Earlier this week security updates were made available by Siemens for its Simatic products (Industrial Data Network Controllers) to resolve an issue in the GNU C library that was reported in January this year. Updates were already available for its Ruggedcom (industrial routers) and its SINUMERIK controllers in March. These products are deployed in industrial sectors to provide data networking capabilities within large production lines and processing facilities e.g. water treatment.
Please follow the instructions within the ICS CERT security advisory to update any affected industrial Siemens products that you may be using.
Background on the Ghost Flaw
In January of this year a buffer overflow affecting the gethostbyname() and gethostbyname2() functions within the GNU C library was discovered by security researchers at Qualys. Both functions are considered deprecated since a newer function getaddrinfo() replaces them. This is a denial of service flaw (in the context of the above mentioned industrial networking components) but there is a possibility of remote code execution.
This flaw was caused by an efficiency improvement within the gethostbyname(). If this function receives an IP address, it will not have to resolve a hostname to an IP address for you (by using a DNS lookup) since the parameter passed is already an IP address. However this code does not check the length of the IP address passed to it as a parameter and this causes the buffer overflow. Please note that the parameter being passed to this function would need to be specifically chosen to crash the code in a way that allows remote code execution for that specific software and hardware platform. Thus such attacks would need to more targeted and would not be trivial to exploit.
Updates to resolve this flaw were released in January by Red Hat, SUSE Linux, Ubuntu and Debian (among others). If you have not already done so, please apply any security updates to your Linux systems and restart those systems for the updates to take effect.
Update: 29th May 2015:
Further defence in-depth advice concerning how to defend a Linux system from attack is provided in this blog post.
Update: 7th September 2015: In addition, as mentioned in this more recent blog post, the Linux Foundation has published a security checklist (intended for Linux system administrators) to harden Linux systems against attack.