Computer security experts are warning that a serious vulnerability called Shellshock could affect up to 500 million computers and servers worldwide.
Some analysts warn that the problem could be worse than the one caused by the Heartbleed vulnerability in the OpenSSL encryption software, which caused a stir this year.
The US National Vulnerability Database has rated the threat posed by Shellshock as 10/10 in terms of its severity.
The vulnerability, or "bug" as it's called in programmers' language, was discovered in a piece of software known as Bash. What is Bash and why is it important for the security of computer systems?
What is Bash?
Bash is an acronym for “Bourne Again Shell,” which is the name of a command-line environment. It allows users to issue commands to launch various programs built into the computer’s software by typing text. This method is typically used by programmers and would normally not be available to the general public, but Shellshock changes that.
Mac OS X users can run Bash by opening their Terminal, just as Linux users can do, again with Terminal. Linux and Mac OS X are derivatives of the Unix operating system and thus share some features.
What is the vulnerability and how could someone exploit it?
The vulnerability is related to the processing of a Bash feature, known as "environment variables", which allows the user to influence the behavior of the software.
The Bash bug discovered by Linux expert Stéphane Chazelas is of concern because Bash is used by many popular tools to manipulate environment variables.
In theory, an attacker could take over a machine running Bash by inserting the desired environment variables. They could then use the new variables to execute commands, i.e. run programs, on other users' computers. Once that happens, the hacker has taken control.
The concern is heightened by the fact that Bash is also used by the widely used server software, Apache. And therefore, Shellshock could be a backdoor for hackers seeking to take over a server or the websites it may contain, or even use the machine to launch further attacks.
However, all of this is hypothetical, as there are no reports of attacks using the Bash exploit, although most experts believe that such attacks – and even more damaging ones – will occur in the future.
One of the biggest concerns is that attackers will use Shellshock to create worms – attacks that automatically spread from machine to machine.
Is my computer at risk?
Potential risks may exist for Mac OS X in certain cases where some scripts receive data from untrusted sources on the internet.
For advanced users, there are details at apple.stackexchange.com. For the less experienced, it is recommended to wait for the official update from Apple.
Linux users should consult the websites of the maintainers of the version they use (RedHat, Ubuntu, Debian, CentOS or any other).
What should I do now?
It's obvious, but many don't, despite warnings: patch your system now. Anyone who manages websites that "run" on the above operating systems should proceed as quickly as possible.
It should be noted that doubts are expressed about the degree of effectiveness of the available patches. However, in any case, they will limit the scope of any attacks.
Source: left.gr
