government's Department of Homeland Security to advise businesses on Tuesday to review their servers to see if they were using vulnerable versions a type of software known as OpenSSL.
Nicknamed "Heartbleed," the vulnerability was discovered by researchers from Google and a small security firm named Codenomicon,

Homeland Security said updates are already available to address the vulnerability in OpenSSL, which could enable remote attackers to access sensitive data, including passwords and secret keys that can decode traffic as it travels across the Internet.

"We have tested some of our own services from an attacker's perspective. We attacked ourselves from outside, without leaving a trace," Codenomicon said on a website it built to provide information about the threat, heartbleed.com.

With the bug having been in existence for about two years, computer security experts warned that victims will not be able to tell if their data has been accessed.

"If a website is vulnerable, I could see things like your password, banking information and healthcare data, which you were under the impression you were sending securely to your website," said Michael Coates, director of product security for Shape Security.

The fix for the bug needs to be implemented by both the server and the user. "Service providers and users have to install the fix as it becomes available for the operating systems, networked appliances and software they use," according to heartbleed.com

Chris Eng, vice president of research with software security firm Veracode, said he estimates that hundreds of thousands of web and email servers around the globe need to be patched as soon as possible to protect them from attack by hackers who will rush to exploit the vulnerability, now that it is publicly known.

The technology website Ars Technica reported that security researcher Mark Loman was able to extract data from Yahoo Mail servers by using a free tool.

A spokesperson for Yahoo confirmed that Yahoo Mail was vulnerable to attack, but said it had been patched along with other main Yahoo sites, such as Yahoo Search, Finance, Sports, Flickr and Tumblr.

"We are working to implement the fix across the rest of our sites right now," she said on Tuesday evening.