Bypass Linux Passwords by Pressing Backspace 28 Times

23 Dec 2015 | Author: | No comments yet »

Bypass Linux Passwords by Pressing Backspace 28 Times.

Pressing the backspace key 28 times can bypass the Grub2 bootloader’s password protection and allow a hacker to install malware on a locked-down Linux system.Researchers at the Polytechnic University of Valencia have figured out that many versions of Linux have a security flaw that allows users to bypass system security by pressing Backspace 28 times.Linux may be the operating system of choice for some computer snobs, but there is apparently one giant flaw in it: you can break into it really, really, really easily.

The source of the bug is an integer underflow fault that the researchers pin onto a single commit in 2009 – b391bdb2f2c5ccf29da66cecdbfb7566656a704d in case it was you – that affects the grub_password_get() function. The only method that could be manipulated by the user with common inputs was the Backspace method, which causes the system to revert to its “Grub rescue shell”. This protection is particularly important within organizations, where it is also common to disable CD-ROM, USB and network boot options and to set a password for the BIOS/UEFI firmware in order to secure computers from attackers who might gain physical access to the machines.

Without these boot options secured, attackers or malicious employees could simply boot from an alternative OS—like a live Linux installation stored on a USB drive or CD/DVD—and access files on a computer’s hard drive. Of course, it’s also possible for an attacker to remove the drive and place it in another machine that doesn’t have these restrictions, but there can be other physical access controls in place to prevent that. Depending on certain conditions, this can cause the machine to reboot or can put Grub in rescue mode, providing unauthenticated access to a powerful shell. Linux is tough to be a highly-secure operating system, not to say it is insecure, however, this is just another blunt reminder that no matter how secure a system may seem, they could be susceptible to minute yet critical flaws. If you are using a vulnerable operating system, it’s highly advised you install the emergency patches and double check to ensure your system is not vulnerable.

Linux is often thought of as a super secure operating system, but this is a good reminder to take physical security just as seriously as network security (if not more). The attacker can then return Grub to its normal operation mode and have full access to edit the boot entries because the authentication check is no longer performed.

Anything can be done to the computer once the hacker bypasses the password, so the developers strongly advise Linux users to install all updated made available to them, as fixes for the issue have already been developed. At this point multiple attack scenarios are possible, including destroying all data on the disk, but for their proof-of-concept exploit the researchers chose one that’s likely to be preferred by advanced attackers: installing malware that would steal legitimate users’ encrypted home folder data after they log in and unlock it.

Here you can write a commentary on the recording "Bypass Linux Passwords by Pressing Backspace 28 Times".

* Required fields
Twitter-news
Our partners
Follow us
Contact us
Our contacts

dima911@gmail.com

ICQ: 423360519

About this site