Linux-based systems have been found at risk due to a vulnerability in the Linux Unified Key Setup (LUKS), hard disk encryption standard that allows attackers to gain root-level access simply by holding down the Enter key for 70 seconds during boot time.
The vulnerability was first reported by Hector Marco Gisbert, a computer science lecturer at the University of the West of Scotland, and it seems to be affecting Linux distributions including Debian, Ubuntu, Fedora, Red Hat Enterpise Linux (RHEL), and SUSE Linux Enterprise Server (SLES).
The CVE-2016-4484 also states that the vulnerability can be remotely exploited in cloud environments, without physical access to the system. Because the fault is caused by incorrect handing of password checks, triggering the launch of a root shell, an attacker could access other unencrypted drives or perform various malicious actions.
“This vulnerability allows to obtain a root initramfs shell on affected systems,” reads the CVE. “The vulnerability is very reliable because it doesn’t depend on specific systems or configurations. Attackers can copy, modify or destroy the hard disc as well as set up the network to exflitrate data. This vulnerability is specially serious in environments like libraries, ATMs, airport machines, labs, etc, where the whole boot process is protect (password in BIOS and GRUB) and we only have a keyboard or/and a mouse.”
Fixing the issue involves stopping the boot sequence after exhausting a number of password guesses and suspending the execution forever. The patch should become available soon, but Linux users can manually patch the configuration file by “adding the “panic” parameter to the kernel entry in the grub configuration”.
The CVE also details some exploitation strategies that revolve around privilege escalation, information disclosure and denial of service by deleting all information stored on all disks. Also, the disclosure covers the issues that could arise from having physical access to compromised devices, but also what would happen if IoT devices running these vulnerable Linux distributions were to be compromised.