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posted by n1 on Thursday September 25 2014, @01:59AM   Printer-friendly
from the well,-that's-not-ideal dept.

Ars reports that a new bug has been found in GNU Bash allows remote attackers to execute arbitrary code by setting the process trailing strings after function definitions in the values of environment variables.

This bug is reported to be present in RHEL (ver 4 through 7), Fedora, CentOS (ver 5 through 7), Ubuntu (ver 10.04 LTS, 12.04 LTS, and 14.04 LTS), Debian, and even OS X Mavericks.

This bug is exploitable through Apache servers with mod_cgi and mod_cgid loaded, OpenSSH, malicious DHCP servers in a compromised wireless access point through dhclient, as well as the CUPS printing system.

The Ars also includes a simple single liner that will test your setup for the newly found discovery:

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

A vulnerable system will output the following:

vulnerable
 this is a test

While a patched or unaffected system outputs:

bash: warning: x: ignoring function definition attempt
bash: error importing function definition for `x'
this is a test

A patch is already out, so administrators are advised to update Bash.

Editor's Update: Security Engineer Tavis Ormandy has said "The bash patch seems incomplete to me, function parsing is still brittle".

$ env X='() { (a)=>\' sh -c "echo date"; cat echo

 
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  • (Score: 0) by Anonymous Coward on Thursday September 25 2014, @01:29PM

    by Anonymous Coward on Thursday September 25 2014, @01:29PM (#98208)

    I *think* he means use more modern ideas and practices. C++ does not get you that. Avoiding shortcuty language idioms does though. If its not clear it is hard to maintain. Take for example the libressl thing. They are going thru and refactoring. But a lot of what they are doing is yanking out 15 year old C compiler and CRT workarounds. Lots of bad decisions are falling out because of that. Not because of the language they are using. It is the same one.

    Picking one language over another does not get you good practices. In fact some languages teach you bad practices in other languages (ie learning garbage collection and then thinking its ok to do in C++). Each language has its own set of 'best practices'. Either you use them or bitch about them. Bitching gets you nothing other than wasted time.

    This is a case of someone did not sanitize the inputs. This is a problem in almost all languages. It is a design problem. Some languages make it harder to do but they all can do it. Especially when you are at the translation layer in your systems. Most SQL injection attacks do not attack the interpreter but the sql server on the other side by abusing the interpreter because it did not sanitize.