A security vulnerability in the GNU Bourne Again Shell (Bash), the
command-line shell used in many Linux and Unix operating systems, could
leave systems running those operating systems open to exploitation by
specially crafted attacks. “This issue is especially dangerous as there
are many possible ways Bash can be called by an application,” a Red Hat
security advisory warned.
It lands countless websites, servers, PCs, OS X Macs, various home routers, and more, in danger of hijacking by hackers.
The vulnerability is present in Bash up to and including version 4.3, and was discovered by Stephane Chazelas.
It puts Apache web servers, in particular, at risk of compromise: CGI scripts that use or invoke Bash in any way – including any child processes spawned by the scripts – are vulnerable to remote-code injection. OpenSSH and some DHCP clients are also affected on machines that use Bash.
The vulnerability affects versions 1.14 through 4.3 of GNU Bash. Patches have been issued by many of the major Linux distribution vendors for affected versions, including:
To test if your version of Bash is vulnerable to this issue, run the following command:
you are using a vulnerable version of Bash. The patch used to fix this issue ensures that no code is allowed after the end of a Bash function. Thus, if you run the above example with the patched version of Bash, you should get an output similar to:
For More Details Click below link :
https://access.redhat.com/node/1200223
It lands countless websites, servers, PCs, OS X Macs, various home routers, and more, in danger of hijacking by hackers.
The vulnerability is present in Bash up to and including version 4.3, and was discovered by Stephane Chazelas.
It puts Apache web servers, in particular, at risk of compromise: CGI scripts that use or invoke Bash in any way – including any child processes spawned by the scripts – are vulnerable to remote-code injection. OpenSSH and some DHCP clients are also affected on machines that use Bash.
The vulnerability affects versions 1.14 through 4.3 of GNU Bash. Patches have been issued by many of the major Linux distribution vendors for affected versions, including:
- Red Hat Enterprise Linux (versions 4 through 7) and the Fedora distribution
- CentOS (versions 5 through 7)
- Ubuntu 10.04 LTS, 12.04 LTS, and 14.04 LTS
- Debian
To test if your version of Bash is vulnerable to this issue, run the following command:
$ env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
If the output of the above command looks as follows:
vulnerable
this is a test
you are using a vulnerable version of Bash. The patch used to fix this issue ensures that no code is allowed after the end of a Bash function. Thus, if you run the above example with the patched version of Bash, you should get an output similar to:
$ env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
bash: warning: x: ignoring function definition attempt
bash: error importing function definition for `x'
this is a test
For More Details Click below link :
https://access.redhat.com/node/1200223
