A “deadly serious” bug potentially affecting hundreds of millions of computers, servers and devices has been discovered.
The flaw has been found in a software component known as Bash, which is a part of many Linux systems as well as Apple’s Mac operating system.
The bug, dubbed Shellshock, can be used to remotely take control of almost any system using Bash, researchers said.
“Whereas something like Heartbleed was all about sniffing what was going on, this was about giving you direct access to the system,” Prof Alan Woodward, a security researcher from the University of Surrey, told the BBC.
“The door’s wide open.”
Some 500,000 machines worldwide were thought to have been vulnerable to Heartbleed. But early estimates, which experts said were conservative, suggest that Shellshock could hit at least 500 million machines.
The problem is particularly serious given that many web servers are run using the Apache system, software which includes the Bash component.
Bash – which stands for Bourne-Again SHell – is a command prompt on many Unix computers. Unix is an operating system on which many others are built, such as Linux and Mac OS.
However, other security researchers warned that the patches were “incomplete” and would not fully secure systems.
Of particular concern to security experts is the simplicity of carrying out attacks that make use of the bug.
Cybersecurity specialists Rapid7 rated the Bash bug as 10 out of 10 for severity, but “low” on complexity – a relatively easy vulnerability for hackers to capitalise on.
“Using this vulnerability, attackers can potentially take over the operating system, access confidential information, make changes, et cetera,” said Tod Beardsley, a Rapid7 engineer.
“Anybody with systems using Bash needs to deploy the patch immediately.”
For general home users, Prof Woodward suggested simply keeping an eye on manufacturer websites for updates – particularly for hardware such as broadband routers.