Shellshock – Bash VulnerabilitySeptember 24, 2014
Shellshock is a serious security vulnerability in Bourne-Again SHell (BASH) on Linux.
Known as the “Bash Bug” or “ShellShock”, the GNU Bash Remote Code Execution Vulnerability (CVE-2014-6271) could allow an attacker to gain control over a targeted computer if exploited successfully.
First disclosed on 24 September 2014, the vulnerability potentially affects most versions of Linux and Unix operating systems, in addition to Mac OS X (which is based around Unix).
Within an hour of the announcement of the Bash vulnerability, there were reports of machines being compromised by the bug. By 25 September 2014, botnets based on computers compromised with exploits based on the bug were being used by attackers for distributed denial-of-service (DDoS) attacks and vulnerability scanning.
On 26 September 2014, a Shellshock-related botnet was being used for a DDoS attack against Akamai Technologies and to scan the United States Department of Defense.
By 30 September, the website performance firm CloudFlare said it was tracking approximately 1.5 million attacks and probes per day related to the bug.
The vulnerability affects Bash, a common component known as a shell, that appears in many versions of Linux and Unix. Bash acts as a command language interpreter. In other words, it allows the user to type commands into a simple text-based window, which the operating system will then run.
Bash can also be used to run commands passed to it by applications and it is this feature that the vulnerability affects. One type of command that can be sent to Bash allows environment variables to be set.
According to RedHat, “An attacker could use this flaw to override or bypass environment restrictions to execute shell commands. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue.”
Environment variables are dynamic, named values that affect the way processes are run on a computer. The vulnerability lies in the fact that an attacker can tack-on malicious code to the environment variable, which will run once the variable is received.
Discovered on 12 September 2014, analysis of the source code history of Bash shows the vulnerabilities had existed since version 1.03 of Bash released in September 1989. The developers (and current maintainers) of BASH were immediately notified by the discoverer, in order to allow time to develop and test a security patch.
There was an original fix published for CVE-2014-6271, but within days, a second advisory was issued (CVE-2014-7169) to address further risks. Intense scrutiny of the underlying design flaws discovered a variety of related vulnerabilities, (CVE-2014-6277, CVE-2014-6278, CVE-2014-7169, CVE-2014-7186, and CVE-2014-7187); which maintainer Chet Ramey addressed with a series of further patches.
Some Digital Tsunami client sites are hosted on our own, or client-exclusive, private clouds on Linux-based platforms. These clouds had the potential to be exposed to this vulnerability.
However, within hours of the official announcement of the vulnerability, the security patch was applied to all Digital Tsunami Linux web servers. Sites hosted on the Windows platform are not subject to the vulnerability.
No Digital Tsunami clients on our private clouds were affected by the recent Heartbleed vulnerability.
Sites hosted on external servers will remain at risk until security patches are applied.
For enquiries on advanced security for your web presence, please contact Digital Tsunami Sales or Technical Support.
From Our Clients
Andrew has provided Merrell Associates with reliable service, bringing a vast wealth of knowledge in IT to the task for more than the eight years I have been working here.
We have been helped by Andrew to solve all sorts of problems and if there isn't an immediate fix, solutions are found pretty quickly.
Andrew was able to create an entirely new website in a short period of time and to budget. He and his team worked very well with both our Marketing and IT team.
I have viewed all the videos and would like to commend you on the excellent quality.
I would like to thank you for the excellent editing which portrays the event as dynamic and stimulating.
Thank you for the development of an updated brand image for Wah Yuet in China.
While originally contracted to produce a video highlighting Wah Yuet's manufacturing capabilities, it was apparent very quickly that your understanding of our requirements, combined with your experience, were the perfect fit to create a new logo and style guidelines for the company. While relatively small in scope, you were dedicated to the success of the project and I am pleased to say that you hit the bullseye!
I recently engaged Digital Tsunami to design and build my 60-page website. I'm a website copywriter who relies heavily on web-generated business, so my own online presence needs to be impeccable.
The solution that Digital Tsunami supplied is brilliant. It meets my needs perfectly; it's clean, bold, elegant, fast, and easy to edit. I've had lots of very positive feedback about it, and since launch, my request for quote rate and conversion rate have increased markedly.
The team at Digital Tsunami was incredibly responsive, delivering a solution well ahead of deadline. Their technical knowledge was exceptional, they were innovative, and they were very meticulous. What's more, they understood my business and technical requirements and translated them into a user-friendly, refined, professional site which is conceptually simple and cohesive.
I have no hesitation in recommending the website design services of Digital Tsunami to any business .. that needs a stand-out online presence.