Category: kernel

Jan 03 2018

“Meltdown” and “Spectre”: Every modern processor has unfixable security flaws

Windows, Linux, and macOS have all received security patches that significantly alter how the operating systems handle virtual memory in order to protect against a hitherto undisclosed flaw. This is more than a little notable; it's been clear that Microsoft and the Linux kernel developers have been informed of some non-public security issue and have been rushing to fix it. But nobody knew quite what the problem was, leading to lots of speculation and experimentation based on pre-releases of the patches.

Now we know what the flaw is. And it's not great news, because there are in fact two related families of flaws with similar impact, and only one of them has any easy fix.

The flaws have been named Meltdown and Spectre. Meltdown was independently discovered by three groups—researchers from the Technical University of Graz in Austria, German security firm Cerberus Security, and Google's Project Zero. Spectre was discovered independently by Project Zero and independent researcher Paul Kocher.

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Sep 08 2016

Linux Hacker Arrested After Traffic Stop

So it seems the alleged hacker has finally been caught, kinda by accident after being stopped for a traffic violation. It was quite a high profile hack, especially in the open source community as anyone downloading kernel files during that period could have theoretically been compromised. It’s unlikely the kernel code was actually...

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Jan 19 2016

Linux bug imperils tens of millions of PCs, servers, and Android phones

(credit: amalthya)

For almost three years, millions of servers and smaller devices running Linux have been vulnerable to attacks that allow an unprivileged app or user to gain nearly unfettered root access. Major Linux distributors are expected to fix the privilege escalation bug this week, but the difficulty of releasing updates for Android handsets and embedded devices means many people may remain susceptible for months or years.

The flaw, which was introduced into the Linux kernel in version 3.8 released in early 2013, resides in the OS keyring. The facility allows apps to store encryption keys, authentication tokens, and other sensitive security data inside the kernel while remaining in a form that can't be accessed by other apps. According to a blog post published Tuesday, researchers from security firm Perception Point discovered and privately reported the bug to Linux kernel maintainers. To demonstrate the risk the bug posed, the researchers also developed a proof-of-concept exploit that replaces a keyring object stored in memory with code that's executed by the kernel.

The vulnerability is notable because it's exploitable in a wide array of settings. On servers, people with local access can exploit it to achieve complete root access. On smartphones running Android versions KitKat and later, it can allow a malicious app to break out of the normal security sandbox to gain control of underlying OS functions. It can also be exploited on devices and appliances running embedded versions of Linux. While security mitigations such as supervisor mode access prevention and supervisor mode execution protection are available for many servers, and security enhanced Linux built into Android can make exploits harder, there are still ways to bypass those protections.

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Mar 09 2015

Cutting-edge hack gives super user status by exploiting DRAM weakness

In one of more impressive hacks in recent memory, researchers have devised an attack that exploits physical weaknesses in certain types of DDR memory chips to elevate the system rights of untrusted users of Intel-compatible PCs running Linux.

The technique, outlined in a blog post published Monday by Google's Project Zero security initiative, works by reversing individual bits of data stored in DDR3 chip modules known as DIMMs. Last year, scientists proved that such "bit flipping" could be accomplished by repeatedly accessing small regions of memory, a feat that—like a magician who transforms a horse into a rabbit—allowed them to change the value of contents stored in computer memory. The research unveiled Monday showed how to fold such bit flipping into an actual attack.

"The thing that is really impressive to me in what we see here is in some sense an analog- and manufacturing-related bug that is potentially exploitable in software," David Kanter, senior editor of the Microprocessor Report, told Ars. "This is reaching down into the underlying physics of the hardware, which from my standpoint is cool to see. In essence, the exploit is jumping several layers of the stack."

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