On July 16, Brad Spengler disclosed an easily-exploitable kernel vulnerability based on getting the kernel to dereference a null pointer. This security hole affected a version of the kernel which had not been widely distributed, so it was a problem for relatively few users, but it highlighted a class of problems which was sure to be seen again.

We think that it's important for developers and system administrators to be more knowledgeable about the attacks that black hats regularly use to take control of systems, and so, today, we're going to start from where we left off and go all the way to a working exploit for a NULL pointer dereference in a toy kernel module.

Brad Spengler, the developer behind the Grsecurity project, has published an exploit for a vulnerability in the Tun interface in Linux kernel 2.6.30 and 2.6.18, used in Red Hat Enterprise Linux 5 (RHEL5), which can be exploited by attackers to obtain root privileges. Of particular interest is the fact that the exploit is even able to circumvent security extensions such as SELinux.

A software developer has uncovered a bug in most versions of Linux that could allow untrusted users to gain complete control over the open-source operating system. The null pointer dereference flaw was only fixed in the upcoming 2.6.32 release candidate of the Linux kernel, making virtually all production versions in use at the moment vulnerable.

A vulnerability has been reported in the Linux kernel's memory management allows applications to execute code at root privilege level. The flaw appears to have been introduced into the kernel with version 2.6

But this exploit suggests that there could be a whole class of related problems in the kernel; there is a definite chance that similar vulnerabilities could be discovered - if, indeed, they have not already been found.

A security researcher has released zero-day code for a flaw in the Linux kernel, saying that it bypasses security protections in the operating system. The source code for the exploit was made available last week by researcher Brad Spengler on the Dailydave mailing list.

Flawed sudo code allows users with limited privileges to obtain root privileges

Several Linux distributors are releasing updated kernel packages to close security holes in the kernel.