This is a serious bug, it effects all Kernel versions released since May 2001! That goes all the way back to the early 2.4 versions.
It’s also exploitable according to the report – This issue is easily exploitable for local privilege escalation. In order to exploit this, an attacker would create a mapping at address zero containing code to be executed with privileges of the kernel (which I would assume to be root).
At least it only allows local priveledge escalation, if was a remote root exploit in the kernel..it would be a disaster.
Imagine all the Linux boxes out there connected to the net where the admin doesn’t update or read security resources.
Linux developers have issued a critical update for the open-source OS after researchers uncovered a vulnerability in its kernel that puts most versions built in the past eight years at risk of complete takeover.
The bug involves the way kernel-level routines such as sock_sendpage react when they are left unimplemented. Instead of linking to a corresponding placeholder, (for example, sock_no_accept), the function pointer is left uninitialized. Sock_sendpage doesn’t always validate the pointer before dereferencing it, leaving the OS open to local privilege escalation that can completely compromise the underlying machine.
“Since it leads to the kernel executing code at NULL, the vulnerability is as trivial as it can get to exploit,” security researcher Julien Tinnes writes here. “An attacker can just put code in the first page that will get executed with kernel privileges.”
A patch has been released, so if you have untrusted local users on your system UPDATE YOUR KERNEL NOW!
This is the second time this year there has been a serious exploit in the Linux Kernel, which in a way is good because it means people are looking at it critically.
The more bugs that get exposed, the more secure the Kernel and our operating systems become.
Tinnes and fellow researcher Tavis Ormandy released proof-of-concept code that they said took just a few minutes to adapt from a previous exploit they had. They said all 2.4 and 2.6 version since May 2001 are affected.
Security researchers not involved in the discovery were still studying the advisory at time of writing, but at least one of them said it appeared at first blush to warrant an immediate action.
“This passes my it’s-not-crying-wolf test so far,” said Rodney Thayer, CTO of security research firm Secorix. “If I had some kind of enterprise-class Linux system like a Red Hat Enterprise Linux…I would really go check and see if this looked like it related, and if my vendor was on top of it and did I need to get a kernel patch.”
I wonder if any more major bugs will be disclosed before the end of the year? The less Kernel updates that need to be carried out the better in my books.
Full technical details of the bug can be found here:
Source: The Register