Three Flaws in the Linux Kernel Since 2006 Could Grant Root Privileges

"Three recently unearthed vulnerabilities in the Linux kernel, located in the iSCSI module used for accessing shared data storage facilities, could allow root privileges to anyone with a user account," reports SC Media:

"If you already had execution on a box, either because you have a user account on the machine, or you've compromised some service that doesn't have repaired permissions, you can do whatever you want basically," said Adam Nichols, principal of the Software Security practice at GRIMM. While the vulnerabilities "are in code that is not remotely accessible, so this isn't like a remote exploit," said Nichols, they are still troublesome. They take "any existing threat that might be there. It just makes it that much worse," he explained. "And if you have users on the system that you don't really trust with root access it, it breaks them as well."


Referring to the theory that 'many eyes make all bugs shallow,' Linux code "is not getting many eyes or the eyes are looking at it and saying that seems fine," said Nichols. "But, [the bugs] have been in there since the code was first written, and they haven't really changed over the last 15 years...." That the flaws slipped detection for so long has a lot to do with the sprawl of the the Linux kernel. It "has gotten so big" and "there's so much code there," said Nichols. "The real strategy is make sure you're loading as little code as possible."


The bugs are in all Linux distributions, Nichols said, although the kernel driver is not loaded by default. Whether a normal user can load the vulnerable kernel module varies. They can, for instance, on all Red Hat based distros that GRIMM tested, he said. "Even though it's not loaded by default, you can get it loaded and then of course you can exploit it without any trouble...."


The bugs have been patched in the following kernel releases: 5.11.4, 5.10.21, 5.4.103, 4.19.179, 4.14.224, 4.9.260, and 4.4.260. All older kernels are end-of- life and will not receive patches.

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