How to password-protect GRUB

Ubuntu 15.10 GRUB boot menu

Password-protecting the bootloader is one method you may employ to enhance the physical security profile of your computer. GRUB, the GRand Unified Bootloader, is the default bootloader on virtually all Linux distributions, but on a significant number, the installer does not have support for setting a GRUB password. This article presents the step involved in password-enabling GRUB – on a running system.

Before we go through the steps involved in setting a password for GRUB, it’s best to understand why this is even necessary. Principally, we password-enable GRUB to:

  1. Prevent Access To Single User Mode — If an attacker can boot into single user mode, he becomes the root user.
  2. Prevent Access To the GRUB Console — If the machine uses GRUB as its boot loader, an attacker can use the edit the command’s interface to change its configuration or to gather information using the cat command.
Related Post:  Customizing ALT Linux 5 Ark desktop

If your distribution’s installer has support for setting a GRUB password, the process involved should be similar to the one shown in the image below, which was taken from a similar Fedora 13 tutorial. Just check “Use a boot loader password” and the installer will prompt for a password.

GRUB password
Specifying boot loader password

If your distribution’s installer does not have support for setting a password for GRUB, you can still do it after installation. The process involved in this exercise is the same across distributions. However, for this article, an installation of Fedora 13 was used. Here are the steps involved:

  1. From a shell terminal, run the grub-md5-crypt command. The password that’s requested will be the one that’ll be used to protect GRUB. It should not be the same as that of any user account on the system, certainly not the same as the root password. Note the md5 hash generated. You will need it in the next step.
    GRUB hash
    Generate the md5 hash for password-protecting GRUB
  2. Edit /etc/grub.conf as shown in the image. Just add another line below the “timeout” line and type in password –md5 (md5 hash generated from step 1) as shown in the image. Save the file. Reboot and try to access other features of GRUB by pressing the “p” key. Did it work?
    GRUB.conf
    Edit grub.conf

Complete this simple process, and you would have taken a small but significant towards enhancing the physical security profile of your computer.

Related Post:  How to install Sabayon 5.3 on a btrfs filesystem

Share:

Share on facebook
Facebook
Share on twitter
Twitter
Share on pinterest
Pinterest
Share on linkedin
LinkedIn

Hola! Did you notice that LinuxBSDos.com no longer run network ads?  Yep, no more ads from the usual suspects that track and annoy you across the Internet. But since I still need to pay to keep the site running, feel free to make a small donation by PayPal or your favorite cryptocurrency.

  • Bitcoin
  • Ethereum
  • Xrp
  • Bitcoin cash
  • Bitcoin sv
  • Litecoin
  • Binance coin
  • Cardano
  • Ethereum classic
Scan to Donate Bitcoin to bc1qzvlte2m224zkayhdc7fdfjkp2rsgt0l5a496ua

Donate Bitcoin to this address

Scan the QR code or copy the address below into your wallet to send some Bitcoin

Scan to Donate Ethereum to 0x0F4362DFF77F3Ba0Dc637F5f3Eba35D09a2fA60C

Donate Ethereum to this address

Scan the QR code or copy the address below into your wallet to send some Ethereum

Scan to Donate Xrp to r4ggjvL36njsMCYTkJ3S7cTHscPsMsSGQv

Donate Xrp to this address

Scan the QR code or copy the address below into your wallet to send some Xrp

Scan to Donate Bitcoin cash to qrs0dedzp9t55af3nfwypydghp29r0xguy9s20fz2k

Donate Bitcoin cash to this address

Scan the QR code or copy the address below into your wallet to send some Bitcoin cash

Scan to Donate Bitcoin sv to 15K9TLyVDBtLuG9cYvXCX9SSkq9C9oUKHK

Donate Bitcoin sv to this address

Scan the QR code or copy the address below into your wallet to send some Bitcoin sv

Scan to Donate Litecoin to LetJ9QQMb7u2LMZ9Tu6rtHwcBcQFW98fbG

Donate Litecoin to this address

Scan the QR code or copy the address below into your wallet to send some Litecoin

Scan to Donate Binance coin to bnb1ga8trq08ssqepd90v6225nzfgy448pu5pw8gxp

Donate Binance coin to this address

Scan the QR code or copy the address below into your wallet to send some Binance coin

Scan to Donate Cardano to addr1qx2354yw49etstfljpdhwja3ajjlt487lg95vu9ngy2q6vu4rf2ga2tjhqknlyzmwa9mrm997h20a7stgectxsg5p5esq5l7d9

Donate Cardano to this address

Scan the QR code or copy the address below into your wallet to send some Cardano

Scan to Donate Ethereum classic to 0xcD6CC972a2297FcafACDcfE042C55C69516a9264

Donate Ethereum classic to this address

Scan the QR code or copy the address below into your wallet to send some Ethereum classic

Subscribe for updates. Trust me, no spam!

Sponsored links

1. Attend Algorithm Conference, a top AI and ML event.
2. Reasons to use control panel for your server.
3. DHgate Computers Electronics, Cell Phones & more.

Upcoming events

6 Responses

  1. Does this password-protect the computer from booting at all? Can we prevent individual GRUB entries from being booted without the PW, but let others boot without a PW? The practical and real-world uses are a bit light on details here…

    1. It does not. The reasons for password-enabling the GRUB (or any other bootloader’s) console are given at the top of the article. To prevent the computer from being booted by unauthorized persons, you will have to configure full disk encryption. Full disk encryption and password-enabling the GRUB console are just one of several methods you may use to enhance the physical security profile of your computer.

      “Can we prevent individual GRUB entries from being booted without the PW …?” In a dual-boot configuration, yes you can.

Leave a Reply

Your email address will not be published. Required fields are marked *

Get the latest

On social media
Via my newsletter

Partner links

1. Attend Algorithm Conference, a top AI and ML event for 2021.
2. Reasons to use control panel for your server.
3. DHgate Computers Electronics, Cell Phones & more.
Hacking, pentesting distributions

Linux Distributions for Hacking

Experts use these Linux distributions for hacking, digital forensics, and pentesting.

Categories
Archives

The authors of these books are confirmed to speak during

Algorithm Conference

T-minus AI

Author was the first chairperson of AI for the U.S. Air Force.

The case for killer robots

Author is the Director of the Center for Natural and Artificial Intelligence.

Why greatness cannot be planned

Author works on AI safety as a Senior Research Scientist at Uber AI Labs.