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Thread: Preboot authentication failure attemp Ubuntu drops to shell

  1. #1
    Join Date
    Mar 2013
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    75

    Preboot authentication failure attemp Ubuntu drops to shell

    Hello everyone,


    Just recently installed Ubuntu 13.04 (x64) on a new laptop (Acer s3). Basically, I bought this machine brand new, and installed Ubuntu over Windows 8 with the Live CD. I did not wipe the hard drive before the new install, I just mearly used Ubuntu's quick format method, and did not do any custom partitioning. I set up preboot authentication with LUKS (whole disk encryption) since it gave me the option to do so during installation. I also seperately encrypted the HOME directory.This morning, while half asleep, I had 3 consecutive preboot authentication failures attempts and I was dropped into a shell. Is this normal?

    I did read a little about initramfs. This does not appear to be a big gaping security hole? However, I am concerned about the alert. (/dev/mapper/ubuntu--vg-root does not exist.) Also want to mention that when I reboot the system, as long as I don't fail preboot authentication 3 times, it will let me boot right into the system. normally. Below is the message (retyped) displayed by Ubuntu.


    Gave up waiting or root device. Common Problems
    - Boot args (cat /prIoc/cmdline)
    - check rootdelay = '(did the system wait long enough?)
    -missing modules (cat /proc modules; is /dev)
    Alert! /dev/mapper/ubuntu--vg-root does not exist. Dropping to a shell


    BusyBox v1.20.2 (Ubuntu 1:1.20.0 - 8ubuntu1)
    built in shell (ash)
    enter 'help' for a list of built in commands
    (initramfs)_


    Any insight would be greatly appreciated.

    traxster

  2. #2
    Join Date
    Nov 2007
    Location
    Wisconsin
    Beans
    1,139

    Re: Preboot authentication failure attemp Ubuntu drops to shell

    The system drops to the busybox prompt only under a few circumstances. It means that the bootloader works, the kernel loads, and initramfs (the initial read-only) system loads. Then, the system unmounts the boot disk (which is read-only) and fails to remount it read-write.

    The most common reasons for dropping to busybox are:
    Grub misconfiguration (not your problem - it would drop to busybox every time)
    Hardware misconfiguration (UEFI, for example - see http://askubuntu.com/questions/29376...cpu-and-memory)
    Hardware failure - flaky HDD controller, or motherboard issue.

    Since it's intermittent on a new laptop, you might have a warranty hardware issue.


    Quote Originally Posted by Traxster View Post
    I did read a little about initramfs. This does not appear to be a big gaping security hole?
    In what way? Your data is encrypted. Go ahead, try to decrypt it.

  3. #3
    Join Date
    Mar 2013
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    75

    Re: Preboot authentication failure attemp Ubuntu drops to shell

    Quote Originally Posted by Cheesehead View Post
    In what way? Your data is encrypted. Go ahead, try to decrypt it.
    I encrypted the entire hard drive during the installation process. I think it is 256-AES-CBC

  4. #4
    Join Date
    Mar 2013
    Beans
    1

    Re: Preboot authentication failure attemp Ubuntu drops to shell

    Traxster, I suppouse Cheeseahead's question was rethorical
    You simply can't to decrypt your data without the key. If you lose it, you're in troubles
    LUKS is a great choice.

  5. #5
    Join Date
    Mar 2013
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    75

    Re: Preboot authentication failure attemp Ubuntu drops to shell

    Quote Originally Posted by Traxster View Post
    I encrypted the entire hard drive during the installation process. I think it is 256-AES-CBC

    I guess you were asking me in what way it is a security hole? is it possible for someone to get dumped to initramfs prompt, and say maybe load a program into it, that logs pw for luks? I can't imagine so, but check out this . scroll down to section 4.5. That is what got me worried.


    traxster

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