How easy is break a password in Linux?

Discussion
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Hello Friends

According with your own experience (or by 3rd party as co-workers, family, etc)

Question

  • How easy is break a password in Linux?

At first glance define a password being either short or common (or known as superman, god, matrix, neo) is a catastrophic approach, but even if the password has 10 to 15 characters … how easy is?

Suppose you must run an app in Linux in a LAN, and assume some bad element arrives to the server for any reason, turns on the monitor (if any) and wants get access for the main/primary user (the one with sudo, it for example for Fedora, Ubuntu)

Thanks for your understanding

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Using only N.I. :slight_smile:
Ok, the second part may be questionable, but the first list generated by AI seems to me really exhaustive.

When it comes to the second part:

Also ensure the CMOS battery soldered, unremoveable, unshortcicuitable, etc…
Otherwise BIOS password is reset via powering the CMOS down :slight_smile:

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There has been a breach of our AI etiquette in this topic, and the perpetrator has been politely warned.
Any further breaches will result in deletions.
It is a fine line … be careful please.
Remember Abhishek’s words… the forum is for interaction between humans. There must be some human content in a post.

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Hello Neville

Thanks a lot for handled this situation

About AI I had the experience about Java AspectJ many times where I got errors about the AI results. Now, because a OS is more crucial for configurations and is critical avoid crash the OS itself: Therefore I create here any post because I prefer always a human experience.

And Yes: I use few AI only for Programming (and only as a reference), not for configuration of the OS itself.

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First time I read something about this, how the bold part would be a concern of security in Linux?

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Not exactly in Linux, but on the way to it.
Say you want your machine secure, and disable booting from any device except the builtin drive.
Your OS and it’s data is inaccessible without firs logging in to your installed system.
But what if a bad boy comes, and wants to boot from a live USB, so circumvent your login procedure? Just enter BIOS, change boot settings, enable booting from USB, and boot from USB, access your data, etc.
Obviously he can’t do that, if the BIOS has a password.
But the way is still open to reset the password via remove or short circuit of the battery.
After 7..8 minutes the BIOS will “forget” everything, including the password.

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Hello László

Huge Thanks for the reply

Not exactly in Linux, but on the way to it.
Say you want your machine secure, and disable booting from any device except the builtin drive.

Good point for the second line

Your OS and it’s data is inaccessible without firs logging in to your installed system.

Agree, it is the reason of the creation of this post, if the password is broken is a big problem

But what if a bad boy comes, and wants to boot from a live USB, so circumvent your login procedure?

Good point, has a lot of sense, it was the possible solution for my Asus when my BIOS always was loaded and the SSD did not boot. Correct the Live boot is able to mount the SSD and all is stolen

Just enter BIOS, change boot settings, enable booting from USB, and boot from USB, access your data, etc.

Of course, has sense that approach

Obviously he can’t do that, if the BIOS has a password

Agree

But the way is still open to reset the password via remove or short circuit of the battery.
After 7..8 minutes the BIOS will “forget” everything, including the password.

Oh ok … interesting that scenario

Again huge thanks for the information

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You are welcome :wink:
After all, if the attacker has physical access, the battle is probably lost.
Actually there would be another solution, and that is to use drive encryption, which I do not prefer.
I find it risky, and possible to lock out myself when something goes wrong in boot process.
But I’m not completely sure about this one.

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Thanks for the reply László

After all, if the attacker has physical access, the battle is probably lost.

Yes, agree, with the battery case all is lost

Actually there would be another solution, and that is to use drive encryption,

Sounds interesting. I remember some months ago I thought about that but due tight time I put that option in stand by

which I do not prefer.

Why?

I find it risky, and possible to lock out myself when something goes wrong in boot process.

Now I see your point. How probable is that horrible situation?

But I’m not completely sure about this one.

Do you mean about the post’s title?

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I don’t encrypt the root partition, but I use Lux to encrypt my data partition that I want to protect.
So even if someone crack my root password, there is another level of protection.

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Hello Howard

Huge Thanks for that important information!

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I meant about locking myself out. So it may be possible to recover having the encryption keys stored somewhere, but I never really tried. I feel safe and comfortable with my unencrypted partitions, as I don’t need to worry about bad guys breaching to reach my data. I have nothing that would be like an NSA secret :slight_smile:

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If you forget or lose the root password, you can use grub to get a root shell and set a new root password …

  • boot to the grub menu
  • type ‘e’ to enter edit mode
  • go to the linux line and add init=/bin/bash rw
  • boot with F10 and you will get a root shell
  • use passwd to set a new root password
  • reboot and login with the new root password

That is why they wanted secure boot. Grub use is not passworded.

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Not if you disable recovery option in GRUB.
Put (or uncomment) GRUB_DISABLE_RECOVERY="true" in /etc/default/grub and do update-grub.

I’d just boot with any live distro, then as root chrootinto the installed system, and issue
passwd

Root password will be reset.

With encrypted drives (partitions) this won’t work,
I’m concerned about losing data on encrypted drives via loosing keys for whatever reason.

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Would you need to mount something?

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Sure, the same like when reinstalling GRUB.

mount /dev/sdXY /mnt #/dev/sdXY is the root partition of the installed system
mount --bind /dev /mnt/dev
mount --bind /dev/pts /mnt/dev/pts
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
chroot /mnt

After chroot, we have a root shell bind to the installed system.

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I copy this back in 2023,

Update
Tried it twice and this method does not work.
I am going to remove the procedure.

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That is the same as @kovacslt suggested… except he wanted some more mounts.
It looks OK to me … try it

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Do you have the encrypted partition auto mounted at boot? So you need to give your user password and encryption password at boot? Or do you manually mount the data partition when you need to access it?

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Yes, this is the way I mount the LUX partition or external LUX disk.

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