Kernel rootkits and countermeasures
The Spy Within
© © Igor Korionov, 123rf. .com
Rootkits allow attackers to take complete control of a computer. We describe the tricks intruders use to gain access to the Linux kernel and provide guidelines on hardening the kernel against such attacks.
In response to a question asked in parliament, the German Federal Government responded in May 2012 that it was able to decrypt PGP messages or SSH connections, at least partially [1]. Experts were exasperated when they heard this. No one seriously believed that PGP encryption had been cracked. More likely, data is sniffed before encryption or after decryption, or the secret service possesses the private key and, possibly, the associated password. Germany's "Federal Trojan" [2] can infiltrate the kernel as a rootkit for this purpose.
Classically, the term "rootkit" refers to a piece of software that gives an attacker camouflaged access to, and thus control over, a machine. Userland rootkits tend to modify applications to do this. In comparison, the much more powerful kernel rootkits change kernel data structures and code – for example, through system call hijacking.
Hijacked
Hijacking a system call is simple in theory. A system call, which is a job for the operating system kernel, is identified by a number that is used as an index in a table with function addresses. These addresses point to functions that implement the respective system calls. In the Linux kernel, this table is sys_call_table.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Chaos Comes to KDE in KaOS
KaOS devs are making a major change to the distribution, and it all comes down to one system.
-
New Linux Botnet Discovered
The SSHStalker botnet uses IRC C2 to control systems via legacy Linux kernel exploits.
-
The Next Linux Kernel Turns 7.0
Linus Torvalds has announced that after Linux kernel 6.19, we'll finally reach the 7.0 iteration stage.
-
Linux From Scratch Drops SysVinit Support
LFS will no longer support SysVinit.
-
LibreOffice 26.2 Now Available
With new features, improvements, and bug fixes, LibreOffice 26.2 delivers a modern, polished office suite without compromise.
-
Linux Kernel Project Releases Project Continuity Document
What happens to Linux when there's no Linus? It's a question many of us have asked over the years, and it seems it's also on the minds of the Linux kernel project.
-
Mecha Systems Introduces Linux Handheld
Mecha Systems has revealed its Mecha Comet, a new handheld computer powered by – you guessed it – Linux.
-
MX Linux 25.1 Features Dual Init System ISO
The latest release of MX Linux caters to lovers of two different init systems and even offers instructions on how to transition.
-
Photoshop on Linux?
A developer has patched Wine so that it'll run specific versions of Photoshop that depend on Adobe Creative Cloud.
-
Linux Mint 22.3 Now Available with New Tools
Linux Mint 22.3 has been released with a pair of new tools for system admins and some pretty cool new features.