Stack Clash vulnerability

A new vulnerability was announced today affecting all Linux servers (including OpenBSD, NetBSD, FreeBSD and Solaris, on i386 and amd64).  The vulnerability allows local users to corrupt memory and execute arbitrary code.

We are currently contacting customers to arrange for appropriate times to reboot servers and load in the new kernel. 

If you manage your own server we highly recommend you fully patch and reboot your server ASAP.

If you are using a VPS server you will likely need to wait for confirmation from your VPS vendor that they have made a new kernel available.  Do make sure that when you reboot you boot into the new kernel and not the old one.  We are doing this for customers and have already had replies from some providers.

Anyone using an operating system that is now end of life (such as Ubuntu 12.04) will have to upgrade their operating system.  Some vendors do have additional support offerings.  Canonical is offering Extended Security Support for Ubuntu Advantage customers which will cover this vulnerability.

More technical information can be found in the excellent write up from Qualys who discovered the vulnerability.

“Each program running on a computer uses a special memory region called the stack. This memory region is special because it grows automatically when the program needs more stack memory. But if it grows too much and gets too close to another memory region, the program may confuse the stack with the other memory region. An attacker can exploit this confusion to overwrite the stack with the other memory region, or the other way around.”

If you do not have a support contact in place with us and would like help with this please feel free to contact us.

Feature image by Steven Lilley under the CC BY-SA 2.0 license.