I'm writing this blog post to provide some information and assistance to anyone affected by the recent Linux kernel vulnerability CVE-2010-3081, which unfortunately is just about everyone running 64-bit Linux. To make matters worse, in the last day we've received many reports of people attacking production systems using an exploit for this vulnerability, so if you run Linux systems, we recommend that you strongly consider patching this vulnerability. (Linux vendors release important security updates every month, but this vulnerability is particularly high profile and people are using it aggressively to exploit systems).
This vulnerability was introduced into the Linux kernel in April 2008, and so essentially every distribution is affected, including RHEL, CentOS, Debian, Ubuntu, Parallels Virtuozzo Containers, OpenVZ, CloudLinux, and SuSE, among others. A few vendors have released kernels that fix the vulnerability if you reboot, but other vendors, including Red Hat, are still working on releasing an updated kernel.
The published workarounds that we've seen, including the workaround recommended by Red Hat, can themselves be worked around by an attacker to still exploit the system. For now, to be responsible and avoid helping attackers, we don't want to provide those technical details publicly; we've contacted Red Hat and other vendors with the details and we'll cover them in a future blog post, in a few weeks.
Although it might seem self-serving, I do know of one sure way to fix this vulnerability right away on running production systems, and it doesn't even require you to reboot: you can (for free) download Ksplice Uptrack and fully update any of the distributions that we support (We support RHEL, CentOS, Debian, Ubuntu, Parallels Virtuozzo Containers, OpenVZ, and CloudLinux. For high profile updates like this one, Ksplice optionally makes available an update for your distribution before your distribution officially releases a new kernel). We provide a free 30-day trial of Ksplice Uptrack on our website, and you can use this free trial to protect your systems, even if you cannot arrange to reboot anytime soon. It's the best that we can do to help in this situation, and I hope that it's useful to you.
Note: If an attacker has already compromised one of your machines using an exploit for CVE-2010-3081, simply updating the system will not eliminate the presence of an attacker. Similarly, if a machine has already been exploited, then the exploit may continue working on that system even after it has been updated, because of a backdoor that the exploit installs. We've published a test tool to check whether your system has already been compromised by the public CVE-2010-3081 exploit code that we've seen. If one or more of your machines has already been compromised by an attacker, we recommend that you use your normal procedure for dealing with that situation.