Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Vulnerabilities / Threats

4/14/2009
04:21 PM
Connect Directly
Google+
Twitter
RSS
E-Mail
50%
50%

Attack Sneaks Rootkits Into Linux Kernel

A researcher at Black Hat Europe this week will demonstrate a more stealthy way to hack Linux

Kernel rootkits are tough enough to detect, but a researcher this week has demonstrated an even sneakier method of hacking Linux.

The attack attack exploits an oft-forgotten function in Linux versions 2.4 and above in order to quietly insert a rootkit into the operating system kernel as a way to hide malware processes, hijack system calls, and open remote backdoors into the machine, for instance. At Black Hat Europe this week in Amsterdam, Anthony Lineberry, senior software engineer for Flexilis, will demonstrate how to hack the Linux kernel by exploiting the driver interface to physically addressable memory in Linux, called /dev/mem.

"One of bonuses of this [approach] is that most kernel module rootkits make a lot noise when they are inserting [the code]. This one is directly manipulating" the memory, so it's less noticeable, he says.

The /dev/mem "device" can be opened like a file, and you can read and write to it like a text file, Lineberry says. It's normally used for debugging the kernel, for instance.

Lineberry has developed a proof-of-concept attack that reads and writes to kernel memory as well as stores code inside the kernel, and he plans to release a framework at Black Hat that lets you use /dev/mem to "implement rootkit-like behaviors," he says.

The idea of abusing /dev/mem to hack the Linux kernel is not really new, he says. "People have known what you can do with these /dev/mem devices, but I have never seen any rootkits with dev/mem before," he says.

[UPDATE: But Linux experts point out that the technique Lineberry is demonstrating at Black Hat indeed been has been deployed before with the so-called SuckIT rootkit, and as far back as the late 1990s with direct kernel-object modification (DKOM) rootkits].

This method of attack is not as simple as writing a kernel module like a lot of rootkit attacks entail, however, Lineberry says. "This is a lot more tedious and requires a lot more in-depth knowledge of kernel internals and systems architecture ... But the framework enables you to leverage this a little more easily."

And the /dev/mem exploitation is just the first step in an attack on Linux. "After you've exploited a box and have root access, at that point you can use it to maintain that access and anything any rootkit can do -- hiding processes, files, and controlling network traffic," Lineberry says.

Linux system administrators typically aren't aware of the potential dangers of leaving /dev/mem exposed, he says. Lineberry says his goal is to educate them on this potential security hole. And there's now a way to defend against such an attack, too: the Linux development community recently issued a patch to locks down /dev/mem, limiting read and write access from the outside, he says.

"The problem with kernel-based rootkits is that the rootkit can mitigate [detection] because it has control," he says. "It's a race in the kernel to see who's going to see who first."

Have a comment on this story? Please click "Discuss" below. If you'd like to contact Dark Reading's editors directly, send us a message. Kelly Jackson Higgins is Executive Editor at DarkReading.com. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
97% of Americans Can't Ace a Basic Security Test
Steve Zurier, Contributing Writer,  5/20/2019
How Security Vendors Can Address the Cybersecurity Talent Shortage
Rob Rashotte, VP of Global Training and Technical Field Enablement at Fortinet,  5/24/2019
TeamViewer Admits Breach from 2016
Dark Reading Staff 5/20/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Building and Managing an IT Security Operations Program
As cyber threats grow, many organizations are building security operations centers (SOCs) to improve their defenses. In this Tech Digest you will learn tips on how to get the most out of a SOC in your organization - and what to do if you can't afford to build one.
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-7068
PUBLISHED: 2019-05-24
Adobe Acrobat and Reader versions 2019.010.20069 and earlier, 2019.010.20069 and earlier, 2017.011.30113 and earlier version, and 2015.006.30464 and earlier have an use after free vulnerability. Successful exploitation could lead to arbitrary code execution .
CVE-2019-7069
PUBLISHED: 2019-05-24
Adobe Acrobat and Reader versions 2019.010.20069 and earlier, 2019.010.20069 and earlier, 2017.011.30113 and earlier version, and 2015.006.30464 and earlier have a type confusion vulnerability. Successful exploitation could lead to arbitrary code execution .
CVE-2019-7070
PUBLISHED: 2019-05-24
Adobe Acrobat and Reader versions 2019.010.20069 and earlier, 2019.010.20069 and earlier, 2017.011.30113 and earlier version, and 2015.006.30464 and earlier have an use after free vulnerability. Successful exploitation could lead to arbitrary code execution .
CVE-2019-7071
PUBLISHED: 2019-05-24
Adobe Acrobat and Reader versions 2019.010.20069 and earlier, 2019.010.20069 and earlier, 2017.011.30113 and earlier version, and 2015.006.30464 and earlier have an out-of-bounds read vulnerability. Successful exploitation could lead to information disclosure.
CVE-2019-7072
PUBLISHED: 2019-05-24
Adobe Acrobat and Reader versions 2019.010.20069 and earlier, 2019.010.20069 and earlier, 2017.011.30113 and earlier version, and 2015.006.30464 and earlier have an use after free vulnerability. Successful exploitation could lead to arbitrary code execution .