Linux kernel flaw endangers millions of PCs, servers and Android devices
IT News
The vulnerability could allow malicious apps or hackers to gain root
access from a limited account
By Lucian Constantin Follow
IDG News Service | Jan 19, 2016 6:13 AM PT
For almost three years, a serious vulnerability in the Linux kernel
could have allowed attackers to take full control over Linux-based PCs,
servers, Android phones and other embedded devices.
The flaw, which stems from the kernel's keyring facility, allows
applications running under a local user to execute code in the kernel.
As a result, an attacker with access to only a limited account on a
Linux system can escalate their privileges to root.
The vulnerability, tracked as CVE-2016-0728, was found and reported to
the Linux kernel security team and several Linux distribution
maintainers by researchers from an Israeli threat defense start-up
called Perception Point.
The Linux kernel is the core of all Linux-based operating systems,
including Android. Its keyring facility provides a way for applications
to store sensitive information such as authentication and encryption
keys inside the kernel, where other user-space applications cannot
access it.
The Perception Point researchers found a way to trick the kernel into
freeing a still-referenced keyring object and then to overwrite it with
malicious content so it gets executed. According to them, the
vulnerability was introduced in kernel version 3.8, released in Feb. 2013.
Linux distributions will release security patches for this vulnerability
this week, so users should update their kernels as soon as possible.
However, some systems will likely remain vulnerable for some time to
come, if not indefinitely.
For example, automatic updates are not enabled on many Linux-based
production servers, said Yevgeny Pats, co-founder and CEO of Perception
Point. In such environments administrators sometimes have to test the
updates before deploying them, which can introduce significant patching
delays.
What makes this vulnerability stand out compared to other Linux kernel
privilege escalation flaws is that it affects all architectures,
including ARM.
This means that many embedded devices that run one of the affected
kernel versions released over the past three years are also vulnerable.
This includes devices running Android 4.4 (KitKat) and later, which
currently account for almost 70 percent of all Android devices.
The Android ecosystem is known for its version fragmentation and long
update delays. Google shares security patches with Android device
manufacturers, who then have to apply them to their separately
maintained source code trees and build updated firmware packages for
each of their products. Some of the updates then need to be distributed
to users with the help of mobile carriers.
Most Android devices receive software support for only 18 months after
which they're cut off from patches. This means that a considerable
number of devices will never receive a fix for this vulnerability.
The situation is not very different with consumer routers and other
embedded devices that need to be manually updated by users and for which
firmware patches are rare to begin with.
CPU-based protections like Supervisor Mode Access Prevention (SMAP) and
Supervisor Mode Execution Protection (SMEP), or features like SELinux on
Android can make exploiting this vulnerability harder, but there are
ways to bypass such mitigations, Pats said.
Perception Point is not aware of any attack exploiting this
vulnerability in the wild, but the company believes that computers
emergency response teams and larger security vendors might be in a
better position to discover if such attacks have happened.
--
*================================================ Duane Whittingham -
N9SSN (ARES/RACES, EmComm, Skywarn & Red Cross)
http://www.radiodude.info ================================================*
_______________________________________________
Medianews mailing list
Medianews@etskywarn.net
http://etskywarn.net/mailman/listinfo/medianews_etskywarn.net