Researchers have observed sophisticated hacking groups conducting automated scans of the internet in search of web servers vulnerable to the theft of data, including passwords, confidential communications and credit card numbers, due to the Heartbleed bug.

Servers may be vulnerable to the bug if they run popular versions of a web encryption program known as OpenSSL used on about two-thirds of all web servers. The issue has gone undetected for about two years.

'Due to the complexity and difficulty in upgrading many of the affected systems, this vulnerability will be on the radar for attackers for years to come.'- Mark Maxey, Accuvant

Kurt Baumgartner, a researcher with security software maker Kaspersky Lab, said his firm uncovered evidence on Monday that a few hacking groups believed to be involved in state-sponsored cyber espionage were running such scans shortly after news of the bug first surfaced the same day.

That number had increased on Wednesday after security software company Rapid7 released a free tool for conducting such scans.

"The problem is insidious," Baumgartner said. "Now it is amateur hour. Everybody is doing it."

servers_220-000015345771

Servers may be vulnerable to the Heartbleed bug if they run popular versions of web encryption software known as OpenSSL, used on about two-thirds of all web servers. (iStock)

It isn't known whether any data has actually been stolen by hackers or cybercriminals making use of the bug in the past couple of years, as such thefts would normally be undetectable.

However, at least one technology specialist has reported signs that the Heartbleed bug may have already been exploited. Terrence Koeman, chief technology officer for the digital production agency MediaMonks, told the technology news site Ars Technica that he had detected scans for the vulnerability dating back to November 2013. And he said the scans came from a network suspected of harbouring "bot" servers — zombie computers controlled over the internet by cybercriminals using malware.

OpenSSL software is used on servers that host websites but not PCs or mobile devices, so even though the bug exposes passwords and other data entered on those devices to hackers, it must be fixed by website operators.

"There is nothing users can do to fix their computers," said Mikko Hypponen, chief research officer with security software maker F-Secure.

A scan of the internet Tuesday night suggested that about a third of servers with the vulnerability had been patched at that time, reported Robert David Graham of Atlanta-based Errata Security on his blog. Still, the scan detected roughly 600,000 servers that were still vulnerable.

Representatives for Facebook Inc., Google and Yahoo Inc. told Reuters they have taken steps to mitigate the impact on users.

Google spokeswoman Dorothy Chou told Reuters: "We fixed this bug early and Google users do not need to change their passwords."

Ty Rogers, a spokesman for Amazon.com Inc, said "Amazon.com is not affected."

Amazon cloud services users affected

In a blog post dated Tuesday, the company said some of its web cloud services, which provide the underlying infrastructure for apps such as online movie-streaming service Netflix and social network Pinterest, had been vulnerable. While it said the problems had been fixed, the company urged users of those services, which are popular in particular among the tech startup community, to take extra steps such as updating software.

Kaspersky Lab's Baumgartner noted that devices besides servers could be at risk because they run software programs with vulnerable OpenSSL code built into them.

They include versions of Cisco Systems Inc's AnyConnect for iOS and Desktop Collaboration, Tor, OpenVPN and Viscosity from Spark Labs. The developers of those programs have either updated their software or published directions for users on how to mitigate potential attacks.

Steve Marquess, president of the OpenSSL Software Foundation, said he could not identify other computer programs that used OpenSSL code that might make devices vulnerable to attack.

New encryption keys

Bruce Schneier, a well-known cryptologist and chief technology officer of Co3 Systems, called on internet companies to issue new certificates and keys for encrypting internet traffic, which would render stolen keys useless.

That will be time-consuming, said Barrett Lyon, chief technology officer of cybersecurity firm Defense.Net Inc. "There's going to be lots of chaotic mess," he said.

Symantec Corp and GoDaddy, two major providers of SSL technology, said they do not charge for reissuing keys.

Mark Maxey, a director with cybersecurity firm Accuvant, said it is no easy task for large organizations to implement the multiple steps to clean up the bug, which means it will take some a long time to do so.

"Due to the complexity and difficulty in upgrading many of the affected systems, this vulnerability will be on the radar for attackers for years to come," he said.

Hypponen of F-Secure said computer users could immediately change passwords on accounts, but they would have to do so again if their operators notify them that they are vulnerable.

"Take care of the passwords that are very important to you," he said. "Maybe change them now, maybe change them in a week. And if you are worried about your credit cards, check your credit card bills very closely."

With a file from Ars Technica