Did you know that you can hack into these systems simply by hitting the backspace key 28 straight times? What’s more, as Motherboard notes, several distributions including Debian, Red Hat and Ubuntu have all released emergency patches as well. The bug though silly is definitely a huge one and system administrators need to apply security updates for the distribution installed. Yes, it is THAT easy, if you want to bypass passwords on most Linux systems. After hitting the backspace key 28 times, users are directed to the grub rescue shell which lets them access the data of the computer, install malware, steal it or destroy it.
So how does Grub2 vulnerability actually work? In fact, trying to log in to someone else’s computer to compromise their files is practically impossible without the right set of tools. To check, start by clicking the backspace key 28 times in a row when met with the Grub username prompt during initial boot. “This results in an incalculable number of affected devices”, the researchers wrote in a blog post. “Even in the case that the disk is ciphered the attacker can overwrite it, causing a [denial of service]”, the report reads.
Two researchers in the Cybersecurity Group within the university were looking into ways you could cause a memory error from the password screen. If vulnerable, the machine will reboot or you will encounter a Grub rescue shell. Using this shell’s commands, an attacker can rewrite the Grub2 code loaded in RAM to completely bypass the authentication check.
When a computer is turned on, the bootloader loads first and then the operating system. The vulnerability has been spotted in Grub2, the Grand Unified Bootloader; the majority of Linux systems use Grub2 for booting the OS when starting the computer.